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Relay Technical Information

Definition of Relay Terminology

Relay Technical Information
Definition of Relay Terminology
(also referred to as primary or input) · Nominal Coil Voltage (Rated Coil Voltage) A single value (or narrow range) of source voltage intended by design to be applied to the coil or input. · Pick-Up Voltage (Pull-In Voltage or Must Operate Voltage) As the voltage on an unoperated relay is increased, the value at or below which all contacts must function (transfer). · Drop-Out Voltage (Release or Must Release Voltage) As the voltage on an operated relay is decreased, the value at or above which all contacts must revert to their unoperated position. · Maximum Continuous Voltage The maximum voltage that can be applied continuously to the coil without causing damage. Short duration spikes · Coil Designation
Single side stable type Non-polarized Polarized 1 coil latching type
2 coil latching type 4-terminal 3-terminal
A black coil represents the energized state. For latching relays, schematic diagrams generally show the coil in its reset state. Therefore, the coil symbol is also shown for the reset coil in its reset state.
CONTACTS (secondary or output)
· Contact Forms Denotes the contact mechanism and number of contacts in the contact circuit. · Contact Symbols
Form A contacts (normally open contacts)
· Maximum Switching Voltage The maximum open circuit voltage which can safely be switched by the contacts. AC and DC voltage maximums will differ in most cases. · Maximum Switching Current The maximum current which can safely be switched by the contacts. AC and DC current maximums may differ. · Maximum Switching Power The upper limit of power which can be switched by the contacts. Care should be taken not to exceed this value. · Maximum Carrying Current The maximum current which after closing or prior to opening, the contacts can safely pass without being subject to temperature rise in excess of their design limit, or the design limit of other temperature sensitive components in the relay (coil, springs, insulation, etc.). This value is usually in excess of the maximum switching current. · Maximum Switching Capability The minimum value of voltage and current which can be reliably switched by the contacts. These numbers will vary from device type to device type. Factors affecting minimums include contact material, contact pressure, wipe, ambient conditions and type of relay enclosure (sealed vs. non-sealed). · Maximum Switching Capacity This is listed in the data column for each type of relay as the maximum value of the contact capacity and is an interrelationship of the maximum switching power, maximum switching voltage, and maximum switching current. The switching current and switching voltage can be obtained from this graph. For example, if the switching voltage is fixed in a certain application, the maximum switching current can be obtained from the intersection between the voltage on the axis and the maximum switching power. Maximum Switching Capacity (DS relay) Example: Using DS relay at a switching voltage of 60V DC, the maximum switching current is 1A. Maximum switching capacity is given for a resistive load. Be sure to carefully check the actual load before use.
Form B contacts (normally closed contacts)
Form C contacts (changeover contacts)
Definition of Relay Terminology
1, 000V
Maximum switching capacity
10mV 10µA
100mA
1A DC current
· Breakdown Voltage (Hi-Pot or Dielectric Strength) The maximum voltage which can be tolerated by the relay without damage for a specified period of time, usually measured at the same points as insulation resistance. Usually the stated value is in VAC (RMS) for one minute duration. · Surge Withstand Voltage The ability of the device to withstand an abnormal externally produced power surge, as in a lightning strike, or other phenomenon. An impulse test waveform is usually specified, indicating rise time, peak value and fall time. (Fig. 2)
· Contact Resistance This value is the combined resistance of the resistance when the contacts are touching each other and the resistance of the terminals and contact spring. The contact resistance is measured using the voltage-drop method as shown below. The measuring currents are designated in Fig. 1.
Wave peak value
1.2 Time(µs)
Measured contact
FIG. 2
Power source (AC or DC)
A : Ammeter V :
Voltmeter R : Variable resister
FIG. 1
Test Currents
Rated Contact Current or Test Current Switching Current (A) (mA) Less than 0.01 1 0.01 or more and less than 0.1 10 0.1 or more and less than 1 100 1 or more 1, 000
The resistance can be measured with reasonable accuracy on a YHP 4328A milliohmmeter. In general, for relays with a contact rating of 1A or more, measure using the voltage-drop method at 1A 6V DC. · Capacitance This value is measured between the terminals at 1kHz and 20°C 68°F.
PERFORMANCE
· Insulation Resistance The resistance value between all mutually isolated conducting sections of the relay, i.e. between coil and contacts, across open contacts and between coil or contacts to any core or frame at ground potential. This value is usually expressed as "initial insulation resistance" and may decrease with time, due to material degradation and the accumulation of contaminants.
· Operate Time (Pull-In or Pick-Up Time) The elapsed time from the initial application of power to the coil, until the closure of the normally open contacts. (With multiple pole devices the time until the last contact closes.) This time does not include any bounce time. · Operate Bounce Time The time period immediately following operate time during which the contacts are still dynamic, and ending once all bounce has ceased. · Release Time (Drop-Out Time) The elapsed time from the initial removal of coil power until the reclosure of the normally closed contacts (last contact with multi-pole) this time does not include bounce. · Release Bounce Time The time period immediately following release time during which the contacts are still dynamic, ending when all bounce has ceased. · Set Time Term used to describe operate time of a bi-stable or latching relay. · Reset Time Term used to describe release time of a bi-stable or latching relay. With a w-coil magnetic latching relay the time is from the first application of power to the reset coil until the reclosure of the reset contacts. With a single coil latching relay, the time is measured from the first applica-
DC voltage
Definition of Relay Terminology
Life Curve
HIGH FREQUENCY CHARACTERISTICS
30V DC resistance load
125V AC resistance load 10
1 Current (A)
· Isolation High frequency signals leak through the stray capacitance across contacts even if the contacts are separated. This leak is called isolation . The symbol dB (decibel) is used to express the magnitude of the leak signal. This is expressed as the logarithm of the magnitude ratio of the signal generated by the leak with respect to the input signal. The larger the magnitude, the better the isolation. · Insertion Loss At the high frequency region, signal disturbance occurs from self-induction, resistance, and dielectric loss as well as from reflection due to impedance mismatching in circuits. Loss due to any of these types of disturbances is called insertion loss. Therefore, this refers to the magnitude of loss of the input signal. the relay from large particulate contamination, and also may protect user personnel from a shock hazard. · Flux-Resistant Type In this type of construction, solder flux penetration is curtailed by either insert molding the terminals with the header, or by a simple sealing operation during manufacturing. · Sealed Type This type of sealed relay totally excludes the ingress of contaminants by way of a sealing compound being applied to the header / cover interface. The constituent components are annealed for physical and chemical stability. This annealing
PROTECTIVE CONSTRUCTION
Several different degrees of protection are provided for different relay types, for resistance to dust, flux, contaminating environments, automatic cleaning, etc. · Open Type For reasons of cost, some devices are not provided with any enclosure. It is usually assumed that the end application will be in an overall enclosure or protective environment. · Dust Cover Type Most standard relays are provided with a dust cover of some type. This protects
CONSTRUCTION AND CHARACTERISTIC
Type Construction
Characteristics Automatic Soldering Dust Cover Type Most basic construction where the case and base (or body) are fitted together. Terminals are sealed or molded simultaneously. The joint between the case and base is higher than the surface of the PC board. Terminals, case, and base are filled with sealing resin.
Automatic Cleaning
Harmful Gas Resistance
Flux-Resistant Type
Sealed Type
Sealing resin
Metal case
Metallic Hermetic Seal Type
Hermetically sealed with metal case and metal base. Terminals are sealed with glass.
Glass
Metal base
Cleaning solvent Although absorption by plastic does occur, it is insignificant in actual practice. Use the metallic hermetic seal type for explosion-proof requirements.
Definition of Relay Terminology
OPERATIONAL FUNCTION
· Single Side Stable Type Relay which turns on when the coil is energized and turns off when deenergized. (Fig. 3)
· 2 Coil Latching Type Relay with a latching construction composed of 2 coils: set coil and reset coil. The relay is set or reset by alternately applying pulse signals of the same polarity. (Fig. 5)
Fig. 5 Fig. 3
(Typical schematic for DS relay)
· 1 Coil Latching Type Relay with a latching construction that can maintain the on or off state with a pulse input. With one coil, the relay is set or reset by applying signals of opposite polarities. (Fig. 4)
· Operation Indication Indicates the set and reset states either electrically or mechanically for easy maintenance. An LED wired type (LED wired HC relay), lamp type (lamp wired HP relay) are available. (Fig. 6)
- LED wired HC relay
Fig. 6
Fig. 4
(Typical schematic for DS relay)
TERMINAL CONFIGURATION
Type PC board through hole terminal PC board clinching terminal PC board surface-mount terminal Plug-in terminal Quick connect terminal Screw terminal
Typical relay type
Terminal configuration
TQ, TF, TN, TK, TX, TX-D TX-S relay, DS relay, DS-BT relay, RP relay, RM relay, JS relay, JW relay, S relay, JQ relay, PQ relay
Typical relay type
TQ, TF, TN, TK, TX-SMD, TQ-SMD, TX, TX-D, TX-S relay relay, SMD type
K relay HC relay HP relay HE relay
JC relay JR relay JA relay
JH relay VC relay HE relay
MOUNTING METHOD
Type Insertion mount
Mounting configuration
Typical relay type
Notes: 1. Sockets are available for certain PC board relays. (NR relay, S relay, ST relay, etc.) 2. M type (solder type) for direct screw mounting of case is also available. (K relay, HG relay) 9-4
Surface mount Socket mount Terminal socket mount type TMP type
Terminal Socket
TQ, TF, TN, TK, TX, TX-D, TX-S relay, DS relay, DS-BT relay, RP relay, RM relay, S relay
TX-SMD, TQ-SMD, relay, SMD type
K relay NC relay HC relay
HC relay HP relay HG relay
HC relay JR relay JC relay
JR relay JC relay JM relay JT-N relay
General Application Guidelines
A relay may encounter a variety of ambient conditions during actual use resulting in unexpected failure. Therefore, testing over a practical range under actual operating conditions is necessary. Application considerations should be reviewed and determined for proper use of the relay.
METHOD OF DETERMINING SPECIFICATIONS
In order to use the relays properly, the characteristics of the selected relay should be well known, and the conditions
Specification item a) Rating b) Pick-up voltage (current) c) Drop-out voltage (current) d) Maximum continuous impressed voltage (current) e) Coil resistance f ) Impedance g) Temperature rise h) Input frequency for AC type a) Contact arrangement b) Contact rating c) Contact material d) Life e) Contact pressure f ) Contact resistance a) Operate time b) Release time c) Bounce time d) Switching frequency a) Vibration resistance b) Shock resistance c) Ambient temperature d) Life a) Mounting method b) Cover c) Size
of use of the relay should be investigated to determine whether they are matched to the environmental conditions, and at the same time, the coil conditions, contact conditions, and the ambient conditions for the relay that is actually used must be sufficiently known in advance.
In the table below, a summary has been made of the points of consideration for relay selection. It may be used as a reference for investigation of items and points of caution.
Consideration points regarding selection
1) Select relay with consideration for power source ripple. 2) Give sufficient consideration to ambient temperature and for the coil temperature rise. 3) When used in conjunction with semiconductors, additional attention to the application should be taken.
Contacts
Operate time
1) It is beneficial to have the bounce time short for sound circuits and similar applications.
Mechanical characteristics
Other items
BASICS ON RELAY HANDLING
General Application Guidelines
PROBLEM POINTS WITH REGARD TO USE
In the actual use of relays, various ambient conditions are encountered, and because unforeseen events occur which can not be thought of on the drawing board, with regard to such conditions, tests are necessary under the possible range of operation. For example, consideration must always be given to variation of performance when relay characteristics are being reviewed. The relay is a mass production item, and as a matter of principle, it must be recognized that the relay is to be used to the extent of such variations without the need for adjustment.
RELAY COIL
· AC operation type For the operation of AC relays, the power source is almost always a commercial frequency (50 or 60Hz) with standard voltages of 6, 12, 24, 48, 115, and 240V AC. Because of this, when the voltage is other than the standard voltage, the product is a special order item, and the factors of price, delivery, and stability of characteristics may create conveniences. To the extent that it is possible, the standard voltages should be selected. Also, in the AC type, shading coil resistance loss, magnetic circuit eddy current loss, and hysteresis loss exit, and because of lower coil efficiency, it is normal for the temperature rise to be greater than that for the DC type. Furthermore, because humming occurs below the level of pick-up voltage (minimum operating voltage), care is required with regard to power source voltage fluctuations. For example, in the case of motor starting, if the power source voltage drops, and during the humming of the relay, if it reverts to the restored condition, the contacts suffer a burn damage and welding, with the occurrence of a false operation self-maintaining condition. For the AC type, there is an inrush current during the operation time (for the separated condition of the armature, the impedance is low and a current greater than rated current flows for the adhered condition of the armature, the impedance is high and the rated value of current flows), and because of this, for the case of several relays being used in parallel connection, it is necessary to give consideration to power consumption. · DC operation type For the operation of DC relays, standards exist for power source voltage and current, with DC voltage standards set at 5, 6, 12, 24, 48, and 100V, but with regard to current, the values as expressed in catalogs in milliamperes of pick-up current. However, because this value of pick-up current is nothing more than a guarantee of just barely moving the armature, the variation in impressed voltage and resistance values, and the increase in coil resistance due to temperature rise, must be given consideration for the worst possible condition of relay operation, making it
Fig. 1 Distortion in an AC stabilized power source
circuit is connected to the same line as motors, solenoids, transformers, and other loads, when these loads operate, the line voltage drops, and because of this the relay contacts suffer the effect of vibration and subsequent burn damage. In particular, if a small type transformer is used and its capacity has no margin of safety, when there is long wiring, or in the case of household used or small sales shop use where the wiring is slender, it is necessary to take precautions because of the normal voltage fluctuations combined with these other factors. When trouble develops, a survey of the voltage situation should be made using a synchroscope or similar means, and the necessary counter-measures should be taken, and together with this determine whether a special relay with suitable excitation characteristics should be used, or make a change in the DC circuit as shown in Fig. 2 in which a capacitor is inserted to absorb the voltage fluctuations. In particular, when a magnetic switch is being used, because the load becomes like that of a motor, depending upon the application, separation of the operating circuit and power circuit should be tried and investigated.
Sine wave
Approximate keystone wave
Waveform with a this harmonic included
Fig. 2 Voltage fluctuation absorbing circuit using a condenser
T Switch 100V AC 24V DC C R Relay coil
General Application Guidelines
Current passage time
R Relay Smoothing capacitor Ripple portion
Emax. Emin.
Emean.
DC portion
Fig. 3
addition of a smoothing capacitor, it can be used. However, the ripple and the characteristics must be investigated. 3 For the hinge type relay, there are types which cannot use the full wave rectifier alone and other types which can use the full wave rectifier alone, and it is necessary to discuss this with the maker to determine which is possible.
have erroneous operation or abnormal operation. To understand this condition while preparing sequence circuits, as shown in Fig. 5, with 2 lines written as the power source lines, the upper line is always k and the lower line k (when the + - circuit is AC, the same thinking applies). Accordingly the k side is necessarily the + side for making contact connections (contacts for relays, timers, limit switches, etc.), and the k side is the load cir- cuit side (relay coil, timer coil, magnet coil, solenoid coil, motor, lamp, etc.). Fig. 6 shows an example of stray circuits. In Fig. 6 (a), with contacts A, B, and C closed, after relays R1, R2, and R3 operate, if contacts B and C open, there is a series circuit through A, R1, R2, and R3, and the relays will hum and sometimes not be restored to the drop out condition. The connections shown in Fig. 6 (b) are correctly made. In addition, with regard to the DC circuit, because it is simple by means of a diode to prevent stray circuits, proper application should be made.
Voltage
Upper side line Contact circuit Power source lines R Load circuit Lower side line
Fig. 4
Fig. 5 Example of a vertically written sequence circuit
General Application Guidelines
(a) Not a good example
(b) Correct example
Fig. 6 Stray circuits
· Gradual increase of coil impressed voltage and suicide circuit When the voltage impressed on the coil is increased slowly, the relay transferring operation is unstable, the contact pressure drops, contact bounce increases, and an unstable condition of contact occurs. This method of applying voltage to the coil should not be used, and consideration should be given to the method of impressing voltage on the coil (use of switching circuit). Also, in the case of latching relays, using self contacts "B, " the method of self coil circuit for complete interruption is used, but because of the possibility of trouble developing, care
should be taken. The circuit shown in Fig. 7 causes a timing and sequential operation using a reed type relay, but this is not a good example with mixture of gradual increase of impressed voltage for the coil and a sucide circuit. In the timing portion for relay R1, when the timing times out, chattering occurs causing trouble. In the initial test (trial production), it shows favorable operation, but as the number of operations increases, contact blackening (carbonization) plus the chattering of the relay creates instability in performance.
Instability point Switch R1 a R1 b X E C R1 C R2 R2 a R2 b X SW ON
R1: Reed relay R2: Reed relay
C: Capacitor X: Variable resistance (for time adjustment)
R1a: Form A of relay R1 R1b: Form B of relay R1
Fig. 7 A timing and sequential operation using a reed type relay
· Phase synchronization in AC load switching If switching of the relay contacts is synchronized with the phase of the AC power, reduced electrical life, welded contacts, or a locking phenomenon
(incomplete release) due to contact material transfer may occur. Therefore, check the relay while it is operating in the actual system. However, if problems develop, control the relay using an appropriate phase. (Fig. 8)
Ry Vin.
Load voltage Vin.
Fig. 8
· Erroneous operation due to inductive interference In situations where both control and load wiring are in close proximity, thought should be given to separating or shielding the conductors in order to prevent false relay operation. This becomes increasingly important with long wiring runs, and can be achieved by using separate conduit for load and control conductors. Inductive coupling can also be minimized by maintaining a large physical separation of the load and control wiring. · Influence of external magnetic fields Many modern electro-mechanical relays are of polarized, high sensitivity design. Care should be exercised in the placement of these devices when strong, external magnetic fields are present, such as in proximity to power transformers or permanent magnets (speakers, etc.). Operational characteristics may change under an external magnetic influence. · Long term current carrying In applications which involve lengthy duty cycles, the preferred configuration would be the use of the form B or N.C. contacts for long term duty. In those instances where the form A contact is held closed for extensive time periods, coil heating will increase contact "T" rise and may result in shorter than optimum life. Alternately, latching types may be considered for these applications, using a storage capacitor to "Reset" the relay on powerdown. · Regarding electrolytic corrosion of coils In the case of comparatively high voltage coil circuits (in particular above 48 V DC), when such relays are used in high temperature and high humidity atmospheres or with continuous passage of current, the corrosion can be said to be the result of the occurrence of electrolytic corrosion. Because of the possibility of open circuits occurring, attention should be given to the following points. 1 The k side of the power source + should be connected to the chassis. (Refer to Fig. 9) (Common to all relays) 2 In the case where unavoidably the k - side is grounded, or in the case where grounding is not possible. (1) Insert the contacts (or switch) in the + k side of the power source, and connect the start of the coil winding the k side. - (Refer to Fig. 10) (Common to all relays) (2) When a grounding is not required, connect the ground terminal to the k + side of the coil. (Refer to Fig. 11) (NF and NR with ground terminal) 3 When the k side of the power source - is grounded, always avoid interting
General Application Guidelines
the contacts (and switches) in the k side. - (Refer to Fig. 12) (Common to all relays) 4 In the case of relays provided with a ground terminal, when the ground terminal is not considered effective, not making a connection to ground plays an
Judgment: Good (Fig. 9)
important role as a method for preventing electrolytic corrosion. Note: The designation on the drawing indicates the insertion of insulation between the iron core and the chassis. In relays where a ground terminal is providJudgment: Good (Fig. 11)
Switch Bobbin Switch
ed, the iron core can be grounded directly to the chassis, but in consideration of electrolytic corrosion, it is more expedient not to make the connection.
Judgment: Good (Fig. 10)
Judgment: No good (Fig. 12)
Bobbin
Relay coil
Iron core
Relay coil
Iron core
Relay coil
Iron core
Switch
R (Insulation resistance)
Start of coil winding
R (Insulation resistance)
Bobbin
Switch
CONTACT
The contacts are the most important elements of relay construction. Contact performance conspicuously influenced by contact material, and voltage and current values applied to the contacts (in particular, the voltage and current 1. Contact circuit voltage, current, and load Voltage, AC and DC When there is inductance included in the circuit, a rather high counter emf is generated as a contact circuit voltage, and since, to the extent of the value of that voltage, the energy applied to the contacts causes damage with consequent wear of the contacts, and transfer of the contacts, it is necessary to exercise care with regard to control capacity. In the case of DC, there is no zero current point such as there is with AC, and accordingly, once a cathode arc has been generated, because it is difficult to quench that arc, the extended time of the arc is a major cause. In addition, due to the
waveforms at the time of application and release), the type of load, frequency of switching, ambient atmosphere, form of contact, contact switching speed, and of bounce. Because of contact transfer, welding,
abnormal wear, increase in contact resistance, and the various other damages which bring about unsuitable operation, the following items require full investigation.
direction of the current being fixed, the phenomenon of contact shift, as noted separately below, occurs in relation to the contact wear. Ordinarily, the approximate control capacity is mentioned in catalogues or similar data sheets, but this alone is not sufficient. With special contact circuits, for the individual case, the maker either estimates from the past experience or makes test on each occasion. Also, in catalogues and similar data sheets, the control capacity that is mentioned is limited to resistive load, but there is a broad meaning indicated for that class of relay, and ordinarily it is
proper to think of current capacity as that for 125V AC circuits. Current The current at both the closing and opening time of the contact circuit exerts important influence. For example, when the load is either a motor or a lamp, to the extent of the inrush current at the time of closing the circuit, wear of the contacts, and the amount of contact transfer increase, and contact welding and contact transfer make contact separation impossible.
Relay coil
End of coil winding
Iron core
R (Insulation resistance)
General Application Guidelines
2. Characteristics of Common Contact Materials Characteristics of contact materials are given below. Refer to the when selecting a relay.
Contact Material
Surface Finish
at the instant the inductive load is switched off. The counter emf passes through the power supply line and reaches both contacts. Generally, the critical dielectric breakdown voltage at standard temperature and pressure in air is about 200 to 300 volts. Therefore, if the counter emf exceeds this, discharge occurs at the contacts to dissipate the energy (1 / 2Li2) stored in the coil. For this reason, it is desirable to absorb the counter emf so that it is 200V or less. A memory oscilloscope, digital memory, peak hold meter, etc., can be used to measure the counter emf. However, since the waveform is extremely steep, considerable discrepancies may result depending on the precision of the equipment used. The table shows the counter emf of various relays measured on a high precision peak hold meter. Actual measurement of counter emf on a peak hold meter
Nominal Coil Voltage Relay Type NR relay (single side stable) NF4 relay 6V DC 144V 410V 12V DC 165V 470V 24V DC
develop such as those shown in Fig. 14. After a while, the uneven contacts lock as if they were welded together. This often occurs in circuits where sparks are produced at the moment the contacts "make" such as when the DC current is large for DC inductive or capacitive loads or when the inrush current is large (several amperes or several tens of amperes). Contact protection circuits and contact materials resistant to material transfer such as AgW or AgCu are used as countermeasures. Generally, a concave formation appears on the cathode and a convex formation appears on the anode. For DC capacitive loads (several amperes to several tens of amperes), it is always necessary to conduct actual confirmation tests.
Meterial transfer of contacts 188V 510V
Fig. 14
Fig. 13 Example of counter emf and actual measurement on a peak hold meter.
· Material Transfer Phenomenon Material transfer of contacts occurs when one contact melts or boils and the contact material transfers to the other contact. As the number of switching operations increases, uneven contact surfaces
General Application Guidelines
· Contact Protection Circuit Use of contact protective devices or protection circuits can suppress the counter
Circuit
Contact Inductive load
emf to a low level. However, note that incorrect use will result in an adverse
Application AC DC
effect. Typical contact protection circuits are given in the table below.
Circuit
If the load is a timer, leakage current flows through the CR circuit causing faulty operation.
Circuit
If used with AC voltage, be sure the impedance of the load is sufficiently smaller than that of the CR circuit
CR circuit
Contact r c Inductive load
If the load is a relay or solenoid, the release time lengthens. Effective when connected to both contacts if the power supply voltage is 24 or 48V and the voltage across the load is 100 to 200V.
As a guide in selecting r and c, r: 0.5 to 1 per 1V contact voltage c: 0.5 to 1µF per 1A contact current Values vary depending on the properties of the load and variations in relay characteristics. Capacitor c acts to suppress the discharge the moment the contacts open. Resistor r acts to limit the current when the power is turned on the next time. Test to confirm. Use a capacitor with a breakdown voltage of 200 to 300V. Use AC type capacitors (non-polarized) for AC circuits.
Contact Inductive load
Diode circuit
Diode
The diode connected in parallel causes the energy stored in the coil to flow to the coil in the form of current and dissipates it as joule heat at the resistance component of the inductive load. This circuit further delays the release time compared to the CR circuit. (2 to 5 times the release time listed in the catalog)
Use a diode with a reverse breakdown voltage at least 10 times the circuit voltage and a forward current at least as large as the load current. In electronic circuits where the circuit voltages are not so high, a diode can be used with a reverse breakdown voltage of about 2 to 3 times the power supply voltage.
Contact
Diode and zener diode circuit
Inductive load
Effective when the release time in the diode circuit is too long.
Use a zener diode with a zener voltage about the same as the power supply voltage.
Contact Inductive load
Varistor circuit
Varistor
Using the stable voltage characteristics of the varistor, this circuit prevents excessively high voltages from being applied across the contacts. This circuit also slightly delays the release time. Effective when connected to both contacts if the power supply voltage is 24 or 48V and the voltage across the load is 100 to 200V.
· Avoid using the protection circuits shown in the figures on the right. Although DC inductive loads are usually more difficult to switch than resistive loads, use of the proper protection circuit will raise the characteristics to that for resistive loads. (Fig. 15)
Fig. 15
Contact
No good
Although extremely effective in arc suppression as the contacts open, the contacts are susceptible to welding since energy is stored in C when the contacts open and discharge current flows from C when the contacts close.
Although extremely effective in arc suppression as the contacts open, the contacts are susceptible to welding since charging current flows to C when the contacts close.
· Mounting the Protective Device In the actual circuit, it is necessary to locate the protective device (diode, resistor, capacitor, varistor, etc.) in the immediate vicinity of the load or contact. If located too far away, the effectiveness of the protective device may diminish. As a guide, the distance should be within 50cm. · Abnormal Corrosion During High Frequency Switching of DC Loads (spark generation) If, for example, a DC valve or clutch is switched at a high frequency, a bluegreen corrosion may develop. This occurs from the reaction with nitrogen in the air when sparks (arc discharge) are generated during switching. For relays
with a case, the case must be removed or air holes drilled in the case. A similar phenomenon occurs in the presence of ammonia-based gas. Therefore, care is required in circuits where sparks are generated at a high frequency. · Type of Load and Inrush Current The type of load and its inrush current characteristics, together with the switching frequency are important factors which cause contact welding. Particularly for loads with inrush currents, measure the steady state current and inrush current and select a relay which provides an ample margin of safety. The table on the right shows the relationship between typical loads and their inrush currents.
Type of load Resistive load Solenoid load Motor load Incandescent lamp load Mercury lamp load Sodium vapor lamp load Capacitive load Transformer load
Inrush current Steady state current 10 to 20 times the steady state current 5 to 10 times the steady state current 10 to 15 times the steady state current Approx. 3 times the steady state current 1 to 3 times the steady state current 20 to 40 times the steady state current 5 to 15 times the steady state current
Power C supply
Power supply
General Application Guidelines
Load Inrush Current Wave and Time
Contacts L
io (for high power factor type) 3 to 5 minutes The discharge tube, transformer, choke coil, capacitor, etc., are combined in common discharge lamp circuits. Note that the inrush current may be 20 to 40 times, especially if the power supply impedance is low in the high power factor type. 10 seconds or less
Incandescent lamp
i 0.07 to 0.1 second 0.2 to 0.5 second Conditions become harsher if plugging or inching is performed since state transitions are repeated. 1 to 2 cycles (1 / 60 to 1 / 30 seconds)
1 / 2 to 2 cycles (1 / 120 to 1 / 30 seconds)
· When Using Long Wires If long wires (100 to 300m) are to be used in a relay contact circuit, inrush current may become a problem due to the stray capacitance existing between wires. Add a resistor (approx. 10 to 50) in series with the contacts. (Fig. 16)
Equivalent circuit
Contacts Added resistor Wire 10 to 50 (100 to 300m) Stray capacitance of wire
Fig. 16
· Phase Synchronization in Switching AC Loads If switching of the relay contacts is synchronized with the phase of the AC power, reduced electrical life, welded contacts, or a locking phenomenon (incomplete release) due to contact material transfer may occur. Therefore, check the relay while it is operating in the actual system. However, if problems develop, control the relay using an appropriate phase. (Fig. 17) 4. Cautions on Use Related to Contacts · Connection of load and contacts Connect the load to one side of the power supply as shown in Fig. 18 (a). Connect the contacts to the other side. This prevents high voltages from developing between contacts. If contacts are connected to both side of the power supply as shown in (b), there is a risk of shorting the power supply when relatively close contacts short.
Ry Vin
Load voltage Load voltage Vin
Fig. 17
Fig. 18
(a) Good example
(b) Bad example
General Application Guidelines
· Dummy Resistor Since voltage levels at the contacts used in low current circuits (dry circuits) are low, poor conduction is often the result. One method to increase reliability is to add a dummy resistor in parallel with the load to intentionally raise the load current reaching the contacts. Care is required especially for low-level switching circuits (0.1V or less, 0.2mA or less). Contact material and, of course, use of bifurcated contacts must also be taken into consideration.
· Avoid Circuits Where Shorts Occur Between Form A and B Contacts (Fig. 19) 1) The clearance between form A and B contacts in compact control components is small. The occurrence of shorts due to R1 arcing must be assumed. 2) Even if the three N.C., and COM contacts are connected so that they short, a R circuit must never be designed to allow R2 the possibility of burning or generating 1) R1, R2 : Contacts for R an overcurrent. R : Double pole relay 3) A forward and reverse motor rotation Fig. 19 Bad example of form A and B use circuit using switching of form A and B contacts must never be designed.
Commercial AC power Home AC generator Load
R1 N.C. N.O. COM M Load R Relay coil R2 2) 3) R1, R2 : Contacts for R R : Double pole relay Push-botton switch
· Shorts Between Different Electrodes Although there is a tendency to select miniature control components because of the trend toward miniaturizing electrical control units, care must be taken when selecting the type of relay in circuits where different voltages are applied
between electrodes in a multi-pole relay, especially when switching two different power supply circuits. This is not a problem that can be determined from sequence circuit diagrams. The construction of the control component itself must If set coils or reset coils are to be connected together in parallel, connect a diode in series to each coil. Fig. 20 (a) (b) Also, if the set coil of a relay and the reset coil of another relay are connected in parallel, connect a diode to the coils in series. (c) If the set coil or reset coil is to be connected in parallel with an inductive load (e.g. another electromagnetic relay coil, motor, transformer, etc.), connect a diode to the set coil or reset coil in series. (d)
be examined and sufficient margin of safety must be provided especially in creepage between electrodes, space distance, presence of barrier, etc.
LATCHING RELAYS
· Latching relays are shipped from the factory in the reset state. A shock to the relay during shipping or installation may cause it to change to the set state. Therefore, it is recommended that the relay be used in a circuit which initializes the relay to the required state (set or reset) whenever the power is turned on. · Avoid impressing voltages to the set coil and reset coil at the same time. · Connect a diode as shown since latching may be compromised when the relay is used in the following circuits.
(a) Parallel connection of set coils (+) S1 S2 S3
Use a diode having an ample margin of safety for repeated DC reverse voltage and peak reverse voltage applications and having an average rectified current greater than or equal to the coil current. · Avoid applications in which conditions include frequent surges to the power supply. · Avoid using the following circuit since self-excitation at the contacts will inhibit the normal keep state. (Fig. 21)
(b) Parallel connection of set coils (+) S1 S2 S3
RL Reset coil Set coil Set coil Reset coil Set coil Reset coil Set coil Reset coil
RL : Latching relay RLa : Form A contacts of RL RLb : Form B contacts of RL
Bad example
Fig. 21
(-) Diode connection Diode connection (-) Diode connection Diode connection
(c) Parallel connection of set coils and reset coils (+) S1 S2 S3 (+)
(d) Circuit with inductive load in parallel with the set coil or reset coil S
Reset coil Set coil Set coil
Reset coil
AC or DC Set or reset coil
Motor M Common relay coil
(-) Diode connection Diode connection Diode connection
· Four-Terminal Latching Relay In the 2 coil latching type circuit in Fig. 22, one terminal at one end of the set coil and one terminal at one end of the reset coil are connected in common and voltages of the same polarity are applied to the other side for the set and reset operations. In this type of circuit, short 2 terminals of the relay as noted in the next table. This helps to keep the insulation high between the two winding.
Fig. 20
General Application Guidelines
Set switch Reset coil
Set coil
Reset switch
Fig. 22
Relay Type DX NR DR 1c DS 2c 4c NL Flat NC Slim ST SP
Terminal Nos. 5 & 11 3&6 3&6 - 15 & 16 4&5 3&4 3&4 2&4
Notes: 1. DS4c and ST relays are constructed so that the set coil and reset coil are separated for high insulation resistance. 2. DSP, RG, TQ, TQ-SMD, TF, TN, TX series, DF, and S relays are not applicable due to polarity.
HANDLING CAUTIONS FOR TUBE PACKAGING
Some types of relays are supplied in tube packaging. If you remove any relays from the tube packaging, be sure to slide the stop plug at one end to hold the remaining relays firmly together so they would not move in the tube. Failing to do this may lead to the appearance and / or performance being damaged.
Slide in the plug.
Stop plug
AMBIENT ENVIRONMENT
1. Ambient Temperature and Atmosphere Be sure the ambient temperature at the installation does not exceed the value listed in the catalog. Furthermore, environmentally sealed types (plastic sealed type, metallic hermetic seal type) should be considered for applications in an atmosphere with dust, sulfur gases (SO2, H2S), or organic gases. 2. Silicon Atmosphere Silicon-based substances (silicon rubber, silicon oil, silicon-based coating material, silicon caulking compound, etc.) emit volatile silicon gas. Note that when silicon is used near relay, switching the contacts in the presence of its gas causes
perature. Use within the range indicated in the graph below. 2) Condensation Condensation forms when there is a sudden change in temperature under high temperature, high humidity conditions Condensation will cause deterioration of the relay insulation. 3) Freezing Condensation or other moisture may freeze on the relay when the temperatures is lower than 0°C 32°F. This causes problems such as sticking of movable parts or operational time lags. 4) Low temperature, low humidity environments The plastic becomes brittle if the relay is exposesd to a low temperature, low humidity environment for long periods of time.
ENVIRONMENTALLY SEALED TYPE RELAYS
85 Tolerance range (Avoid freezing when (Avoid used at temperatures condensation when lower than 0°C32°F) used at temperatures higher than 0°C32°F) 5 -40 -40 0 +32 Temperature, °C °F +70 +158
· Pressure: 86 to 106 kPa The humidity range varies with the temperature. Use within the range indicated in the graph below.
General Application Guidelines
PROCESSING CONSIDERATIONS
MOUNTING CONSIDERATIONS
· Top View and Bottom View Relays used for PC boards, especially the flat type relays, have their top or bottom surface indicated in the terminal wiring diagrams. Relay with terminals viewed from the bottom (terminals cannot be seen from the top) Relay with terminals viewed from the top (all terminals can be seen from the top) Note during PC board pattern design (NL, NC) · Mounting Direction Mounting direction is important for optimum relay characteristics. · Shock Resistance It is ideal to mount the relay so that the movement of the contacts and movable parts is perpendicular to the direction of vibration or shock. Especially note that the vibration and shock resistance of Form B contacts while the coil is not excited is greatly affected by the mounting direction of the relay. · Contact Reliability
METHOD OF MOUNTING
· The direction of mounting is not specifically designated, but to the extent possible, the direction of contact movement should be such that vibration and shock will not be applied. When a terminal socket is used · After drilling the mounting holes, the terminal socket should be mounted making certain the mounting screws are not loose. DIN standard sockets are available for one-touch mounting on DIN rail of 35mm 1.378 inch width.
Fig. 23
General Application Guidelines
When reversible terminal sockets are used · The reversible terminal sockets (HC, HL socket) are for one-touch mounting. (A panel thickness of 1 to 2mm .039 to .079 inch should be used.) (Fig. 23) · The socket should be pushed through the opening in the mounting panel until the projections on the side of the mounting bracket extend out over the back surface. (Fig. 24) · When the terminal board uses screw fastening connections, either pressure terminals or other means should be used to make secure fastening of the wire. · Connections to Wrapping Socket Applicable Wire Type Solid wires with diameters of 0.26 to 0.65 mm .010 to .026 inch are applicable to wrapping terminals (0.5 mm .020 inch type is standard). Tinned copper wires are the most suitable for this purpose. Solid bare copper, brass, or nickel wires can also be used. Never use stranded wires for wrapping sockets. Winding a Wire A wire may be would on a wrapping terminal in two ways: i.e. only the stripped conductor is would, or a single turn of coated wire is wrapped together with the stripped conductor. The later type of winding is suitable for wire diameters of 0.32 mm .013 inch or less. Unwrapping a Wire When unwinding a wire from a wrapping terminal, use a commercially available unwrapping tool. For wrapping conditions, bits and sleeves, refer to table. The chassis cutout is identical to that for the existing HC socket. The HC socket mounting track and hold down clip can also be used. Relay Types Applicable to Wrapping Socket (with hold down clip) The HC wrapping socket with hold down clip can be used for the standard-type HC relays, HC relays with LED indication and HC latching relays. When using the standard wrapping socket for the HC relays with LED indication or HC latching relays, use the special hold down clip supplied with the socket (see table).
Fig. 24
· When all four of the projections are visible from the back side of the mounting panel, the mounting is completed and the socket is fastened. · To remove the socket, the projections on the side of the mounting bracket should be pushed inward and at the same time the body of the socket should be pushed lightly from the back side. The socket can then be removed from the panel. · The socket should be inserted through the opening in the mounting panel so that the terminal wiring side is toward the back side. The mounting panel can be used for 10 units, but it can be cut for use with less than that number. (Fig. 25)
Conductor winding
Coated wire winding
· Wire Wrapping Condition, Bits and Sleeves
Item Wire size dia. (mm inch) 0.26 .010 Stripping length (mm inch) Wrapping type Typical Pulling wrapping strength turns (kgf) 9 0.5 to 2 Bit type 36-A 37-A 3-A 21-A 8 3 to 5 25-A 34-A 43-A 1-A 22-A 26-A 6 3 to 6 33-A 34-A 40-A 45-A 2-A 23-A 6 4 to 10 40-A 44-A 46-A Sleeve time 5-B 5-B 1-B 1-B 22-B 5-B 1-B 1-B 2-B 22-B 1-B 5-B 1-B 20-B 2-B 20-B 1-B 2-B 20-B
Coated wire winding 40 to 41 1.575 to 1.614 Coated wire winding Conductor winding Coated wire winding 43 to 44 Conductor winding 1.693 to 1.732 Conductor winding Coated wire winding Conductor winding Coated wire winding
Fig. 25
REGARDING CONNECTION OF LEAD WIRES
· When making the connections, depending upon the size of load, the wire crosssection should be at least as large as the values shown in the table below.
Permissible current Cross-section (mm2) 2 3 5 7.5 12.5 15 20 30 0.2 0.3 0.5 0.75 1.25 2 2 3.5
Conditions 0.5 .020
Conductor winding 36 to 37 1.417 to 1.457 Conductor winding Conductor winding Conductor winding Coated wire winding Conductor winding Coated wire winding 0.65 .026 41 to 42 1.614 to 1.654 Conductor winding Conductor winding Coated wire winding
· Wrapping Sockets and Applicable Relay Types
Socket type Standard wrapping socket Wrapping socket with hold down clip Applicable relays Standard HC relays (including amber type) HC relays with LED indication (use accessory hold down clip) HC latching relays (use accessory hold down clip) HC relays with LED indication HC latching relays
General Application Guidelines
CAUTIONS FOR USE-Check List
Check Item
Coil Drive Input
Load (Relay contacts)
Circuit Design
Operating Environment
Installation and Connection
Reliability
Reliability (broad sense)
1. Reliability (narrow sense), durability Long life time: MTTF, B10, R(T), Low failure rate: Lamda (), MTBF 2. Maintainability MTTR Preventive maintenance, predicted maintenance 3. Design reliability Human factor, redundancy, fool-proof, fail-safe
Availability
· Reliability Measures The following list contains some of the most popular reliability measures:
Reliability
Failure rate
where
m: figure parameter : Measurement parameter : Position parameter
The Weibull probability chart is a simpler alternative of complex calculation formulas. The chart provides the following advantages: (1) The Weibull distribution has the closest proximity to the actual failure rate distribution. (2) The Weibull probability chart is easy to use. (3) Different types of failures can be identified on the chart.
Failure rate
Applications of Relays in Electronic Circuits
RELAY DRIVE BY MEANS OF A TRANSISTOR
· Connection method The voltage impressed on the relay is always full rated voltage, and in the OFF time, the voltage is completely zero for avoidance of trouble in use. (Fig. 1)
(Good) Collector connection With this most common connection, opertion is stable.
Fig. 1
(Care) Emitter connection When the circumstances make the use of this connection unavoidable, if the voltage is not completely impressed on the relay, the transistor does not conduct completely and operation is uncertain.
(Care) Parallel connection When the power consumed by the complete circuit becomes large, consideration of the relay voltage is necessary.
· Countermeasures for surge voltage of relay control transistor If the coil current is suddenly interrupted, the counter emf. a sudden high voltage pulse is develAs suitable ratings for this diode, the curoped in the coil. If this voltage exceeds rent should be equivalent to the average the voltage resistance of the transistor, rectified current to the coil, and the the transistor will be degraded, and this inverse blocking voltage should be about will lead to damage. It is absolutely nec3 times the value of the power source essary to connect a diode in the circuit voltage. (Fig. 2) as a means of preventing damage from
Diode
Fig. 2
Take care of ASO.
· Snap action (Characteristic of relay with voltage rise and fall of voltage) Unlike the characteristic when voltage is impressed slowly on the relay coil, this is the case where it is necessary to impress the rated voltage in a short time and also to drop the voltage in a short time. (Fig. 3)
Fig. 3
Non-pulse signal
Pulse signal (square wave)
ON Ry OFF (No Good) Without snap action (Good) Snap action
· Schmitt circuit (Snap action circuit) (Wave rectifying circuit) When the input signal does not produce a snap action, ordinarily a Schmitt trigger circuit is used to produce safe snap action. Characteristic points 1. The common emitter resistor RE must have a value sufficiently small compared with the resistance of the relay coil. (The voltage impressed on the relay must not be greater than the excitation voltage.) 2. Due to the relay coil current, the difference in the voltage at point P when T2 is
conducting and at point P when T1 is conducting creates hysteresis in the detection capability of Schmitt circuit, and care must be taken in setting the values. 3. When there is chattering in the input signal because of waveform oscillation, an RC time constant circuit should be inserted in the stage before the Schmitt trigger circuit. (However, the response speed drops.) (Fig. 4)
R1 Signal
R2 Tr2
Applications of Relays in Electronic Circuits
· Avoid Darlington circuit connections. (High amplification) This circuit is a trap into which it is easy to fall when dealing with high circuit technology. This does not mean that it is immediately connected to the defect, but it is linked to troubles that occur after long periods of use and with many units in operation. (Fig. 5)
(No good) Darlington connection
Fig. 5
(· Due to excessive consumption of power, heat is generated.) (· A strong T1, is necessary.)
(Good) Emitter connection
(T2 conducts completely.) (T1 is sufficient for signal use.)
Fig. 6 Connection to the next stage through collector
IO: dark current (No good)
RELAY DRIVE BY MEANS OF SCR
· Ordinary drive method For SCR drive, it is necessary to take particular care with regard to gate sensitivity and erroneous operation due to noise. (Fig. 7) · Caution points regarding ON / OFF control circuits peak values and it can occur only at zero (When used for temperature or similar phase values as a phenomenon this type control circuits) of control. (Depending upon the sensitivity When the relay contacts close simultaneand response speed of the relay) ously with an AC single phase power 4. Accordingly, either an extremely long source, because the electrical life of the life or an extremely short life results contacts suffers extreme shortening, care with wide variation, and it is necessary to is necessary. (Fig. 8) take care with the initial device quality 1. When the relay is turned ON and OFF check. using a SCR, the SCR serves as a half wave power source as it is, and there are ample cases where the SCR is easily Fig. 8 restored. Ry 2. In this manner the relay operation and restoration timing are easily synchronized with the power source frequency, and the Ry S timing of the load switching also is easily synchronized. 3. When the load for the temperature control is a high current load such as a heater, the switching can occur only at
Heater
RGK IGT : There is no problem even with more than 3 times the rated current. RGK : 1K ohms must be connected. R, C : This is for prevention of isolation point error due to a sudden rise in the power source or to noise. (dv / dt countermeasure)
Fig. 7
RELAY DRIVE FROM EXTERNAL CONTACTS
Relays for PC board use have high sensitivity and high speed response characteristics, and because they respond sufficiently to chattering and bouncing, it is necessary to take care in their drive. When the frequency of use is low, with the delay in response time caused by a condenser, it is possible to absorb the chattering and bouncing. (Fig. 9) (However, it is not possible to use only a condenser. A resistor should also be used with the capacitor.)
Ry External contact
Fig. 9
Applications of Relays in Electronic Circuits
LED SERIES AND PARALLEL CONNECTIONS
1. In series with relay 2. R in parallel with LED 3. In parallel connection with relay
Power consumption: In common with relay (Good) Defective LED: Relay does not operate (No good) Low voltage circuit: With LED, 1.5V down (No good) No. of parts: (Good)
Power consumption: In common with relay (Good) Defective LED: Relay operate (No good) Low voltage circuit: With LED, 1.5V down (No good) No. of parts: R1 (Care)
Power consumption: Current limiting resistor R2 (Care) Defective LED: Relay operate stable (Good) Low voltage circuit: (Good) No. of parts: R2 (Care)
ELECTRONIC CIRCUIT DRIVE BY MEANS OF A RELAY
· Chatterless electronic circuit Even though a chatterless characteristic is a feature of relays, this is to the fullest extent a chatterless electrical circuits, much the same as a mercury relay. To meet the requirement for such circuits as the input to a binary counter, there is an electronic chatterless method in which chattering is absolutely not permissible. Even if chattering develops on one side, either the N.O. side contacts or the N.C. side contacts, the flip flop does not reverse, and the counter circuit can be fed pulsed without a miss. (However, bouncing from the N.O. side to N.C. side must be absolutely avoided.) (Fig. 10) · Triac drive When an electronic circuit using a direct drive from a triac, the electronic circuit will not be isolated from the power circuit, and because of this, troubles due to erroneous operation and damage can develop easily. The introduction of a relay drive is the most economical and most effective solution. (Photo coupler and pulse transformer circuits are complicated.) When a zero cross switching characterisNotes: 1. The A, B, and C lines should be made as short as possible. 2. It is necessary that there be no noise from the coil section induced into the contact section. Ry A
B R-S-F.F
Binary Counter
Fig. 10
tic is necessary, a solid state relay (SSR) should be used. (Fig. 11)
Fig. 11
ASSURANCE OF POWER SOURCE FOR RELAY AND ELECTRONIC CIRCUIT
· Constant Voltage circuit and PC board pattern Ordinarily, it is extremely undesirable to have ripple and voltage variation in an electronic circuit power source. This is naturally true also for relay power sources but not to the same extent as for the electronic circuit. Accordingly, it is desirable to have a constant voltage circuit for dedicated use of the electronic circuit with a sufficient margin of current. Roughly speaking, this is also good for the relay, but from a practical
Regular circuit (Example) Relay power supply Regular circuit Regulated power supply or voltage stabilizer. Electronic circuit
Fig. 12
Applications of Relays in Electronic Circuits
viewpoint, the relay should be operated within the standards set for ripple and voltage variation. Similarly, in the circuit diagram shown in Fig. 12, but means of · Prevention of Voltage Drop Due to Rush Current In the circuit shown in Fig. 13 (a), rush current flows from the lamp or capacitor. The instant the contacts close, the voltage drops and the relay releases or chatters. the manner in which the PC board pattern is designed, the ON / OFF operation of the relay coil, lamp, etc., will exert no influence on the electronic circuit. This is just a matter of technique that is necessary.
Ry Battery
Motor
Fig. 13
PC BOARD DESIGN CONSIDERATIONS
· Pattern Layout for Relays Since relays affect electronic circuits by generating noise, the following points should be noted. Keep relays away from semiconductor devices. Design the pattern traces for shortest lengths. Place the surge arrester (diode, etc.) near the relay coil. Avoid routing pattern traces susceptible to noise (such as for audio signals) underneath the relay coil section. Avoid through-holes in places which cannot be seen from the top (e.g. at the base of the relay). Solder flowing up through such a hole may cause damage such as a bro· When it is necessary to use hand soldering for one part of a component after dip soldering has been done By providing a narrow slot in the circular part of the foil pattern, the slot will prevent the hole from being plugged with solder. (Fig. 15)
(No good)
Diode bridge Relay coil Ry A Diode bridge
(Good)
Co Constant voltage
Electronic circuit
Relay currents and electronic circuit currents flow together through A and B.
Fig. 14
Constant Electronic circuit voltage Tr B2 ·Relay coil currents consist only of A1, and B1. ·Electronic circuit currents consist only of A2 and B2. A simple design consideration can change the safety of the operation.
ken seal. Even for the same circuit, pattern design considerations which minimize the influence of the on / off opera-
tions of the relay coil and lamp on other electronic circuits are necessary. (Fig. 14)
· When the printed circuit board itself is used as a connector 1 The edge should be beveled. (This 2 When only a single side is used as prevents peeling of the foil when the the connector blade, if there is distortion board is inserted into its socket.) in the circuit board, contact will be defective. Care should be taken. (Fig. 16)
Through hole
Fig. 15
0.3 to 0.5mm .012 to .020 inch
Fig. 16
Bevel of radius
(Care)
(Good)
(Good) Contact on both surfaces
Applications of Relays in Electronic Circuits
PC BOARD REFERENCE DATA
Fig. 17
10 Copper foil 9 0.0018mm .0007 inch 8 7 Current, A 6 5 4 3 2 1 0 0 0.2 0.5 1.0 1.5 2.0 2.5 3.0 0 .008 .020 .039 .059 .079 .098 .118 Conductor width, mm inch 60°C 140°F 40°C 104°F 20°C 68°F 10°C 50°F
Fig. 18
10 Copper foil 9 .035mm .001 inch 8 7 Current, A 6 5 4 3 2 1 0 0 0.2 0.5 1.0 1.5 2.0 2.5 3.0 0 .008 .020 .039 .059 .079 .098 .118 Conductor width, mm inch 20°C 68°F 10°C 50°F
· Conductor width The allowable current for the conductor was determined from the safety aspect ane the effect on the performance of the conductor due to the rise in saturation temperature when current is flowing. (The narrwer the conductor width and the thinner the copper foil, the larger the temperature rise.) For example, too high a rise in temperature causes degradation of the characteristic and color changes of the laminate. Ingeneral, the allowable current capacity of the conductor is determined so that the rise is temperature is less than 10 degrees C. It is necessary to design the conductor width from this allowable conductor current capacity. Fig. 17, Fig. 18, Fig. 19 show the relationship between the current and the conductor width for each rise in temperature for different copper foils. It is also necessary to give consideration to preventing abnormal currents from exceeding the destruction current of the conductor. Fig. 21 shows the relationship between the conductor width and the destruction current.
60°C 140°F 40°C 104°F
Fig. 19
14 Copper foil 13 .070mm 60°C 140°F 12 .003 inch 11 40°C 104°F 10 9 8 20°C 68°F 7 6 10°C 50°F 5 4 3 2 1 0 0 0.5 1.0 1.5 2.0 2.5 3.0 0 .020 .039 .059 .079 .098 .118 Conductor width, mm inch
Fig. 20
40 35 Destruction current, A 30 25 20 15 10 5 0 0 0 0.5 1.0 1.5 2.0 2.5 3.0 .020 .039 .059 .079 .098 .118 Conductor width, mm inch Copper foil thick .070 .003
Current, A
Fig. 21
· Hole and land diameter The hold diameter and land are made with the hole slightly larger than the lead wire so that the component may be inserted easily. Also, when soldering, the solder will build up in an eyelet condition, increasing the mounting strength. The standard dimensions for the hold diameter and land are shown in the table below.
mm inch
Remarks 1. The hole diameter is made 0.2 to 0.5mm larger than the lead diameter. However, if the jet method (wave type, jet type) of soldering is used, because of the fear of solder passing through to the component side, it is more suitable to make the hold diameter equal to the lead diameter +0.2mm. 2. The land diameter should be 2 to 3 times the hold diameter. 3. Do not put more than 1 lead in one hole.
Land diameter 2.0 to 3.0 .079 to .118 3.5 to 4.5 .138 to .177
Applications of Relays in Electronic Circuits
Fig. 22
Example : As shwon is the drawing below, the 150mm 5.906 inch direction is taken as the longitudinal direction. Longitudinal 150 5.906
Longitudinal direction
Also, as shown in the drawing below, when the pattern has a connector section, the direction is taken as shown by the arrow in the longitudinal direction
Longitudinal direction
6.0 5.0 Destruction Voltage (kV) 4.0 3.0 2.0 1.0 0
0 0.2 0.5 1.0 2.0 3.0 0 .008 .020 .039 .079 .118 Conductor width mm inch
Fig. 23
Table 1. Example of conductor spacing design Maximum DC and AC Minimum Conductor VoltageBetween Spacing (mm) Conductors(V) 0 to 50 51 to 150 151 to 300 301 to 500 500 to more 0.381 0.635 1.27 2.54 Calculated at 1011508 mm / V
Relay Soldering and Cleaning Guidelines
1. Mounting of Relay · Avoid bending the terminals to make the relay self-clinching. Relay performance cannot be guaranteed if the terminals are bent. Self-clinching terminal types are available depending on the type of relay. · Correctly drill the PC board according to the given PC board pattern illustration. · Stick packaging for automatic mounting is available depending on the type of relay.
Bad example
2. Flux Application
· Adjust the position of the PC board so that flux does not overflow onto the top of it. This must be observed especially for dust-cover type relays. · Use rosin-based non-corrosive flux. · If the PC board is pressed down into a flux-soaked sponge as shown on the right, the flux can easily penetrate a dust-cover type relay. Never use this method. Note that if the PC board is pressed down hard enough, flux may even penetrate a flux-resistant type relay.
Bad example
3. Preheating
· Be sure to preheat before using automatic soldering. For dust-cover type relays and flux-resistant type relays, preheating acts to prevent the penetration of flux into the relay when soldering. Solderability also improves. · Preheat according to the following conditions.
Temperature Time 100°C 212°F or less Within approx. 1 minute
· Note that long exposure to high temperatures (e.g. due to a malfunctioning unit) may affect relay characteristics.
4. Soldering
Automatic Soldering · Flow solder is the optimum method for soldering. · Adjust the level of solder so that it does not overflow onto the top of the PC board. · Unless otherwise specified, solder under the following conditions depending on the type of relay.
Solder Temperature Approx. 250°C 482°F
Hand Soldering · Keep the tip of the soldering iron clean.
Soldering Iron Iron Tip Temperature 30W to 60W Approx. 300°C 572°F
Soldering Time Within approx. 3 seconds Solder JIS Z3282 H60 or H63
Soldering Time Within approx. 5 seconds Solder JIS Z3282 H60 or H63
Relay Soldering and Cleaning Guidelines
5. Cooling Automatic Soldering · Immediate air cooling is recommend to prevent deterioration of the relay and surrounding parts due of soldering heat. · Although the environmentally sealed type relay (plastic sealed type, etc.) can be cleaned, avoid immersing the relay into cold liquid (such as cleaning solvent) immediately after soldering. Doing so may deteriorate the sealing performance. Hand Soldering
6. Cleaning
· Do not clean dust-cover type relays and flux-resistant type relays by immersion. Even if only the bottom surface of the PC board is cleaned (e.g. with a brush), careless cleaning may cause cleaning solvent to penetrate the relay. · Plastic sealed type relays can be cleaned by immersion. Use alcoholbased cleaning solvents. Use of other cleaning solvents (e.g. Trichlene, chloroethene, thinner, benzyl alcohol) may damage the relay case. However, some types of relays use materials which · If the PC board is to be coated to prevent the insulation of the PC board from deteriorating due to corrosive gases and high temperatures, note the following. · Do not coat dust-cover type relays and flux-resistant type relays, since the coating material may penetrate the relay and cause contact failure. Or, mount the relay
Type Epoxy-base Urethane-base Suitability for Relays Good Care
are chemical resistant. Select the suitable relay or solvent by referring to the cleaning solvent compatibility chart below. · Cleaning with the boiling method is recommended. Avoid ultrasonic cleaning on relays. Use of ultrasonic cleaning may cause breaks in the coil or slight sticking of the contacts due to ultrasonic energy.
7. Coating
after coating. · Depending on the type, some coating materials may have an adverse affect on relays. Furthermore, solvents (e.g. xylene, toluene, MEK, I.P.A.) may damage the case or chemically dissolve the epoxy and break the seal. Select coating materials carefully.
Features
·Good electrical insulation. ·Although slightly difficult to apply, does not affect relay contacts. ·Good electrical insulation, easy to apply. ·Solvent may damage case. Check before use. ·Good electrical insulation, easy to apply. ·Silicon gas becomes the cause of contact failure. ·Do not use on dust-cover type relays and flux-resistant type relays. Can be used on only metallic hermetic sealed typ