Precautions for Correct Use of General-purpose Relays

Refer to the Safety Precautions section for each Relay for specific precautions applicable to that Relay.

1.Using Relays

When actually using Relays, unanticipated failures may occur. It is therefore essential to test the operation is as wide of range as possible.

Unless otherwise specified in this catalog for a particular rating or performance value, all values are based on JIS C5442 standard test conditions (temperature: 15 to 35°C, relative humidity: 25% to 75%, air pressure: 86 to 106 kPa). When checking operation in the actual application, do not merely test the Relay under the load conditions, but test it under the same conditions as in the actual operating environment and using the actual operating conditions.

The reference data provided in this catalog represent actual measured values taken from samples of the production line and shown in diagrams. They are reference values only.

Ratings and performance values given in this catalog are for individual tests and do not indicate ratings or performance values under composite conditions.

2.Selecting Relays

(1)Mounting Structure and Type of Protection

2.-(1)-1 Type of Protection

If a Relay is selected that does not have the appropriate type of protection for the atmosphere and the mounting conditions, it may cause problems, such as contact failure.

Refer to the type of protection classifications shown in the following table and select a Relay suitable to the atmosphere in which it is to be used.

Classification by Type of Protection

2.-(1)-2 Combining Relays and Sockets

Use OMRON Relays in combination with specified OMRON Sockets. If the Relays are used with sockets from other manufacturers, it may cause problems, such as abnormal heating at the mating point due to differences in power capacity and mating properties.

2.-(1)-3 Using Relays in Atmospheres Subject to Dust

If a Relay is used in an atmosphere subject to dust, dust will enter the Relay, become lodged between contacts, and cause the circuit to fail to close. Moreover, if conductive material such as wire clippings enter the Relay, it will cause contact failure and short-circuiting.

Implement measures to protect against dust or use a sealed Relay as required by the application.

2.-(1)-4 Exporting to Tropical Zones

Use the following types of Relays if they are to be exported to tropical zones.

High-humidity Relays

Plastic-sealed Relays

Hermetically Sealed Relays

Using other types of Relays may result in operating problems because of rusted metal parts.

(2)Drive Circuits

2.-(2)-1 Operating Form

Relays are divided into the following classifications by operating form. Select the appropriate Relay to match the intended purpose.

Basic Operation of Special-purpose Relays

2.-(2)-2 Coil Specifications

Correctly select the coil specifications to match the design circuit. If unsuitable coil specifications are selected, the performance potential will not be attainable, and application of overvoltage may cause coil burnout.

2.-(2)-3 AC Coil Specifications

Check the applicable power supply for each Relay (e.g., rated voltage and rated frequency) before selecting the AC coil specifications.

Some rated voltages and rated frequencies cannot be used for certain Relays. Improper selection may result in abnormal heat generation or malfunctions.

Example Using 100 VAC

Note:These rating names are not specified by JIS.

2.-(2)-4 Full-wave Rectifying Relays

With DC Relays, the operating voltage fluctuates with the ripple factor and this fluctuation may cause humming. Therefore, a smoothing capacitor C is added to the full-wave rectifying power supply circuit to reduce the ripple factor. Full-wave Rectifying Relays will not produce humming or other problems even on circuits with no smoothing capacitor C. Also, a full-wave rectified 100-V AC power supply can be directly input to a coil with 100-V DC specifications for a Full-wave Rectifying Relay.

2.-(2)-5 Providing Power Continuously for Long Periods

A non-energized design is desirable, for example, if a Relay is used in a circuit with power provided for an extended period without switching the Relay (such as for error evaluation circuits or fault indicator alarm devices that reset only when an error occurs and generate an alarm on the NC contact). If power is continuously provided to the coil for an extended period, deterioration of coil insulation will be accelerated due to heating of the coil. Also see 3.-(2)-7 Using with Infrequent Switching.

2.-(2)-6 Operation Checks for Inspection and Maintenance

Relay models are available that indicate the operating status either with visual or mechanical indications when the Relay is operating.

Note:The built-in indicator shows that power is being provided to the Rating coil. The indicator is not based on contact operation.

(3)Loads

2.-(3)-1 Contact Ratings

Contact ratings are generally shown for resistance loads and inductive loads. The contact method and contact material are also listed. Select the appropriate model based on the load and required service life.

2.-(3)-2 Switching Capacity

Check the maximum switching capacity on the graph for Relays to select a Relay that suits the application. Use the graphs for maximum switching capacity and endurance as a rough guide for selection. The resulting values, however, are only rough guides, so be sure to confirm operation using the actual equipment. A description of how to read the graphs for maximum switching capacity and endurance is provided below.

For example, when switching voltage V₁ is known, maximum switching current I₁ can be obtained from the point of intersection on the characteristic curve. Conversely, maximum switching voltage V₁ can be obtained if I₁ is known. The number of operations can then be obtained using the Endurance Curve from the value obtained for I₁.

For a case such as the following:
If the contact voltage = 40 V, the contact switching current = 2 A (*1).
The number of operations with a maximum contact voltage of 2 A is approximately 300,000 (*2).

Maximum Switching Capacity

Endurance Curve

2.-(3)-3 Using Relays with a Microload

If a Relay is to be used for a microload, select an appropriate model taking into account the type of load, contact material, and contact method.

If a Relay is to be used for a microload, the reliability will depend on the contact material and contact method. For example, twin contacts are more reliable than single contacts simply because of the parallel redundancy they provide.

2.-(3)-4 Contact Material

The following table gives the features of contact materials. Refer to this table when selecting Relays.

Contact Materials and Their Features

2.-(3)-5 Contact Certification Ratings for Standards

The rated contact values stamped on models with certified standards are the certification rating values for the standards. Individually specified Relay rating values, however, depend on the model. Be sure to confirm the ratings and number of operations for each Relay and use the Relay within ratings specified by OMRON.

3.Circuit Design

(1)Load Circuits

3.-(1)-1 Load Switching

In actual Relay operation, the switching capacity, electrical durability, and applicable load will vary greatly with the type of load, the ambient conditions, and the switching conditions. Confirm operation under the actual conditions in which the Relay will be used.

The maximum switching capacity for Relays is shown in the following graph.

Maximum Switching Capacity

Switching Section (Contact Section)

(1)Resistive Loads and Inductive Loads

The switching power for an inductive load will be lower than the switching power for a resistive load due to the influence of the electromagnetic energy stored in the inductive load.

(2)Switching Voltage (Contact Voltage)

The switching power will be lower with DC loads than it will with AC loads. In the example in the figure above, W_max. of the higher voltage side^*2 (75 W) is lower than W_max. of the lower voltage side^*1 (300 W). This difference is the amount that switching performance decreases because the contact voltage is high. Applying voltage or current between the contacts exceeding the maximum values will result in the following:

1.The carbon generated by load switching will accumulate around the contacts and cause deterioration of insulation.

2.Contact deposits and locking will cause contacts to malfunction.

(3)Switching Current

Current applied to contacts when they are open or closed will have a large effect on the contacts. For example, when the load is a motor or a lamp, the larger the inrush current, the greater the amount of contact exhaustion and contact transfer will be, leading to deposits, locking, and other factors causing the contacts to malfunction. (Typical examples illustrating the relationship between load and inrush current are given below.)

If a current greater than the rated current is applied and the load is from a DC power supply, the connection and shorting of arcing contacts will result in the loss of switching capability.

DC Loads and Inrush Current

AC Loads and Inrush Current

3.-(1)-2 Electrical Durability

Electrical durability will greatly depend on factors such as the coil drive circuit, type of load, switching frequency, switching phase, and ambient atmosphere. Therefore be sure to check operation in the actual application.

3.-(1)-3 Failure Rates

The failure rates provided in this catalog are determined through tests performed under specified conditions. The values are reference values only. The values will depend on the operating frequency, the ambient atmosphere, and the expected level of reliability of the Relay. Be sure to check relay suitability under actual load conditions.

3.-(1)-4 Surge Suppressors

Using a surge suppressor is effective in increasing contact durability and minimizing the production of carbides and nitric acid. The following table shows typical examples of surge suppressors. Use them as guidelines for circuit design.

1.Depending on factors such as the nature of the load and the Relay characteristics, the effects may not occur at all or adverse effects may result. Therefore be sure to check operation under the actual load conditions.

2.When a contact protection circuit is used, it may cause the release time (breaking time) to be increased. Therefore be sure to check operation under the actual load conditions.

Examples of Surge Suppressors

Do not use a surge suppressor in the manners shown below.

Note:Although it is thought that switching a DC inductive load is more difficult than a resistive load, an appropriate contact protection circuit can achieve almost the same characteristics.

3.-(1)-5 Countermeasures for Surge from External Circuits

Install contact protection circuits, such as surge absorbers, at locations where there is a possibility of surges exceeding the Relay withstand voltage due to factors such as lightning. If a voltage exceeding the Relay withstand voltage value is applied, it will cause line and insulation deterioration between coils and contacts and between contacts of the same polarity.

3.-(1)-6 Connecting Loads for Multi-pole Relays

Connect multi-pole Relay loads according to diagram "a" below to avoid creating differences in electric potential in the circuits. If a multi-pole Relay is used with an electric potential difference in the circuit, it will cause short-circuiting due to arcing between contacts, damaging the Relays and peripheral devices.

3.-(1)-7 Motor Forward/Reverse Switching

Switching a motor between forward and reverse operation creates an electric potential difference in the circuit, so a time lag (OFF time) must be set up using multiple Relays.

3.-(1)-8 Power Supply Double Break with Multi-pole Relays

If a double break circuit for the power supply is constructed using multi-pole Relays, take factors into account when selecting models: Relay structure, creepage distance, clearance between unlike poles, and the existence of arc barriers. Also, after making the selection, check operation in the actual application. If an inappropriate model is selected, short-circuiting will occur between unlike poles even when the load is within the rated values, particularly due to arcing when power is turned OFF. This can cause burning and damage to peripheral devices.

3.-(1)-9 Short-circuiting Due to Arcing between NO and NC Contacts in SPDT Relays

With Relays that have NO and NC contacts, short-circuiting between contacts will result due to arcing if the space between the NO and NC contacts is too small or if a large current is switched.

Do not construct a circuit in such a way that overcurrent and burning occur if the NO, NC, and SPDT contacts are short-circuited.

3.-(1)-10 Using SPST-NO/SPST-NC Contact Relays as an SPDT Relay

Do not construct a circuit so that overcurrent and burning occur if the NO, NC and SPDT contacts are short-circuited. Also, with SPST-NO/SPST-NC Relays, a short-circuit current may flow for forward/reverse motor operation.

Arcing may generate short-circuiting between contacts if there is short-circuiting because of conversion to the MBB contact caused by asynchronous operation of the NO and NC contacts, the interval between the NO and NC contacts is small, or a large current is left open.

3.-(1)-11 Connecting Loads of Differing Capacities

Do not have a single Relay simultaneously switching a large load and a microload. The purity of the contacts used for microload switching will be lost as a result of the contact spattering that occurs during large load switching, and this may give rise to contact failure during microload switching.

3.-(1)-12 Contact Transfer

Contact transfer occurs when switching a DC load when one contact melts or evaporates and transfers to another contact, and results in unevenness as the number of switching operations increase. Eventually, this unevenness becomes locked and appears as if the contacts were welded.

This often occurs in circuits that generate sparks when the contacts are closed, i.e., when the current is large with DC inductive or a capacitive load or when the inrush current is large (e.g. several amps to tens of amps).

Contact protection circuits or contacts made of materials such as AgW or AgCu, which are resistant to transfer, can be used as countermeasures. If this type of load is to be used, it is absolutely necessary to perform tests to confirm operation using the actual equipment.

(2)Input Circuits

3.-(2)-1 Maximum Allowable Voltage

The coil's maximum allowable voltage is determined by the coil temperature increase and the heat withstand temperature of the insulation material. (If the heat withstand temperature is exceeded, it will cause coil burning and layer shorting.) There are also important restrictions imposed to prevent problems such as thermal changes and deterioration of the insulation, damage to other control devices, injury to humans, and fires, so be careful not to exceed the specified values provided in this catalog.

The maximum allowable voltage is the maximum voltage that can be applied to the Relay coil; it is not the continuous allowable value.

3.-(2)-2 Voltage Applied to Coils

Apply only the rated voltage to coils. The Relays will operate at the must-operate voltage or greater, but the rated voltage must be applied to the coils in order to obtain the specified performance.

3.-(2)-3 Changes in Must-operate Voltage Due to Coil Temperature

It may not be possible to satisfy this catalog values for must-operate voltages during a hot start or when the ambient temperature exceeds 23°C, so be sure to check operation under the actual application conditions.

Coil resistance is increased by a rise in temperature causing the must-operate voltage to increase. The resistance thermal coefficient of a copper wire is approximately 0.4% per 1°C, and the coil resistance also increases at this percentage.

This catalog values for the must-operate voltage and must-release voltage are given for a coil temperature of 23°C.

3.-(2)-4 Applied Voltage Waveform for Input Voltage

As a rule, power supply waveforms are based on the rectangular (square) waveforms, and do not operate in such a way that the voltage applied to the coil slowly rises and falls. Also, do not use them to detect voltage or current limit values (i.e., using them for turning ON or OFF at the moment a voltage or current limit is reached).

This kind of circuit causes faulty sequence operations. For example, the simultaneous operability of contacts may not be dependable (for multi-pole Relays, time variations must occur in contact operations), and the must-operate voltage varies with each operation. In addition, the operation and release times are lengthened, causing durability to drop and contact welding. Be sure to use an instantaneous ON/OFF.

3.-(2)-5 Preventing Surges When the Coil Is Turned OFF

Counter electromotive force generated from a coil when the coil is turned OFF causes damage to semiconductor elements and faulty operation.

As a countermeasure, install surge absorbing circuits at both ends of the coil or select a model with a built-in surge absorbing circuit (e.g., the MY, LY, or G2R). When surge absorbing circuits have been installed, the Relay release time will be lengthened, so be sure to check operation using the actual circuits.

External surges must be taken into account for the repetitive peak reverse voltage and the DC reverse voltage, and a diode with sufficient capacity used. Also, ensure that the diode has an average rectified current that is greater than the coil current.

Do not use under conditions in which a surge is included in the power supply, such as when an inductive load is connected in parallel to the coil. Doing so will cause damage to the installed (or built-in) coil surge absorbing diode.

Examples of Models with Built-in Surge Absorbing Circuits

3.-(2)-6 Leakage Current to Relay Coils

Do not allow leakage current to flow to Relay coils. Construct a corrective circuit as shown in examples 1 and 2 below

Example: Circuit with Leakage Current Occurring

Corrective Example 1

Corrective Example 2:
When an Output Value Is Required in the Same Phase as the Input Value

3.-(2)-7 Using with Infrequent Switching

For operations using a microload and infrequent switching, periodically perform continuity tests on the contacts. When switching is not executed for contacts for long periods of time, it causes contact instability due to factors such as the formation of film on contact surfaces.

For operations using a microload and infrequent switching, use Relays with gold-clad bifurcated crossbar contacts and design the circuit with failsafe measures against contact failure and disconnection. The frequency with which the inspections are needed will depend on factors such as the operating environment and the type of load.

3.-(2)-8 Long Wiring Distance from the Power Supply

If the wiring distance (L) from the power supply is long, be sure to measure the voltage at both ends of the Relay coil terminals and set the power supply voltage so that the specified voltage is applied.

Wiring the power supply over a long distance in parallel with power lines may cause reset failure due to voltage generated at both sides of the Relay from float capacitance in the wires when the coil input power supply is OFF.

If reset failure occurs, connect bleeder resistors to both sides of the coil.

Reference Information

Bleeder Resistance for 100/110-VAC MY4

Bleeder Resistance for 200/220-VAC MY4

Note:

1.CVV cable: Nominal conductor cross-section area: 2 mm² (7-conductor), Float capacitance between wires: 0.15 to 0.25 (µF/km).

2.The resistance wattages are reference values. Be sure to check the values in the circuit actually used.

3.-(2)-9 Configuring Sequence Circuits

When configuring a sequence circuit, care must be taken to ensure that abnormal operation does not occur due to faults such as sneak current.

The following figure shows an important procedure when a sequence circuit is made. Always have the upper of the two power supply lines be the positive and the lower lines be the negative. (The concept is the same an AC circuit.) Always connect the contact circuit (e.g., Relay contact) to the positive side.

To the negative side, connect the load circuit, such as a relay coil, timer coil, magnet coil, or solenoid coil.

The following diagram shows an example of sneak current. After contacts A, B, and C are closed causing Relays X1, X2, and X3 to operate, and then contacts B and C are opened, a series circuit is created from A to X1 to X2 to X3. This causes the Relay to hum or to not release.

The following diagram shows an example of a circuit that corrects the above problem. Also, in a DC circuit, the sneak current can be prevented by means of a diode.

3.-(2)-10 Individual Specifications for Must-operate/release Voltages and Operate/Release Times

If it is necessary to know the individual specifications of characteristics, such as must-operate voltages, must-release voltages, operate times, and release times, please contact your OMRON representative.

3.-(2)-11 Using DC-operated Relays
1) Input Power Supply Ripple

For a DC-operated Relay power supply, use a power supply with a maximum ripple percentage of 5%. An increase in the ripple percentage will cause humming.

3.-(2)-12 Using DC-operated Relays
2) Coil Polarity

To make the correct connections, first check the individual terminal numbers and applied power supply polarities provided in this catalog.

If the polarity is connected in reverse for the coil power supply when Relays with surge suppressor diodes or Relays with operation indicators are used, it can cause problems such as Relay malfunctioning, damage to diodes, or failure of indicators. Also, for Relays with diodes, it can cause damage to devices in the circuit due to short-circuiting.

Polarized Relays that use a permanent magnet in a magnetic circuit will not operate if the power supply to the coil is connected in reverse.

3.-(2)-13 Using DC-operated Relays
3) Coil Voltage Insufficiency

If insufficient voltage is applied to the coil, either the Relay will not operate or operation will be unstable. This will cause problems such as a drop in the electrical durability of the contacts and contact welding.

In particular, when a load with a large surge current, such as a large motor, is used, the voltage applied to the coil may drop when a large inrush current occurs to operate the load as the power is turned ON.

Also, if a Relay is operated while the voltage is insufficient, it will cause the Relay to malfunction even at vibration and shock values below the specifications specified in the specification sheets and this catalog. Therefore, be sure to apply the rated voltage to the coil.

3.-(2)-14 Using AC-operated Relays
1) Input Power Supply Voltage Oscillation

Set the power supply voltage fluctuation so that sufficient voltage is supplied to the coils for the Relays to operate completely. If a voltage is applied continuously to a coil that does not enable the Relay to operate completely, the coil may burn due to abnormal heating.

When motors, solenoids, or transformers are connected to the same power lines as those of the power supply of the control circuit of a Relay, the supply voltage to the Relay may drop when these devices operate, causing the Relay to vibrate and the contacts to burn, fuse together, or lose self-held status.

This is particularly likely when a small or small-capacity transformer is connected to the Relay, when the wiring length is too long, or when household or commercial cables small in diameter are used.

If this type of problem occurs, use a synchroscope or other instrument to adjust the voltage fluctuation, and take appropriate countermeasures, such as employing Special Relays having operation characteristics suitable to the environments of your application, and changing the Relay circuit into a DC circuit like the one shown below to absorb the fluctuations in the voltage by using a capacitor.

3.-(2)-15 Using AC-operated Relays
2) Operate Time

Design the circuit so that fluctuation in the operate time does not result in problems.

For AC-operated Relays, the operate time fluctuates according to the supplied phase of the coil input voltage. The fluctuation is approximately half a cycle (10 ms) for small Relays and approximately one cycle (20 ms) for large Relays.

3.-(2)-16 Using AC-operated Relays
3) Coil Voltage Waveform

The voltage applied to the coil for an AC-operated Relay must form a sine wave. Power from commercial power supplies cannot be applied directly without any problem. If an inverter power supply is used, however, waveform distortion in the equipment may cause humming or abnormal coil heating.

AC coils are formed with shading coils to stop humming. Shading coils are used so that the sine wave does not cause these problems.

3.-(2)-17 Using Latching Relays
1) Coil Polarity for DC-operated Latching Relays

Check the catalog for the terminal numbers and polarity of applied power to correctly connect the Relay. Applying voltage with reversed polarity to DC-operated Latching Relays may resulting malfunctions, set failure, or reset failure.

3.-(2)-18 Using Latching Relays
2) Drive Circuit

Energizing due to self-contact may prevent normal latching. Do not use Latching Relays in the following type of circuit.

Use the type of circuit shown in the following figure.

3.-(2)-19 Using Latching Relays
3) Applying Voltage Simultaneously to Set and Reset Coils

Do not apply voltage at the same time to the set and reset coils. Simultaneously applying voltage to the set and reset coils for an extended period may result in abnormal coil heating, fire, or incorrect operation.

3.-(2)-20 Using Latching Relays
4) DC Input Circuit Design

Reverse voltage of a Relay coil or solenoid may cause operation failure if other Relay coils or solenoids are connected in parallel to the set coil or reset coil. As a countermeasure, change the circuit or connect diodes as shown in the following figures.

Circuit Precautions

3.-(2)-21 Using Latching Relays
5) Degradation over Time of Latching Relay Holding Ability

If a Magnetic Latching Relay is used left set for an extended period, changes over time will degrade the magnetic force, and the reduction in holding ability may cause the set status to be released. This is also because of the properties of semi-hard magnetic material, and the rate of degradation over time depends on the ambient environment (e.g., temperature, humidity, vibration, and presence or absence of external magnetic fields). Perform maintenance at least once a year by resetting, applying the rated voltage again, and then setting. (Applicable models: G2RK, MYK, G2AK, and MKK.)

3.-(2)-22 Load Switching Frequency

The possible load switching frequency depends on the load type, voltage, and current. Be sure to check operation using the actual equipment. If the switching rate is too high, arc connection or shortcircuiting between contacts may render switching impossible.

3.-(2)-23 Phase Synchronization for AC Load Switching

Perform switching so that the phase is random during switching. Synchronizing the Relay drive timing phase and the load power supply phase may result in contact fusing, locking, or other contact failures.

The ratings in the catalog are for random switching.

(3)Mounting Design

3.-(3)-1 Lead Wire Diameters

Lead wire diameters are determined by the size of the load current. As a standard, use lead wires at least the size of the cross-sectional areas shown in the following table. If the lead wire is too thin, it may cause burning due to abnormal heating of the wire.

3.-(3)-2 When Sockets are Used

Check Relay and socket ratings, and use devices at the lower end of the ratings. Relay and socket rated values may vary, and using devices at the high end of the ratings can result in abnormal heating and burning at connections.

3.-(3)-3 Mounting Direction

Depending on the model, a particular mounting direction may be specified. Check this catalog and then mount the device in the correct direction.

3.-(3)-4 When Devices Such as Microcomputers are in Proximity

If a device that is susceptible to external noise, such as a microcomputer, is located nearby, take noise countermeasures into consideration when designing the pattern and circuits. If Relays are driven using a device such as a microcomputer, and a large current is switched by Relay contacts, noise generated by arcing can cause the microcomputer to malfunction.

3.-(3)-5 Mounting Latching Relays

Operate the Latching Relay so that the vibration and shock from other devices (e.g., Relays) on the same panel or board generated when setting or resetting do not exceed the catalog values. Exceeding the values may cause the set or reset state to be released.

Latching Relays are shipped in the reset status, but abnormal vibration or shock may cause them to change to the set status. Be sure to apply a reset signal before using the Latching Relay.

4.Operating and Storage Environments

4.-1 Operating, Storage, and Transport

During operation, storage, and transport, avoid direct sunlight and maintain room temperature, humidity, and pressure.

If Relays are used or stored for an extended period of time in an atmosphere of high temperature and humidity, oxidation and sulphurization films will form on contact surfaces, causing problems such as contact failure.

If the ambient temperature is suddenly changed in an atmosphere of high temperature and humidity, condensation will develop inside of the Relay. This condensation may cause insulation failure and deterioration of insulation due to tracking (an electric phenomenon) on the surface of the insulation material.
Also, in an atmosphere of high humidity, with load switching accompanied by a comparatively large arc discharge, a dark green corrosive product may be generated inside of the Relay. To prevent this, it is recommended that Relays be used in at low humidity.

If Relays are to be used after having been stored for an extended period, first inspect the power transmission before use. Even if Relays are stored without being used at all, contact instability and obstruction may occur due to factors such as chemical changes to contact surfaces, and terminal soldering characteristics may be degraded.

4.-2 Operating Atmosphere

Do not use Relays in an atmosphere containing flammable or explosive gas. Arcs and heating resulting from Relay switching may cause fire or explosion.

Do not use Relays in an atmosphere containing dust. The dust will get inside the Relays and cause contact failure. If use in this type of atmosphere is unavoidable, consider using a Plastic Sealed Relay or a Metal Hermetically Sealed Relay.

4.-3 Using Relays in an Atmosphere Containing Corrosive Gas (Silicon, Sulfuric, or Organic Gas)

Do not use Relays in a location where silicon gas, sulfuric gas (SO₂ or H₂S), or organic gas is present.

If Relays are stored or used for an extended period of time in an atmosphere of sulfuric gas or organic gas, contact surfaces may become corroded and cause contact instability and obstruction, and terminal soldering characteristics may be degraded.

Also, if Relays are stored or used for an extended period of time in an atmosphere of silicon gas, a silicon film will form on contact surfaces, causing contact failure.

The effects of corrosive gas can be reduced by the processing shown in the following table.

4.-4 Adhesion of Water, Chemicals, Solvent, and Oil

Do not use or store Relays in an atmosphere exposed to water, chemicals, solvent, or oil. If Relays are exposed to water or chemicals, it can cause rusting, corrosion, resin deterioration, and burning due to tracking. Also, if they are exposed to solvents such as thinner or gasoline, it can erase markings and cause components to deteriorate.

If oil adheres to the transparent case (polycarbonate), it can cause the case to cloud up or crack.

4.-5 Vibration and Shock

Do not allow Relays to be subjected to vibration or shock that exceeds the rated values.

If abnormal vibration or shock is received, it will not only cause malfunctioning but faulty operation due to deformation of components in Relays, damage, etc. Mount Relays in locations and using methods that will not let them be affected by devices (such as motors) that generate vibration so that Relays are not subjected to abnormal vibration.

4.-6 External Magnetic Fields

Do not use Relays in a location where an external magnetic field of 800 A/m or greater is present. If they are used in a location with a strong magnetic field, it will cause malfunctioning.

Also, strong magnetic field may cause the arc discharge between contacts during switching to be bent or may cause tracking or insulation failure.

4.-7 External Loads

Do not use or store Relays in such a way that they are subjected to external loads. The original performance capabilities of the Relays cannot be maintained if they are subjected to an external load.

4.-8 Adhesion of Magnetic Dust

Do not use Relays in an atmosphere containing a large amount of magnetic dust. Relay performance cannot be maintained if magnetic dust adheres to the case.

5.Relay Mounting Operations

(1)Plug-in Relays

5.-(1)-1 Panel-mounting Sockets

1.Socket Mounting Screws
When mounting a panel-mounting socket to the mounting holes, make sure that the screws are tightened securely. If there is any looseness in the socket mounting screws, vibration and shock can cause the socket, Relays, and lead wire to detach.
Panel-mounting sockets that can be snapped on to a 35-mm DIN Track are also available.

2.Lead Wire Screw Connections
Tighten lead wire screws to the following torque.

1)M3 screw socket: 0.78 to 1.18 Nm

2)M3.5 screw socket:0.78 to 1.18 Nm

3)M4 screw socket: 0.98 to 1.37 Nm

The values are recommended when crimp terminals are used. If the screws connecting a panel-mounting socket are not sufficiently tightened, the lead wire can become detached and abnormal heating or fire can be caused by the contact failure. Conversely, excessive tightening can strip the threads

3.Use a mounting bracket to maintain a secure connection between the Relay and the socket. Abnormal vibration or shock may cause the Relay to become disconnected from the socket.

5.-(1)-2 Relay Removal Direction

Insert and remove Relays from the socket perpendicular to the socket surface.

If they are inserted or removed at an angle, Relay terminals may be bent and may not make proper contact with the socket.

5.-(1)-3 Back-connecting Sockets

Follow the procedure below for correct mounting.

The PY/PT Back-connecting Socket can be snap-mounted on a panel. The recommended panel thickness is 1 to 2 mm.

1.Insert the Socket into the cutout mounting hole on the panel from the wiring side.

2.Push the straps of the mounting bracket on the Socket with a flatblade screwdriver until all the tabs emerge from the other side (back) of the mounting panel.

3.When all four tabs come out from the other side (back) of the panel, the connecting Socket is fixed to the panel.

4.To remove the connecting Socket from the mounting panel, lightly push the Socket from behind (wiring side) while holding down each tab in turn with a screwdriver.

Using an inappropriate mounting panel thickness or incorrect mounting method may make it impossible to mount the socket or cause the socket to become disconnected.

5.-(1)-4 Wiring to Sockets for Wirewrap Terminals

Refer to the table at the right for correct mounting. Inappropriate wiring procedure may cause lead wires to become disconnected.

Note:A 0.65-dia. wire can be wound around the PY[]QN six times, while a 0.8-dia. wire can be wound around the PT[]QN four times.

5.-(1)-5 Terminal Soldering

Solder General-purpose Relays manually following the precautions described below.

1.Smooth the tip of the solder gun and then begin the soldering.

Solder: JIS Z3282, H60A or H63A (containing rosin-based flux)

Soldering iron: Rated at 30 to 60 W

Tip temperature: 280 to 300°C

Lead-free solder: 310 to 330°C

Soldering time: Approx. 3 s max.

2.Use a non-corrosive rosin-based