H Troubleshooting
The following table can be used for troubleshooting when Relay
operation is not normal. Refer to this table when checking the circuit
and other items. If checking the circuit reveals no abnormality, and it
appears that the fault is caused by a Relay, contact your OMRON
representative. (Do not disassemble the Relay. Doing so will make it
impossible to identify the cause of the problem.)
A Relay is composed of various mechanical parts, including a coil,
contacts, and iron core. Among these, problems occur most often
with the contacts, and next often with the coil.
These problems, however, mostly occur as a result of external factors
such as methods and conditions of operation, and can generally be
prevented by means of careful consideration before operation and by
selecting the correct Relays.
The following table shows the main faults that may occur, their
probable causes, and suggested countermeasures to correct them.
Fault Probable cause Countermeasures
(1) Operation fault 1. Incorrect coil rated voltage selected
2. Faulty wiring
3. Input signal not received
4. Power supply voltage drop
5. Circuit voltage drop (Be careful in particular of high-
current devices operated nearby or wired at a
distance.)
6. Rise in operating voltage along with rise in ambient
operating temperature (especially for DC)
7. Coil disconnection
1. Select the correct rated voltage.
2. Check the voltage between coil terminals.
3. Check the voltage between coil terminals.
4. Check the power supply voltage.
5. Check the circuit voltage.
6. Test individual Relay operation.
7.
• For coil burning, see fault (3).
• For disconnection due to electrical corrosion,
check the polarity being applied to the coil voltage.
(2) Release fault 1. Input signal OFF fault
2. Voltage is applied to the coil by a sneak current
3. Residual voltage by a combination circuit such as a
semiconductor circuit
4. Release delay due to parallel connection of coil and
capacitor
5. Contact welding
1. Check the voltage between coil terminals.
2. Check the voltage between coil terminals.
3. Check the voltage between coil terminals.
4. Check the voltage between coil terminals.
5. For contact welding, see fault (4).
(3) Coil burning 1. Unsuitable voltage applied to coil
2. Incorrect rated voltage selected
3. Short-circuit between coil layers
1. Check the voltage between coil terminals.
2. Select the correct rated voltage.
3. Recheck the operating atmosphere.
(4) Contact welding 1. Excessive device load connected (insufficient
contact capacity)
2. Excessive switching frequency
3. Short-circuiting of load circuit
4. Abnormal contact switching due to humming
5. Expected service life of contacts reached
1. Check the load capacity.
2. Check the number of switches.
3. Check the load circuits.
4. For humming, see fault (7).
5. Check the contact ratings.
(5) Contact failure 1. Oxidation of contact surfaces
2. Contact abrasion and aging
3. Terminal and contact displacement due to faulty
handling
1.
• Recheck the operating atmosphere.
• Select the correct Relay.
2. The expected service life of the contacts has been
reached.
3. Be careful of vibration, shock, and soldering
operations.
(6) Abnormal contact
consumption
1. Unsuitable Relay selection
2. Insufficient consideration of device load (especially
motor, solenoid, and lamp loads)
3. No contact protection circuit
4. Insufficient withstand voltage between adjacent
contacts
1. Select the correct Relay.
2. Select the correct devices.
3. Add a circuit such as a spark quenching circuit.
4. Select the correct Relay.
(7) Humming 1. Insufficient voltage applied to coil
2. Excessive power supply ripple (DC)
3. Incorrect coil rated voltage selected
4. Slow rise in input voltage
5. Abrasion in iron core
6. Foreign material between moveable iron piece and
iron core
1. Check the voltage between coil terminals.
2. Check the ripple percentage.
3. Select the correct rated voltage.
4. Make supplemental changes to circuit.
5. The expected service life has been reached.
6. Remove the foreign material.
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C-15
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