How to test auto relay?
Automatic relay is an important component in automation control system, widely used in industrial equipment, household appliances, automobile electronics and other fields. Its main function is to control large current through small current, thus realizing the automatic switching of circuits. However, due to long-term use or environmental factors, automatic relays may malfunction, resulting in equipment not working properly. Therefore, learning to test the status of automatic relays is a very practical skill for engineers and maintenance personnel.
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The role of the automatic relay and common faults
1. The role of automatic relay
Automatic relay is a kind of electromagnetic switch, which controls large current through small current and is widely used in automation control system. Its core function is:
Circuit isolation: to control large current through small current, to protect the control circuit from the impact of high current.
Automatic control: realizing automatic switching of circuits, widely used in automation equipment and systems.
Signal conversion: convert low-power signals to high-power signals, applicable to a variety of electronic equipment.
2. Common Failures
Coil failure: coil broken or short-circuit, resulting in the relay can not be absorbed.
Contact failure: contact oxidization, ablation or adhesion, resulting in the circuit can not be normal on and off.
Mechanical failure: spring failure or mechanical parts wear, resulting in the relay can not work properly.
Preparation of tools for testing automatic relays
Before testing the automatic relay, you need to prepare the following tools:
Digital multimeter: for measuring coil resistance and contact on-off.
DC power supply: used to simulate the control signal and test the relay suction and closure.
Screwdriver: for disassembling the relay or related parts.
Connecting wires and clips: for connecting circuits.
It is also important to understand the pin definitions of automatic relays. Usually, the pins of an automatic relay are labeled on the coil and contacts, for example, “COIL” means coil pin, “NO” means normally open contact, “NC” means normally closed contact, “COM” means normally closed contact, and “N” means normally closed contact. “COIL” indicates the coil pin, ‘NO’ indicates the normally open contact, ‘NC’ indicates the normally closed contact, and ‘COM’ indicates the common contact.
Steps for testing an automatic relay
1. Check coil resistance
Set the multimeter to resistance measurement (usually Ω), and touch the coil pins (usually “COIL” pins) of the relay with the meter pen. Under normal circumstances, the coil resistance value should be between tens of ohms to hundreds of ohms. If the resistance value is infinity, it means that the coil is disconnected; if the resistance value is zero, it means that the coil is short-circuited. Both conditions indicate that the relay is damaged.
2. Checking contact continuity
Normally closed contact (NC) test: Set the multimeter to resistance measurement, and use the pen to contact the “COM” and “NC” pins. When not energized, the resistance value of the normally closed contacts should be close to zero; after energized, the resistance value should be infinity.
Normally open contact (NO) test: use the meter to contact “COM” and “NO” pin. When not energized, the resistance value of the normally open contact should be infinite; after energized, the resistance value should be close to zero.
If the test result is not consistent with the above, it means that the contacts may be oxidized or damaged, and the relay needs to be replaced.
3. Test relay absorption
Connect the DC power supply to the coil pin (“COIL” pin) of the relay, and observe whether the relay is engaged or not (hear the “click” sound). If the relay does not engage, the coil or a mechanical part may be damaged. 4.
4. Check the operating voltage of the relay
Connect the DC power supply to the coil pins of the relay and gradually increase the voltage until the relay is engaged. At this time, the voltage value displayed by the multimeter is the operating voltage of the relay. If the difference between the operating voltage and the nominal value is large, it indicates that the relay is not performing well.
Precautions in testing
Safety first: Before testing the automatic relay, be sure to disconnect the power supply of the equipment to avoid electric shock or short circuit.
Correctly identify the pins: the definition of the pins of different models of automatic relays may be different, be sure to refer to the manual or logo of the relay.
Avoid short-circuiting: During testing, make sure that the connecting wires are properly connected to avoid short-circuiting and damaging the relay or other equipment.
Regular maintenance: Check the auto relays and their connecting wires regularly to ensure that they are in good condition.
Conclusion
With the above steps, you can easily test the status of the automatic relay and quickly determine whether it is working properly. As a key component in the automation control system, the performance of the automatic relay directly affects the operation effect of the equipment. Therefore, it is very necessary to check and maintain the auto relays regularly.
MobikeChip is always committed to providing customers with high quality electronic components and solutions. If you encounter any problems when testing or using auto relays, please feel free to contact us, we will be happy to provide you with technical support and service!
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