How to know if a relay is bad? Automotive Relays
Relays play a vital role in the operation of electronic equipment. Once a relay fails, it may cause the entire circuit system to not work properly. So, how to know if a relay is broken? Next, MobikeChip will introduce several ways to determine this in detail.
1. Appearance Inspection
Appearance inspection is the first step to determine whether the relay is damaged, simple and intuitive and can find many obvious problems. First of all, carefully observe the shell of the relay to see if there are signs of damage, deformation or scorching. A damaged case may expose the internal components, which are susceptible to dust, moisture and other influences that can lead to failure; deformation may imply that the relay has been subjected to external impacts and the internal structure may be damaged; and burn marks usually indicate that the relay has been overheated during operation, and that the internal components are likely to have been damaged.
Check the pins of the relay for bends, breaks or corrosion. Bent or broken pins will result in poor connection with the circuit and affect the normal operation of the relay; corrosion of the pins will increase the contact resistance and block the current transmission. If the pins are found to have these problems, it is necessary to further check whether the relay is also affected internally.
2. The sound and action judgment
Energize the relay and listen carefully for a clear “click” sound. Under normal circumstances, when the relay is energized, the internal electromagnetic mechanism will act to drive the contacts closed or open, thus making a “click” sound. If you don't hear this sound, the relay's solenoid coil may not be working properly, such as an open coil, short circuit, or insufficient power supply.
Observe the operation of the relay to see if the contacts are able to close and break properly. This can be determined by observing the state of the circuit connected to the relay. For example, if the relay is controlling a lamp, the lamp should light up (normally open contacts) or go out (normally closed contacts) when power is applied. If the state of the lamp does not change as expected, there may be a fault in the relay's contacts, such as sticky or poor contact.
3.Resistance Measurement
Using the resistance gear of the multimeter, you can measure the resistance of the key components of the relay, in order to determine whether the relay is damaged or not. Measure the resistance of the solenoid coil. The coil resistance value varies for different models of relays, but generally there is a standard range, which can be obtained by checking the product manual. If the measurement shows a resistance value of infinity, the coil may be open, i.e., the internal wires are broken; if the resistance value is much lower than the normal range, or even close to zero, the coil may be short-circuited. Either an open or a short circuit means that the relay's solenoid coil is damaged and is not functioning properly.
Measure the resistance of the contacts. When the relay is not energized, the resistance of the normally open contacts should be infinite and the resistance of the normally closed contacts should be close to zero. When energized, the resistance of the normally open contacts should be close to zero and the resistance of the normally closed contacts should become infinite. If the measurement results do not match the above, such as normally open contacts in the energized resistance is still very large, indicating poor contact; if the normally closed contacts in the energized resistance is not infinity, there may be contact adhesion problems.
4.The circuit function test
The relay will be installed in the actual circuit function test, which is an important method to determine whether the relay is damaged. Observe whether the part of the circuit controlled by the relay can work normally. For example, in the motor control circuit, the relay should be able to control the start, stop and forward and reverse of the motor. If the motor fails to operate as expected, after eliminating the motor itself, there is likely a problem with the relay.
During circuit operation, monitor the operating status of the relay for abnormalities such as overheating and firing. Overheating can be caused by excessive contact resistance within the relay, resulting in too much heat being generated as the current passes through, while firing can be caused by arcing of the contacts at the moment of closure or disconnection, both of which are indicative of a faulty relay that needs to be replaced or repaired in a timely manner.
At MobikeChip, we are committed to providing you with high quality electronic component products and professional technical support. Through the above methods, you can more accurately determine whether the relay is damaged or not. If you have any questions about the use of relays, testing or other electronic components, please feel free to visit MobikeChip website, our professional team will be happy to serve you.
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