Testing relays can usually be done through the following methods:
1.One Appearance inspection: Appearance inspection mainly includes the following parts.
1. Shell inspection: Firstly, the shell of the relay should be checked for completeness, no cracks or deformations. The shell should present a uniform and dense luster, without obvious color difference or scratches
2. Pin inspection: Check the pins from the bottom of the relay, mainly to check whether the pins of the relay are straight, without bending or breaking. If the pins are bent or broken, please replace them in a timely manner. Next is whether there is copper slag or rust on the pins. A normal pin should be kept clean and tidy, as the presence of copper slag or rust on the pins can affect the use of the relay.
3. Packaging inspection: Check whether the packaging of the relay is intact and whether there are any damages or cracks on the surface. Secondly, check whether the seal of the relay is complete. Common relays in daily life may have several different types of casings, such as open type and dust cover type. Dust cover type casings have good sealing properties and can effectively prevent corrosive gases and dust from entering. If the relay is covered with a dust cover, it is necessary to carefully inspect the packaging of the relay.
4. Contact inspection: Pay special attention to whether the contacts are clean and free of debris, and whether there is oxidation phenomenon. Contact oxidation generally causes poor circuit contact, affecting the service life of relays, and may even cause short circuits in the circuit. Next, observe the appearance of the contact points and check for any signs of erosion, dents, etc
2.Measure resistance:
1. Coil resistance measurement:
Test the coil resistance of the relay. Normally, we use the ohm range of the multimeter. Why choose the ohm range for measurement? Because the resistance value of the internal coil of the relay should be relatively small. If the measured resistance value is small, then changing the relay coil resistance is not a problem. However, if the measurement result shows an infinite resistance value, it may indicate that the coil is open and the relay is damaged. It is necessary to replace the relay in a timely manner.
2. Contact resistance measurement:
When testing contact resistance, we need to know that contacts are mainly divided into two types: normally closed contacts and normally open contacts. Under normal conditions, the resistance value of normally closed contacts is generally below 1 ohm, and the resistance is close to 0. The resistance value of normally open contacts should be infinite. We distinguish the type of contact and measure the resistance values of these two types of contacts to determine whether the relay is working properly based on the above mentioned criteria.
3. Power on test:
Apply current to the coil inside the relay, apply rated voltage, listen carefully for any suction sound, and observe if the contacts move. At this time, the resistance of the normally open contact after being pulled in should be close to zero, and the resistance of the normally closed contact should be infinite.
4. Test the contact performance of the contact points:
Detect the contact resistance and voltage drop of the contacts by using a larger current to determine if the contact is good.
For example, a simple circuit can be composed of a light bulb and a power supply, and the light bulb can be controlled to turn on and off through a relay. Observing the brightness changes of the light bulb can determine the contact condition of the contacts.
5. Action time test:
In industry, we measure the action time of relays using oscilloscopes and signal generators. First, we connect the oscilloscope and signal generator to the relay to generate a control signal and observe the response of the relay. Oscilloscope can be used to record and display the time from receiving control signals to completing state switching of relays, thereby obtaining accurate measurement values of action time.
Opinion: In industrial automation control systems, high reliability is required for relays. Regular testing and maintenance of relays in critical areas can effectively reduce production downtime and equipment damage caused by relay failures.
I hope this information is helpful to you. If you encounter any specific problems during the testing process, please feel free to consult me at any time. If you have a demand for relay products, we can also provide you with relay solutions.Contact Us
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