Intermediate relay common fault handling method - Database & Sql Blog Articles

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The intermediate relay is one of the control relays. Generally used as an auxiliary use, that is, when the control circuit requires a large number of contacts and a large capacity, the number of control loops or signal amplification can be increased by the intermediate relay. During operation, when the voltage of the coil reaches the specified value, the intermediate relay operates.
Since the structure of the intermediate relay is basically the same as that of the contactor, the common faults, diagnosis and countermeasures of the contact part and the electromagnetic system can be referred to the relevant part of the contactor. It is only necessary to point out that the contacts of the intermediate relay are prone to false connection faults. This fault often occurs during the operation of the electrical control. It does not necessarily occur frequently or fixedly, so it is difficult to capture, making the fault difficult to judge. But when it happens occasionally, it can cause a major accident. The reason for this failure is that the actual voltage across the coil of the electromagnetic device is lower than 85% of the rated voltage due to the change in the contact resistance of the control circuit, so that the core cannot be attracted, causing the circuit to lose control.
The best way to eliminate the failure is:
(1) Try to avoid using a low voltage of 12V or less as the control voltage, because in this low-voltage circuit, the contact virtual connection failure is most likely to occur.
(2) When the control circuit adopts 24V as the control voltage, parallel type contacts should be used to improve the operational reliability.
(3) When the control circuit must be controlled with low voltage, it is better to use 48V.
(4) It is better to use 110V and above voltage as the rated control voltage for the control loop, which can effectively prevent the virtual connection of the contact.