The DC circuit circuit breaker has tripped; please help analyze it
Thread Content
A 4A circuit breaker supplies power to the coils of 32 relays; these 32 relays are input relays that receive feedback from electric valves. There is a 24V positive terminal on the cabinet side, while the 24V negative terminal goes to the site. When the electric valve is operated during the process, the circuit breaker trips, yet the coils of the relays are functioning normally. Why is that? Later, pushing it onto the air switch fixed it. What exactly is causing it? Could there be a problem with the feedback from the electric valve?
Instant overload – recalculate circuit breaker capacity
The wire for controlling the electric valve shares the same cable as the feedback wire of the valve; the cable is damaged. The circuit for controlling the electric valve contains 24V DC power from the valve itself, while the feedback circuit of the valve has 24V DC power from the DCS. When the valve is switched on or off, these two power supplies are connected to each other, which causes the circuit breaker to trip
When starting the electric valve in the process, the high starting current causes the circuit breaker to trip; therefore, a circuit breaker with a higher capacity is selected after recalculation, in order to accommodate the total current of all operating electric valves plus their starting currents.
Calculate the maximum current in the 24V circuit based on the on-site solenoid valve, and select a circuit breaker with an appropriate capacity.
It is usually an instantaneous overload, which may be caused by poor contact or an internal short circuit; the elementary embryo is not easy to find. Of course, over time, the components connected to the circuit breakers will age, which may also lead to instability
The main question is: shouldn’t the feedback from the electric valve not require power from the DCS? How is there a 24V output?