Motor and thermal protection issues
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Why did both the motor and the thermal protection device get damaged? The protection setting was also below the motor’s rated current, yet I often change the wires to make the motor rotate in the opposite direction. Everyone, please analyze what the specific reasons are for both burning.
Does the front pole have appropriate short-circuit protection? Generally, thermal relays only provide thermal protection, but they cannot break the circuit in the event of a short circuit
Reversing should not be a problem; check whether there is a phase loss while the motor is running, and whether the thermal protection system has phase loss protection functionality.
It’s completely normal. Thermal protection isn’t foolproof; when the current is too high, heat builds up and the protection mechanism gets disabled. I’ve encountered a situation where the thermal protection didn’t function, causing the circuit breaker to trip repeatedly – it just takes some time to figure out what’s going on
It might be a failure of the thermal protection, which caused the motor to burn out as well.
1: Check whether the thermal protection has failed (thermal relays and circuit breakers have overload protection functions, and it’s very unlikely that both will fail at the same time). I’m not sure what type of thermal protection is used by the original poster 2: Is a fuse installed in the power circuit of the motor? 3: Does frequent wire changes lead to loosening at the wiring terminals, thereby causing the motor to operate with a missing phase? OP, frequent forward and reverse rotation of the motor should not be achieved by frequently changing the wires. This can be achieved through two AC contactors, with interlocking in terms of programming and electrical connections. It won’t cost much either. Operating the motor has also become much easier.
It’s likely due to the lack of a fuse; there’s a short circuit, and the thermal protection mechanism cannot be activated