Thermal Switch Failure

[drodriquez]

Has anyone seen repeated thermal switch failure in a motor application that doesn't produce much heat? I would expect heat to cause switch failure but this isn't the case.

[actionjack]

Thermal switches are electro-mechanical safety devices that open to stop current flow when the temperature at the device reaches a specific temperature.

Thermal switches are sometimes installed in the motor in order to protect the windings from damage during over-temperature events. The drive (or inverter) will use thermal switch signals to trip (shut down) if the motor overheats.

So if your thermal switch is opening and there is no excessive overheating in the motor, your problem may be as simple as the interconnecting wires. Check your connections between the drive and motor.

[drodriquez]

This is an old post now but the problem was just that, loose wires inside of a wire-nut which shouldn't have been there in the first place

[zigmund]

Loose wire nuts can wreak havoc, simply because they create confusion. they cause:

Poor Electrical Contact: A loose wire nut can cause poor electrical contact between wires, which can lead to voltage drops, overheating, and arcing. This can result in flickering lights, intermittent power loss, and damage to the circuit components.

Short Circuits: If a loose wire nut causes two or more wires to touch, it can create a short circuit, which can result in the circuit breaker tripping or the fuse blowing. This can also damage the circuit components and create a fire hazard.

Overheating: A loose wire nut can cause increased resistance in the circuit, which can generate heat and cause the wires and components to overheat. This can lead to melting of the insulation and wires, which can create a fire hazard.

Electrical Noise: A loose wire nut can cause electrical noise in the circuit, which can interfere with the performance of other electrical devices and equipment.

It is important to regularly check and tighten wire nuts in electrical circuits to ensure that they are secure and not causing any problems. If you suspect that a loose wire nut is causing issues, it is important to turn off the power to the circuit and fix the problem immediately to prevent any further damage or hazards.

If your equipment is moving or vibrating you probably shouldn't be using wire-nuts in the first place, a crimp on termination or connector would be more suitable.