Regarding the hazards and protective devices of phase line breakage in electric hoists, the following is a detailed analysis:

1、 The hazards of phase line breakage

In an electric hoist, a broken phase wire (i.e. one phase of the power cord) may cause the following hazards:

Equipment shutdown: A broken phase line will directly cause the electric hoist to lose some or all of its power supply, thereby stopping work and affecting production efficiency and progress.

Motor damage: If the motor continues to operate after the phase line breaks (such as through other phase lines or backup power supply), it may be damaged due to unbalanced current and voltage, and in severe cases, it may even burn out the motor.

Safety hazards: Phase line breakage may also lead to electrical fires, electric shocks, and other safety accidents, posing a threat to operators and the surrounding environment.

2、 Protective device

In order to reduce the harm caused by phase line breakage, electric hoists are usually equipped with the following protective devices:

Overcurrent protection device: When the motor current exceeds the rated value, the overcurrent protection device will quickly cut off the power supply to prevent the motor from being damaged due to overload. Although this is mainly to protect the motor from overload damage, it can also play a certain role when the phase line breaks and causes abnormal current.

Phase loss protection device: specifically used to detect whether the motor is in a phase loss operation state. Once a phase loss is detected, the protective device will immediately cut off the power supply to prevent the motor from continuing to operate in a phase loss state and being damaged. This is the most direct and effective way to prevent the harm of phase line breakage.

Thermal relay: Although thermal relays are mainly used for motor overload protection, they can also provide some protection when the motor overheats due to phase line breakage. By monitoring the temperature of the motor, the thermal relay can cut off the power supply when the motor overheats, preventing the motor from burning out.

Emergency stop switch: Although this is not a direct protective device for phase line breakage, the emergency stop switch allows operators to immediately cut off the power supply when abnormal situations are detected, thereby avoiding the escalation of accidents.

The main equipment produced by Hebei Makita: stage electric hoist, electric chian hoist, wire rope electric hoist，Hand chain hoist, lever hoist, pneumatic hoist and other lifting equipment