Regarding the protection of electric hoists against phase failure or misalignment, this is a key safety feature aimed at ensuring that electric hoists can safely stop running in the event of phase failure or misalignment in three-phase power systems, preventing possible equipment damage or safety accidents. The following is a detailed discussion on the phase failure protection of electric hoists:

1. The necessity of phase failure protection

Risk of phase mismatch: When the three-phase power supply of the electric hoist experiences phase mismatch, its movement direction may be opposite to the indicated direction, causing psychological pressure on the operator. At the same time, it may also lead to the failure of the safety protection devices set up by the crane (such as overload, height, travel, and lifting capacity limiters), increasing the risk of accidents.

Consequences of prolonged phase failure: Prolonged phase failure (loss) can lead to motor overheating, coil burning, and uncontrolled electric hoists may cause serious accidents such as heavy objects falling.

2. Working principle of phase failure protection

Normal state: During normal operation, only the power indicator light on the protector should be on, and all other indicator lights should not be on.

Slight imbalance: When the three-phase power supply is in a slight imbalance, the "wrong phase disconnection" indicator light may slightly light up, but it is a normal situation.

Fault status: If the motor cannot start and the "phase failure" indicator light is on after the protection device is connected to the control circuit, it needs to be dealt with. The usual handling method is to swap the positions of any two phases in the A, B, and C three-phase power supplies of the input protector, and then press the start button again. When the motor can start normally, the phase sequence of the protector is recognized. If the phase sequence changes in the future, the protector can play a protective role.

3. Setting and management of phase failure protection

Product standards and safety regulations: The setting of phase failure protection has been jointly recognized by product standards, safety regulations, and technical specifications, and should be given attention by design, production, renovation and maintenance units, as well as inspection and testing institutions.

Conforming to the principles of human machine engineering: From the perspective of design, manufacturing, and use, the installation of phase error and phase failure protection on electric hoists is in line with the principles of human machine engineering and also meets the requirements of intrinsic safety.

4. Overvoltage, undervoltage, and delay protection

The phase failure protection device with overvoltage, undervoltage, and delay protection settings should be set according to the requirements of the product manual for overvoltage value, undervoltage value, and protection action time during use. The specific methods and parameters for these settings may vary depending on the product.

5. Maintenance and Inspection

Regularly inspect and maintain the phase failure protection device of the electric hoist to ensure that it is in good working condition.

Inspection includes but is not limited to the brightness of indicator lights, the reliability of protective device operation, and the tightness of electrical connections.

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