In European electric hoists, the control circuit plays a crucial role in the control of lifting and lowering. The following is a detailed analysis of the control method of its control circuit during the lifting and lowering process:

1、 Overview of Main Circuit and Control Circuit

The electrical system of European electric hoists is usually divided into two parts: the main circuit and the control circuit. The main circuit is responsible for providing power to the electric motor, while the control circuit is responsible for controlling the motor's starting, stopping, lifting, and lowering actions.

2、 Control methods for lifting and lowering

1. Rising process

Button operation: When the operator presses the up button (such as SB1), the corresponding contactor coil (such as KM1) in the control circuit is powered on, the main contact is closed, and the power supply to the motor and electromagnetic brake is connected.

Electromagnetic brake release: After receiving power, the electromagnetic brake releases the brake shoe, allowing the motor to rotate forward and drive the hoist to rise.

Chain protection: During the rising process, in order to prevent misoperation from causing descent, the dynamic breaking contact of the rising contactor (such as the dynamic breaking auxiliary contact of KM1) will disconnect, cutting off the control circuit of the descending contactor to ensure that it cannot descend during the rising process.

2. Descent process

Button operation: When it is necessary to descend, the operator presses the descent button (such as SB2), and the corresponding contactor coil (such as KM2) in the control circuit is energized, and the main contact is closed.

Electromagnetic brake and motor action: After receiving power, the electromagnetic brake releases the brake shoe, and at the same time, the motor reverses, driving the hoist to descend.

Chain protection: Similar to the rising process, the control circuit of the rising contactor will also be cut off during descent to ensure that it cannot rise during descent.

3、 Security Protection and Control

Limit protection: European electric hoists are equipped with limit switches (such as SQ2, SQ3) during the up and down process. When the hoist reaches the upper and lower limit positions, the limit switches will cut off the main circuit to protect the equipment from damage.

Motor overcurrent and overheating protection: The motor is equipped with overcurrent and overheating protection devices inside. Once overcurrent or overheating occurs, the protection device will cut off the control circuit to protect the motor from damage.

Overload protection: Some European electric hoists are also equipped with overload limiters, which prevent overloading by measuring the load borne by the steel wire rope. Once overloaded, the limiter will issue an alarm signal and cut off the control circuit to ensure safety.

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