The Eight Electric Hoist Protective Devices

Electric hoist as lifting machinery, protection is an indispensable part,and today Jinrui Machinery will introduce the eight protections for you.

1, the main isolating switch
Wire rope electric hoist is provided in line at the main disconnect switch,to ensure the safety of maintenance man.
 

2, emergency switch

Emergency switch  should be installed on the driver reach the position to prepare for emergency situations, quickly power it down, and ensuring the safety of operator and equipment.
 

3, short circuit protection

Common short-circuit protection device including fuse protector & automatic air switch . It should be set at the main power for main power short circuit protection.
 

4, zero position protection

To prevent when the controller failed to be placed into the zero position, the driver start the vehicle suddenly and lead to accident, the crane each controller has a zero position protection.
 

5, loss of excitation protection

When there is no current in the DC motor , armature current surge caused the failure. 
 

6, overcurrent protection

AC motor stator loop DC motor armature circuit in series overcurrent relay. When the current exceeds the allowable value, the relay off the motor, protect the motor.
 

7, interlock protection

On the crane cab doors, access doors, each door hatch up or escalator mouth, set the trip switch, when the limit switch is opened, automatically cut off the power supply, the entire crane can not be started, in order to protect the safety of peopel.
 

8, ground protection

To prevent the metal frame crane personnel are charged when an electrical shock. Grounding cable to use that the cross-section is not less than 150mm2 of  flat steel or 10mm2 of copper wire, then it is connected by welding.