How to inspect the electrical appliances of a crane

Electrical equipment is the more complex part of a crane. It operates under conditions of impact, vibration and swing, and is prone to malfunction. Especially in harsh environments such as high temperature, much dust and humidity, it is even more likely to malfunction and may cause accidents. Therefore, the main items for safety inspection of the electrical part of the crane are as follows:

1. Check whether the insulation resistance of the motor is within the normal range, and whether there is any abnormal noise and normal temperature rise during operation. When the machine stops, check whether the slip rings, brushes and wire joints have obvious cracks, wear, looseness and carbon powder adhesion, etc.

2. Check whether the collector and power supply sliding lines are deformed or worn, whether the tensioning device is normal, and whether the contact between the sliding line and the slider is good. Where power is transmitted by cables, it is also necessary to check whether the insulation layer of the cables is aged, whether the cable guiding device is flexible and whether the cables can be retracted and extended freely.

3. Inspect the electrical components and control system. Check whether the housings of each switch are damaged, whether the pressure at the contact points during closing is appropriate, and whether the capacity of the fuses meets the requirements. Check whether the main contacts and auxiliary contacts of the contactor are scorched, whether the pressure between the contacts is sufficient during contact, and whether the contacts are completely disengaged. Check if there are any attachments on the contact surfaces of the moving and stationary cores of the contactor, if there are any abnormal noises during contact, and if the arc extinguishing cover is intact. And whether each relay on the distribution cabinet is working properly, and whether each terminal post and wiring screw are tightened, etc. In the cab, it is necessary to check whether the action directions of each master controller are correctly connected. Pay attention to checking whether there is zero position protection. In particular, it is necessary to check whether there is an emergency power-off switch on the control console and confirm that the power can be effectively cut off in case of emergency. Similarly, it is necessary to pay attention to checking the sensitivity and reliability of the overload limiter, moment limiter, and each travel protection device.