Electrical cabinets for overhead cranes

The electrical control cabinet

Each overhead crane needs controls to manage its movements. These are set up and wired in a rectangular cabinet made using thick sheet steel, with a door on the front side.

The paint covering it is a RAL 5009 epoxy paint. On the sides multi-pin connectors are installed, which means that it is possible to connect and disconnect various festoon cables or travelling motor power cables, as well as various limit switches and sensors without having to open the cabinet door.

Each of the connectors has its own cable and each different connector model corresponds to its cable only, so it is impossible to make a wrong connection.

The composition and wiring of the electrical cabinet

First there is a main rotating isolator switch equipped with an external handle on the front of the cabinet, enabling electrical power isolation of the installation, then a general On/Off switch controlled directly by the hanging control box with the On/Off/Horn button.

This is for putting the crane into resting position when not in use and returning it to use with a horn to signal this. The protective circuit breakers counter short circuits and power surges in the motor, control transformer etc...

The control transformer transforms 400 volts three-phase voltage to 48 volts single phase voltage for the control circuit. In the case of engines subject to frequency change, three SCHNEIDER converters are installed, one for the hoist motor and its brake, one for the steering motor and the last for the travelling motors.

In cases where the motors are operated without using this technology, the overhead crane electrical cabinet will be fitted with reversing switches.

Electrical cabinet quality

As with all parts manufactured by OMIS, it of the highest level. Each lead wire has a marker corresponding to the electrical wiring diagram. The marks are made directly on the wire insulation. Looking at the different connection terminals for converters, contactors, terminal blocks, it is very easy to see this mark.

The lead wires from different cables coming from the outside, such as festoon cables and motor cables, are subject to the same obligations.

Each electrical cabinet manufactured by OMIS is tested on an appropriate test bench before shipping to avoid electrical wiring errors.