Witt Solutions GmbH
The WITT WB-CM 3 Monitors the Insulation of Power Cables Such as Return Conductors or Supply Lines
This article first appeared in the Railway-News magazine Issue 3 2023.
The monitoring of cable systems in DC installations for damage is important for the early prevention of fault currents that can damage buildings and become dangerous to people, and is required by various standards.
The WITT WB-CM 3 monitors the insulation of power cables such as return conductors or supply lines.
Typical areas of application:
- Light rail (underground, tram etc.)
- Charging stations of trains, buses, trucks
- Battery buffer systems
- Solar power systems
- Wind turbines
Description
The device is used for insulation monitoring of cable systems in DC installations. The insulation measurement is carried out between the insulating outer sheath and a reference earth. Different threshold values can be set for each measurement. Signalling is by means of optional potential-free signalling contacts or via a communication protocol. Operating status is indicated by LED. Operation is by means of a pushbutton. Parameters can be set at the factory or using the WTC service case and the communication protocol.
The unit is built into a top-hat rail-mountable plastic housing.
Function
Simple monitoring of the critical cable infrastructure.
To measure the cable insulation, the shield and the reference earth are connected to the WB-CM3. The WB-CM 3 determines the measurement data and evaluates them according to the stored threshold values. Up to three threshold values expressed in terms of parameters can be set for the measuring point. The message of exceeding the threshold value can be fed into the system control via a communication protocol and or a message contact extension. A time delay can be parameterised between exceeding the threshold value and triggering the signalling contacts. The leakage current flowing to earth is very low at 2mA only.
The operating and switching status is indicated by a local LED. Operating states can be reset by means of a push-button.
