The WITT EPM 6 is used for voltage monitoring between earths in the area of direct current railways. When operating direct current railways with return lines via running rails, different grounding resistances create voltages that can be dangerous for people and buildings. This measuring device monitors the potentials of the connected earths and switches when the response values are reached.
Two potential-free changeover contacts are available for messages. Data is sent to a control center via modem. Server software is installed in the control center.
The device is installed at the measuring location and records the potential differences between the two grounds every 0.5 s. If their amount exceeds a parameterizable threshold value, an event counter is incremented. The WITT EPM 6 can be reset via a telecontrol connection and a button on the device. In addition, its function can be reset by a command on the modem interface. If the maximum permissible level of the event counter (also adjustable from 1 … 99) is exceeded within an adjustable monitoring time (1 … 99 min), the message output “Error” is set and an alarm counter is incremented. Otherwise the event counter will be reset after the monitoring time has elapsed.