WITT EPM 6 | ESM3 earth potential measurement device

Description

Application

The WITT EPM 6 is used to monitor voltages between earths in the vicinity of direct-current railways. When operating direct-current railways with a return path via the track, differences in earth resistance give rise to voltages that can be dangerous to people and structures. This measuring device monitors the potentials of the connected earths and switches off when the trigger values are reached.

Description

Two potential-free changeover contacts are available for signalling. Data is sent to a control centre via a modem. Server software is installed at the control centre.

Function

The device is installed at the measurement point and records the potential differences between the two earths every 0.5 s. If the magnitude of these differences exceeds a configurable threshold value, an event counter is incremented. The WITT EPM 6 can be reset via a telecontrol connection or using a push-button on the device. Furthermore, its function can be reset by sending a command to the modem interface. If, within a configurable monitoring period (1–99 minutes), the maximum permissible value of the event counter (also configurable from 1 to 99) is exceeded, the ‘Error’ signal output is activated and an alarm counter is incremented. Otherwise, the event counter is reset once the monitoring period has elapsed.