The ESM 3 is used to monitor the electric potentials between different earth-systems of DC rails. This is required because during the operation of DC railroads with return conductor via the running rail electric potential can occur which can be dangerous to persons and buildings. The reason for this phenomenon are the different grounding resistances.
The device monitors the potentials of the connected earth systems and switches when thresholds are reached.
For messages / alerts two potential free changeover contacts are available. Data are send to an operations center via modem. In the operations center and evaluation software is implemented.
The device is installed at the selected location and captures every 0,5 s the difference in the earth potential. If the measured value exceeds a pre-defined threshold an event counter is incremented. The ESM 3 can be reset via a remote control connection or via a push-button on the device. In addition the function can be reset via the modem interface.
If – during an adjustable observation period (1 …99 min) – the maximum number of counts is exceeded (also adjustable between 1 … 99) the communication gate is set to “error” and an alarm counter is incremented. If the maximum count is not exceeded during the observation period an automatic reset is performed.
You will find additional information in the datasheet: