The Surge Arresstor Monitoring Devise SAM measures the status of a surge arrestor and reports a broken one.

Surge arrestors are employed in a number of areas in railway operation to keep dangerous excess voltages away from persons and infrastructure. Dangerous excess voltages can develop by lightning strikes but also by switching activities in connection with inductivities, e.g. lines.

It is important that surge arrestors are not blown and cause for example a permanent short circuit. Even if no permanent short circuit is present it is advantageous to monitor the status and triggering of the surge arrestor.

SAM recognises the status of the surge arrestor in two independent ways:

  • The current flowing through the surge arrestor is reactionless measured.
  • The voltage which is present during the operation at the surge arrestor. This voltage has to vary over time otherwise the surge arrestor is shot circuited.

Both sensors operate independent of each other and lead to a message in case the surge arrestor has acted or it is overloaded or defect.

SAM can be equipped with a lithium-ion battery if no auxiliary power supply is available at the location. This battery can operate between 5 and 8 years.

A range of alternatives is available to pass on the messages:

  • GSM modem
  • Switching contacts
  • Bus system Ethernet

All parts of SAM are in one device. For the installation close to the tracks or close to buildings this is a waterproof plastic housing. In switching locations (indoors) SAM can also be executed as a cap rail module to be mounted in a 35mm cap rail.

For further information please download the datasheet: