A Boltek EFM-100 Electric Field Monitor measures the static electric field generated by thunderclouds electric field in Volts per meter (measurement accuracy 5%). Lightning is detected as a sudden change in the static electric field.
EFM-100 can
• Log date, time and distance of nearby lightning.
• Monitor lightning up to 38 km away.
• Detect the high electric field conditions which precede lightning.
• Short-range detector is optimized for close lightning to provide the best distance accuracy while ignoring far away lightning.
• Monitor up to four separate locations per PC.
• Watch trends develop.
• Attention getting alarms.
• Review archived data from previous storms.
• Stay current with free software updates from the Boltek website.

It is mounted on a 7m on the roof of MAKET building on the Aragats Research Station, near to the weather station. During winter height reaching to 5m because of snow.
Data frequency is 1Hz.
Calibration of the field meter alongside was performed on August of 2010.

This is used in the Glocaem potential gradient network