Selection Guide for Substation Alarm Units (Event Recorders)
The alarm unit is the heart of substation warning systems, recording events with millisecond precision. Learn the right selection criteria in this guide.
What Is an Alarm Unit?
An alarm unit (event recorder) monitors dozens to hundreds of points in a substation — breaker trips, relay faults, sectionalizer and disconnect status — issuing audible and visual warnings and timestamping every event.
Why Millisecond Event Recording Matters
During a network fault, several relays and breakers operate within fractions of a second. Correct Sequence-of-Events analysis is only possible with millisecond-resolution timestamps — the key feature distinguishing a true event recorder from a simple annunciator.
Selection Criteria
- Number of input channels (from 20 up to 160)
- Event recording resolution of at least 1 ms
- Color LED display with configurable channel labels
- Ethernet and serial connectivity with industrial protocols
- Network monitoring software with event archiving
Rizmooj Products
Rizmooj Electric Toos manufactures a full family of alarm units, including the AMA500 (160 channels), the AMA520 (20 inputs), and the smart AMA524, all in service across the country.