Compensation of simple fiber optic Faraday effect sensors

摘要

A monitoring system for detecting earth faults in an electrical power supply grid providing a power signal includes a plurality of monitoring devices, each of the monitoring devices including a detector for detecting the level of harmonics in the power signal, wherein the level of harmonics is detected in a specific frequency range. Each of the monitoring devices further includes a memory for storing a harmonics reference value, a processor for comparing the detected level of harmonics with the reference level, and a communication device for transmitting an alarm if the detected level of harmonics is above the reference level for a specific period of time. Each of the detectors includes an optical sensor for detecting the harmonics by use of the Faraday effect.

主权项

1. A method of communicating between a master unit and a plurality of monitoring units monitoring an electrical power supply grid, said master unit comprising a communication unit connected to a wired or wireless network for communicating with said plurality of monitoring units, each of said monitoring units comprising a transmitter and receiver having a wired or wireless connection to said network for transmitting and receiving data messages to and from said master unit, each of said monitoring units comprising a memory unit configured for storing one message, said method comprising:
transmitting a message from said master unit to at least one of said monitoring units; receiving said message by said at least one of said monitoring units; and if said memory unit of said at least one of said monitoring units is empty, storing said received message in said memory unit, and if said memory unit already contains a previously-received other message, discarding said received message.