The Rotor Earth Fault Detector is designed to pick up fault currents between the rotor field winding and earth in synchronous machines using infra-red communication.
Due to an increasing demand in rotor diagnostics and telemetry, PPI have designed a low cost, robust solution for detecting rotor earth faults between the rotor and field of synchronous machines.
The devices uses a robust, epoxy moulded Transmitter Unit, mounted onto the rotor shaft at the diode bridge, where it receives its power from the field voltage and continuously measures for any leakage currents between field and earth.
During this stage, a signal is sent to the PT Unit (mounted on the end-frame) to indicate sufficient rotor voltage and healthy operation. During a failure in the rotor insulation, a modulated signal is sent to the frame mounted PT Unit and an alarm is activated on the Receiver Unit.
PT Unit and Receiver
The Receiver Unit can be mounted anywhere on the machine or inside a control panel. Three outputs are available to indicate Receiver Unit power, Transmitter Unit power and a Rotor Earth Fault Alarm.
The REF Detector is designed for IP66 and can operate in Zone 1 and Zone 2 hazardous areas. An enhanced version is currently being developed to transmit larger quantities of data and parameters, such as current, voltage and temperature.