Earth Overcurrent Relay
NPIH800 provides the earth fault overcurrent protection for medium and high voltage electrical networks. This multi-function relay also supervises phase to earth short-circuits and the good operating of the circuit breaker and its trip circuits.
As well as the usual protection functions, NP800 relays provide monitoring, measurement and recording of the electrical quantities of the network.
The relays can be set locally, using either the keypad and display or the RS232 port, or remotely using the RS485 port. Setting, reading, measurement and recording are all available locally or remotely.
CONTROL AND PROTECTION FUNCTIONS
- Earth fault with 2 thresholds [51N] [50N]
- Latching of the output contacts 
- Trip circuit supervision of the breaker [74TC]
- BF Breaker failure [50N-BF]
- Configuration and parameter setting by local MMI or off-line / on-line PC
- Measurement of electrical quantities:
– Instantaneous, integrated and maximum values of earth currents
- Logical selectivity on the two earth thresholds
- 2 setting groups, locally or remotely selectable by digital input or by the communication channel
- Self-diagnosis: Memories, output relays, A/D converters, auxiliary supply, cycles of execution of software, hardware failure
- 3+1 assignable output units / 4 assignable digital inputs (option: additional board with 4 assignable output relays and 4 assignable digital inputs)
- Event recording: 250 locally recorded events, 200 saved in case of loss of auxiliary supply
- Disturbance recording according to Comtrade® format: storage of 4 recordings of 52 periods
- Optional Communication by Modbus® RS 485 or Ethernet by Modbus/TCP