Systems & Electronics

IFD4L – Digital multifunction protection relay for M.V. lines

The multifunction protection relay IFD4L belongs to SIGMA-L digital protection line and it performs functions as phase overcurrent, earth fault (directional and not directional) and residual overvoltage relay.

IFD4L relay is compliant with Italian document Norma CEI 0-16 in reference to “general protections” and is equipped with internal Logger.

The user can select the insertion mode, the protection functions and auxiliary functions in compliance to the table below:

 

INSERTION AND FUNCTIONS ANSI

Two-phases overcurrent

50 51

Two-phases overcurrent + lo

50 51 50N 51N

Two-phases overcurrent + Uo

50 51 59N

Two-phases overcurrent + lo + Uo

50 51 50N 51N 67N 59N

Earth-fault overcurrent (non direct.) lo

50N 51N

Residual overvoltage (Uo)

59N
Earth-fault (lo + Uo) 50N 51N 67N 59N

2nd harmonic restraint

50BF

Cold Load Pickup

Breaker failure
Circuit breaker monitoring

 

All the functions of the relay are fully programmable by front panel keyboard or through a RS485 serial interface using a personal computer with set-up program; furthermore the relay can be programmed through a remote control and monitoring system.

Thresholds – IFD4L manages the following thresholds:

  • 3 phase overcurrent thresholds
  • 3 earth fault overcurrent thresholds
  • 3 directional earth fault thresholds
  • 2 residual overvoltage thresholds

The first threshold of each protection function can be programmed either definite time or dependent time in compliance with IEC 60255-151 specifications; other thresholds are definite time only. Each definite time threshold delay can be combined with an additional delay controlled by the digital inputs.

The trip of a threshold is shown by LEDs and with a specific message on the display.