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.
