PQD4L – Digital directional power and over and under active and reactive power protection relay
The protection relay PQD4L belongs to SIGMA-L digital protection line and it performs functions as directional power and over and under active and reactive power protection relay. The user can select the insertion mode and the protection functions in compliance to the table below:
| PROTECTION FUNCION AND INSERTION |
| 67 – Y (directional overcurrent or directional power) |
| 67 – D (directional overcurrent or directional power) |
| 32PQ – 37PQ – 1Y (over and under power) |
|
32PQ – 37PQ – D (over and under power) |
| 32PQ – 37PQ – 2Y (over and under power) |
| 32PQ – 37PQ – Aron (over and under power) |
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 – PQD4L manages the following thresholds:
- 3 directional overcurrent and/or energy thresholds (ANSI 67)
- 2 active overpower thresholds (ANSI 32P)
- 2 reactive overpower thresholds (ANSI 32Q)
- 2 active underpower thresholds (ANSI 37P)
- 2 reactive underpower thresholds (ANSI 37Q)
The threshold 67.S1 can be programmed either definite time or dependent time in compliance with IEC 60255-151 specifications; all 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.
