Systems & Electronics

DIA4L – Interface protection relay for active consumers
(according to CEI 0-16 2019-04 Norm)

The protection relay DIA4L belongs to SIGMA-L digital protection line and it performs three phase overvoltage and undervoltage protection, over frequency and underfrequency protection, residual overvoltage protection; it could be used as interface protection for active Users connected to MV electric power system.

DIA4L protection relay is compliant with Italian document Norma CEI 0-16 (2019-04) in reference to “interface protections”. The user can choose one or more of the functions listed in the following table:

Overvoltage protection 59
Undervoltage protection 27
Residual overvoltage protection 59N – 59Vo
Overfrequency protection 81>
Underfrequency protection 81>
Frequency thresholds with voltmetric control 81V
Positive sequence undervoltage protection (“) 27V1
Negative sequence overvoltage protection (‘) 59V2

(*) These thresholds are used by frequency thresholds with voltmetric control (81V)

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 – DIA4L manages the following thresholds:

  • 2 overvoltage thresholds
  • 2 undervoltage thresholds
  • 1 + 1 residual overvoltage threshold
  • 2 overfrequency thresholds
  • 2 underfrequency thresholds
  • Frequency thresholds with voltmetric control
  • 1 positive sequence undervoltage threshold
  • 1 negative sequence overvoltage threshold
  • remote trip
  • breaker failure

All thresholds have definite-time delay.

Trip condition is shown and recorded with LEDs and with a message on the display.