Systems & Electronics

HAR1N – Frequency and overfluxing digital multifunction relay

The protection relay HAR1N belongs to the SIGMA-N digital protection line and one or more of the functions listed below are activable:




Over-frequency ANSI 81
Overfluxing ANSI 59/81
Max. frequency rate-of-change df/dt
Max. voltage vector shift ΔΘ

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

Application – the relay HAR1N is designed to protect generators operating in parallel with the grid or in island systems.

The relay manages the following thresholds:

  • under-frequency thresholds
  • over-frequency thresholds
  • overfluxing thresholds
  • max. frequency rate-of-change thresholds (module)
  • max. voltage vector shift thresholds

The first threshold of the overfluxing function (FL>) can be programmed as definite time or dependent time in

compliance with IEC 255-4 (ratio between the measured V/f and the related threshold FL>).

The remaining thresholds are definite time (the voltage vector shift thresholds operate instantaneously).

Each definite time delay can be combined with an additional timer controlled by the digital inputs. The trip of the relay is shown and memorized by LEDs and by a message on the display.

A programmable undervoltage threshold is provided to inhibit the functions of the relay during the generator start-up; the functions are also inhibited when the frequency exceeds the range 35÷75 Hz.