ELKO HRN-55 phase monitoring relay

Product description

ELKO HRN-55 is a voltage monitoring relay for three-phase networks (3 × 400 V, 50–60 Hz) with fixed monitoring limits. It monitors phase sequence, failure of any phase, and a voltage rise above 125% or drop below 75% of the nominal voltage. The relay is supplied from all phases, so it remains in operation even if one phase is missing.

Operation

The green LED is lit continuously to indicate the supply voltage. In the event of a phase failure or when the voltage exceeds the limits, the red LED flashes and the relay releases. When entering the fault state, a delay (0.1–10 s) adjustable with a potentiometer on the front panel is applied, which prevents short disturbances from tripping the relay. If the phase sequence is incorrect, the red LED is lit continuously and the relay remains open. If the supply voltage drops below 60% of the nominal value, the relay opens immediately without delay. The hysteresis is 2%.

Applications

The phase monitoring relay is used to protect three-phase equipment, such as motors and compressors, from phase faults and, if required, to control other functions. In emergency lighting systems, it can be used to ensure that the emergency lighting is activated if any phase fails; for example, according to the technical description of Panasonic MX emergency luminaires, the phase monitoring device is connected to a monitored input of I/O unit 4461/4462.

Installation

The relay is mounted on a DIN rail (EN 60715), and the mounting position is free. The enclosure is only 17.6 mm wide. The monitored phases L1, L2 and L3 also act as the supply terminals.