Three phase Pump Protection Relay without level sensors- PF-R

Underload protection by cos φ

The great advantage of these relays is that, by using the motor itself as a sensor and without requiring any external detectors, they monitor the cos φ of the motor and stop it before a breakdown caused by dry running, cavitation or closed valve occurs.

  • Eliminates need for level sensors to detect dry running.
  • For 3-phase motors from 1 to 630 A and over. Cable feed through relay itself.
  • Precise motor heating and cooling memory, reproduces its thermal image.
  • Visual indication of tripping cause.
  • Adjustable reset time for cos φ.

Suitable for 3-phase submersible pumps, petrol station pumps, and other type of pumps and systems where running without load is critical (dry well, broken transmission belt, etc.).

External Display Module

By means of this plug-in optional accessory, the relay status can be seen and reset from the exterior of the electrical panel board.
Easy to install. Size of a Ø22 mm push button.
Suitable for motor control centres (MCC) and panel boards.
This optional display module is mounted externally, e.g. on the panel door or a draw-out unit in a motor control centre (MCC) and connected to the relay by a flat cable (length 2 meters).
The module has the appropriate LED’s to signal the trip cause and a reset push-button.
Weight: 0,05 kg.
Protection degree: IP50

PF 47-R

Without Level Sensors

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Protection functions:

  • Overload
  • Underload cos φ
  • Phase imbalance or phase loss
  • Phase sequence

“The PS and PF electronic relays have been specially designed to provide complete protection for both single and three phase pumps and any other system where dry running is a critical factor.”