F&F PF-421 TRMS, Manual

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PF-421 TRMS

Automatic phase switch with 

the adjustable lower and upper 

voltage threshold

The PF-421 automatic phase switch is used to maintain the con-

tinuity of the power supply of a single-phase receiver in case of 

phase failure or when the phase exceeds preset parameters. The 

compact size of the device allows you to save space in the elec-

trical cabinet.

By measuring the RMS value of the voltage (True RMS), 

the switch guarantees the correct operation even when 

operating with a severely disturbed power supply net-

work.

A three-phase voltage (3×230 V+N) is connected to the input ter-

minals of the device. A single-phase voltage (230 V) of one of the 

phases appears at the output of the relay. The electronic circuit 

of the switch controls the voltage values of the supplied phases 

so that the output voltage is not lower or higher than the set 

Purpose

Functioning

F&F Filipowski sp. j.

Konstantynowska 79/81, 95-200 Pabianice, POLAND

phone/fax (+48 42) 215 23 83 / (+48 42) 227 09 71

www.fif.com.pl; e-mail: biuro@fif.com.pl

Do not dispose of this device in the trash along with other waste! 

According to the Law on Waste, electro coming from households free of charge and can 

give any amount to up to that end point of collec� on, as well as to store the occasion of 

the purchase of new equipment (in accordance with the principle of old-for-new, regar-

dless of brand). Electro thrown in the trash or abandoned in nature, pose a threat to the 

environment and human health.