The protection block of RPD-250 is designed to prevent failure of the consumer by limiting impulse network noise and then disconnecting the consumer in cases of reduced power quality.
The consumer is connected by an electromechanical relay Fig. 1 after evaluating the characteristics of the mains voltage and evaluating its suitability.
Disconnection occurs at increased mains voltage, contactors chatter, as well as impulse noise arising from lightning discharges and during transients in the network. After the normalization of the electrical network parameters, it is turned on again.
It is used to protect devices integrated in the network TN-C. Voltage limitation occurs between the “line” and “neutral” conductors; therefore, application in networks with a different type of grounding requires additional measures to limit impulse noise and increased voltage between the line-to-ground and neutral-to-ground conductors.
For long-term operation of RPD-250 and reliable consumer protection it is recommended:
– for the TN-C network (as shown in Fig. 2) install a fuse FU1 rated for the maximum allowable current RPD-250 at a rated voltage of the fuse 1kV or higher, also install a nonlinear voltage limiter R1 with an upper limit of 2kV;
– for the TN-S network (as shown in Fig. 2), install fuses FU1 and FU2 designed for the maximum allowed current of the RPD-250 at the rated voltage of the fuse 1kV. Also install non-linear voltage limiters R1 with an upper limit of 2kV, and R2 and R3 with an acceptable voltage for stable operation of the consumer under the influence of line-to-ground and neutral-to-ground, usually the upper limit of 1250V.
The protection device RPD-250 should be installed at a distance of no more than 100 meters from the consumer.