Numerically stabilized low-impedance restricted earth-fault protection (LREFPNDF) - Arc protection - Merging unit - Transformer protection - 2 winding - Product Guide - RET615 Transformer Protection and Control - Relion 615 series - 5.0 FP1 IEC - IEC - 24.05.2023

RET615 Product Guide

Table 1. Numerically stabilized low-impedance restricted earth-fault protection (LREFPNDF)
Characteristic Value
Operation accuracy Depending on the frequency of the measured current: f n ±2 Hz
±2.5% of the set value or ±0.002 x I n
Start time

Minimum

Typical

Maximum

I Fault = 2.0 × set Operate value

37 ms

41 ms

45 ms

Reset time Typically 40 ms
Reset ratio Typically 0.96
Retardation time <35 ms
Operate time accuracy in definite time mode ±1.0% of the set value or ±20 ms
Suppression of harmonics DFT: -50 dB at f = n × f n, where n = 2, 3, 4, 5, …
1 Current before fault = 0.0, f n = 50 Hz, results based on statistical distribution of 1000 measurements
2 Includes the delay of the signal output contact