GE P444 User Manual

P44x/EN CM/H
b6
Commissioning
(
CM) 9-28
MiCOM P40 Agile P442, P444
In the characteristic above, the parts marked A, B and C are intersections
between several zones.
• The surface A is considered as being in zone 1.
• The surface B is not a part of the characteristic (no start element).
• The surface C is not a part of the starting characteristic (up to version A4.0, a new
logic is implemented to keep Z1 forward detection in area C (even with a fault negative
reactance value higher than the reverse limit X4) )
Plausibility:
For a characteristic to be plausible, its various parameters must comply with the following
equations: (no blocking plausibility check is provided by the internal logic control of the relay)
• if zone P is set forward:
 Z1 < Z1ext < Z2 < Zp < Z3
 tZ1 < tZ2 < tZp < tZ3
 R1G ≤ R2G ≤ RpG ≤ R3G
 R1Ph ≤ R2Ph ≤ RpPh ≤ R3Ph
• if zone P is set reverse:
 Z1 < Z1ext < Z2 < Z3
 Zp < Z4
 tZ1 < tZ2 < tZ3
 tZp < tZ4
 R1G ≤ R2G ≤ R3G
 RpG ≤ R4G
 R1Ph ≤ R2Ph ≤ R3Ph
 RpPh ≤ R4Ph
• The Z minimum value measured by the relay is: 60 mohms (Z1min set in S1 is 1ohm
with CT 1Amp & 200 mohms with CT 5Amp)
• There is no limit for the R/X ratio because a floating-point processor is used for the R
calculation & X calculation (separated dynamic range for each calculation). In
consequence the limit will be given by the angle error of the CT.
For example in PUR with CT accuracy angle at 1° (for IN), this gives a R/X = 5,7 – to keep a
10% error in the X1 measurement.
• R limit: min. 0 /max. 80 ohms (CT 5Amp) – min. 0/max. 400 ohms (CT 1Amp)
• X limit: min. 0,2/max. 100 ohms (CT 5Amp) – min.1/max. 500 ohms (CT 1Amp)
To simulate a two-phase fault
The two-phase fault simulation principle is the same as the one used to simulate a single-
phase fault but:
• the voltage reference is the line to line voltage between phases, Uab for example;
• the reference current is the difference between the phase-currents, Ia - Ib for example;
 the fault impedance Z = (Uphase-phase/(Iphase1 - Iphase2)).
 the R1M point (single phase) is replaced by the R1ph point.(Biphase)
Two-phase characteristic with reverse zone P:

GE P444 Specifications

General

Brand	GE
Model	P444
Category	Protection Device
Language	English