GE P24DM User Manual

4.2 RESIDUAL COMPENSATION
To improve accuracy of impedance measuring elements such as those used in distance protection and fault
locators, the total loop impedance calculation Z
LP
/I
A
can be calibrated by the positive sequence impedance
between the relaying point and the fault (Z
F1
) using the following equation:
Z
V
I k I
F
A
A ZN N
1
=
+ ⋅
where:
● V
A
is the phase A voltage
● I
A
is the phase A current
● I
N
is the residual current, derived from the phase currents by the equation:
I I I I
N A B C
= + +
● k
ZN
is the residual compensation coefficient given by the complex equation:
k
Z Z
Z
ZN
L L
L
=
−
0 1
1
3
where:
● Z
L0
is the total zero sequence impedance of the line (a complex value)
● Z
L1
is the total positive sequence impedance of the protected line (a complex value)
The complex residual compensation coefficient is defined by two settings: kZN Res Comp (the absolute value) and
kZN Res Angle (the angle in degrees).
Caution:
The kZN Res Angle is different to that in LFZP, SHNB, and LFZR products: If importing
settings from these products, you must subtract angle ÐZ
L1
4.3 MUTUAL COMPENSATION
On parallel circuits, mutual flux coupling can alter the impedance seen by fault locators and distance zones. A
current input (the Mutual Compensation input) is provided to compensate.
If you want to use Mutual Compensation, the connection polarity must match that shown in the connection
diagram and the element must be Enabled in the settings.
Consider for example an A-phase to earth fault on one circuit of a parallel circuit. The positive sequence
impedance between the relaying point and the fault can be calculated using the following equation:
Z
V
I k I k I
F
A
A ZN N Zm M
1
=
+ ⋅ + ⋅
where:
● V
A
is the phase A voltage
● I
A
is the phase A current
● I
N
is the residual current of the protected line (derived from phase currents)
Chapter 5 - Configuration P543i/P545i
90 P54x1i-TM-EN-1

GE P24DM Specifications

General

Brand	GE
Model	P24DM
Category	Control Unit
Language	English