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6 FUNCTIONAL TESTS (USER SETTINGS)
6.5 ZONE REACH TESTS
Testing the reach of the relay requires a few organized steps, as follows:
1. Choosing a test current (IT) for the impedance of the reach.
2. Calculating the voltage range in which the unit will pick up.
3. Applying the test voltage and currents in accordance with the test procedure.
Equations are given for calculating the pickup voltage for a chosen current magnitude and phase. If you wish to
test the complete characteristic, the software program, ALPS-Test, can be used to generate test currents and
voltage pickups for the complete characteristic. ALPS-Test is included the LPS-D software suite on the GE
Power Systems Products CD.
This section describes how to determine the test currents and voltages for Z1G, Z2G, Z3G and Z4G. The same
procedure is used for each zone to determine the test values. The procedure is as follows:
1. Choose a test current.
2. Calculate the impedance of the zone.
3. Calculate the operate voltage at the test current and impedance.
The test current, I
, is determined from Table 6–1: TEST CURRENT RANGES FOR PHASE-TO-GROUND
T
REACH on page 6–12. The value of I
age, V
, is calculated with respect to I
NOM
The pickup voltage calculations at a particular magnitude and phase of I
faulted phase under test. For instance, if a BG Fault was applied, the current angles would be with
respect to the phase angle of VB.
NOTE
The nominal pickup voltage is given by
V
=
-------------------------------------------------------------------
NOM
(
∅ I ∅ Z
cos
(
∅ Z
∅ T 180°
)
<
∅ I ∅ Z
for
+
–
V
=
-------------------------------------------------------------------
NOM
(
∅ I ∅ Z
cos
∅ Z
<
∅ I
<
(
∅ Z ∅ T
for
–
+
a) DEFINITIONS
Z = Calculated Impedance
Z
= Relay reach for Z1GROUND, Z2GROUND, Z3GROUND, or Z4GRND
R
øZ = Angle of maximum reach
I
= Test current for I
, chosen for the zone
T
op
øT = Characteristic timer of the zone
øI = Test current angle with respect to the faulted phase
K
= Zero-sequence compensation factor of the zone
0
POSSEQANG = Positive-sequence angle of maximum reach
ZERSEQANG = Zero-sequence angle of maximum reach.
GE Power Management
6.5.2 ZONE 1–4 PHASE-TO-GROUND CALCULATIONS
is chosen according to the reach of the zone. The nominal pickup volt-
T
and to several settings of the relay.
T
⋅
⋅
Z Z
I
R
T
⋅
(
cos
∅ T
)
90°
–
–
+
<
, or
⋅
⋅
Z Z
I
R
T
⋅
(
cos
∅ T
)
90°
–
–
+
)
180°
.
LPS-D Line Protection System
6.5.1 GENERAL CONSIDERATIONS
(eq. 6–19)
∅ I ∅ Z
∅ T
)
90°
–
–
–
(eq. 6–20)
∅ I ∅ Z
∅ T 90°
)
–
+
–
6.5 ZONE REACH TESTS
are referenced to the
T
6-
6
11
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