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6.5 ZONE REACH TESTS
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 ALPS 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 REACH on
T
page 6–11. The value of I
with respect to I
and to several settings of the relay.
T
NOTE: The pickup voltage calculations at a particular magnitude and phase of I
test. For instance, if a BG Fault was applied, the current angles would be with respect to the phase angle of VB.
The nominal pickup voltage is given by
V
NOM
6
or
V
NOM
a) DEFINITONS
Z = Calculated Impedance
Z
= Relay reach for Z1G, Z2G, Z3G, or Z4G.
R
øZ = Angle of maximum reach.
I
= Test current for I
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.
b) SETTINGS AND CALCULATIONS
1.
Record the following relay protection settings:
(1401), POSSEQANG = [________]
(1402), ZERSEQANG = [________]
(105), Z1GRDREACH = [________] (Zone 1)
(206), Z2GRDREACH = [________] (Zone 2)
6-10
is chosen according to the reach of the zone. The nominal pickup voltage, V
T
⋅
⋅
Z Z
I
R
T
⋅
=
------------------------------------------------------------------- -
(
∅ I ∅ Z
∅ T
)
cos
90°
–
–
+
⋅
⋅
Z Z
I
R
T
⋅
------------------------------------------------------------------- -
=
(
∅ I ∅ Z
∅ T
)
cos
90°
–
–
+
, chosen for the zone.
ALPS Advanced Line Protection System
6 FUNCTIONAL TESTS (USER SETTINGS)
6.5.2 ZONE 1–4 PHASE-TO-GROUND CALCULATIONS
are referenced to the faulted phase under
T
(
∅ I ∅ Z
∅ T
)
cos
90°
–
–
–
(
∅ I ∅ Z
∅ T 90°
)
cos
–
+
–
6.5.1 GENERAL CONSIDERATIONS
, is calculated
NOM
(eq. 6–19)
(
∅ Z
∅ T 180°
)
<
∅ I
<
for
+
–
(eq. 6–20)
∅ Z
<
∅ I
<
(
∅ Z ∅ T
for
180°
–
+
GE Power Management
∅ Z
,
)
.
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