GE KVGC 202 - 9.7.7 Load Check Procedure

K
VCG202/EN M/H11
Technical
Manual
KVGC202
Set the logic link LOG7 to ‘0’. Repeat the above tests and this time the RunAway function
should not cause blocking of the ‘Raise volts’ or ‘Lower volts’ relay contacts. ‘RunAway’
relay contacts should operate as it did in the above tests.
[Restore the following settings:
- initial time delay setting (tINIT),
- intertap delay (tINTER),
- the maximum tap position (TP>),
- minimum tap position (TP<)].
9.7.7 Load Check
When the line drop compensation facility is used, check by applying a load down the line
to prove that the polarities of the VT and CT are connected to the relay correctly. Large
load current will provide a more conclusive result.
Calculate the expected voltage drops for both the Resistive and Reactive components in
the line at the CT rated primary current and convert these to secondary valued using the
VT ratio.
Vr =






3 x Ip x R
VT ratio
V
XL
=






3 x Ip x X
L
VT ratio
Where:
Ip = primary rated current of line CT
R = resistive component of line impedance
X
L
= reactive component of line impedance
VT ratio = ratio of primary to secondary voltages of line VT
[Before making the following changes note the settings for: Vr and V
X
, deadband setting
dVs, initial time delay setting (tINIT)].
Set the:
- Vr and V
X
to the calculated values.
- deadband setting dVs to 3%,
- initial time delay setting (tINIT) to 0 seconds].
At the receiving end of the feeder measure the phase to phase voltage on the secondary
of the VT. Repeat this at the feeding end on the same pair of lines.
Set Vs to the value measured at the receiving end. The relay should not cause tapping if
all CT and VT connections are connected with the correct polarity.
If tapping occurs then either CT and VT are not connected correctly or that the Vr and V
X
settings do not match the line Vr, V
X
.
Increase and decrease the Vs setting and record the settings at which the ‘Raise volts’
contacts and the ‘Lower volts’ contacts change state. If the average values of these two
voltages are within 2% of the remote end value, then the relative connections to CT and
VT are correct.
[Restore the following settings:
- Vr and V
X
,
- deadband setting dVs,
- initial time delay setting (tINIT)].
Note: The commissioning engineer should ensure that after completing
all tests that all required settings are set for the relay.