GE 745 TRANSFORMER MANAGEMENT RELAY, Instruction Manual

Page: 83 / 408

GE Power Management 745 Transformer Management Relay 5-33
5 SETPOINTS 5.4 S2 SYSTEM SETUP
5
5.4 S2 SYSTEM SETUP 5.4.1 DESCRIPTION
This group of setpoints is critical for the protection features to operate correctly. When the relay is ordered, the
phase and ground CT inputs must be specified as either 5 A or 1 A. The characteristics of the equipment
installed on the system are entered on this page. This includes information on the transformer type, CTs, VT,
ambient temperature sensor, onload tap changer, demand metering, analog outputs and analog input.
5.4.2 TRANSFORMER
In order to provide accurate and effective transformer protection, the parameters of both the transformer and
the system configuration must be supplied to the 745 relay.
yy
SETPOINTS
yy
S2 SYSTEM SETUP
This message indicates the start of setpoints page
S2 SYSTEM SETUP
. Press
to view the contents of this page, or to go on to the next page.
y
TRANSFORMER
y
[ENTER] for more
This message indicates the start of the TRANSFORMER section. To continue
with these setpoints, press , or press to go to the next
section.
NOMINAL FREQUENCY:
60 Hz
Range: 60 Hz / 50 Hz
Enter the nominal frequency of the power system. This setpoint is used to
determine the sampling rate in the absence of a measurable frequency.
Frequency is measured from the VT input when available. If the VT input is
not available, current from phase A of Winding 1 is used.
FREQUENCY TRACKING:
Enabled
Range: Enabled / Disabled
In situations where the AC signals contain significant amount of sub-
harmonic components, it may be necessary to disable frequency tracking.
PHASE SEQUENCE:
ABC
Range: ABC / ACB
Enter the phase sequence of the power system. Systems with an ACB
phase sequence require special considerations. See Section 5.2.4: PHASE
SHIFTS ON THREE-PHASE TRANSFORMERS on page 5–6 for details.
TRANSFORMER TYPE:
Y/d30
°
Range: See Table 5–1: TRANSFORMER TYPES on page 5–10.
Enter the transformer connection from the table of transformer types. Phase
correction and zero-sequence removal are performed automatically as
required.
If
TRANSFORMER TYPE
is entered as
2W
or
3W EXTERNAL CORRECTION
with a DELTA/WYE power transformer, the
WINDING 1/2/3 PHASE CT
PRIMARY
setting values must be divided by on the DELTA
current transformer side to compensate the current magnitude.
With this correction, the 745 will properly compare line to neutral
currents on all sides of the power transformer.
For example, for a 2-Winding DELTA/WYE power transformer with
•WYE connected current transformers on the DELTA side of the
power transformer (25000:5 ratio)
•DELTA connected current transformers on the WYE side of the
power transformer (4000:5 ratio)
Set: TRANSFORMER TYPE = 2W External Connection
WINDING 1 PHASE CT PRIMARY = 25000:5
WINDING 2 PHASE CT PRIMARY = (4000 / ):5 or 2309:5
M E SSA G E
S ET PO INT
E N T E R
M E SSA G E
WARNING
3
3