GE 469 Instruction Manual page 213
Motor management relay
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Also See for 469:
- Instruction manual (348 pages) ,
- Manual (307 pages) ,
- Communications manual (150 pages)
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A2 Metering Data
GE Multilin
The following is a typical presentation of a three-phase system where current lags
the voltage by 30 degrees.
FIGURE 6–4: Current Lagging Voltage by 30° Display
The phasors shown by the relay and the EnerVista 469 Setup software are a clear
representation of the relationship between the system quantities as seen by the
relay.
The
ACTUAL VALUES
PHASORS
wiring errors. Use the phasors displayed by the relay and the tables on pages 6–18
and 6–21 to determine if VTs and CTs are on the correct phases and their polarity is
correct. Problems arising from incorrect wiring include:
•
Extremely high unbalance levels (CTs),
•
Erroneous power readings (CTs and VTs),
•
Phase reversal trips (VTs).
To correct wiring, simply start the motor and record the phasors. The correct
phasors can be determined using the tables along with recorded phasors, system
rotation, VT connection type, and motor power factor. Note that the phase angle for
Va (Vab if delta) is always assumed to be 0° and is the reference for all angle
measurements.
Common problems include:
•
Phase currents 180° from proper location (CT polarity reversed)
•
Phase currents or voltages 120° or 240° out (CT/VT on wrong phase)
An explanation of how the relay identifies and displays system quantities follows.
Assume that the relay is connected to a balanced three-phase system and that V
V
, V
, and V
are the relay ID names for terminals G2, H1, H2, and G1,
B
C
COM
respectively.
When the relay is set for the "Open Delta" VT connection type, voltages are
measured at terminals G2 (V
measured; however, the corresponding system quantity is calculated, assuming a
balanced three phase system, where V
In the
ACTUAL VALUES
VOLTAGE METERING
phase voltages. The relationship between the displayed and measured quantities is
as follows:
Vab = V
A
Vbc = –V
C
Vca = –(V
+ V
) as calculated
A
C
http://www.GEindustrial.com/multilin
page is a useful troubleshooting tool to identify
) and H2 (V
). The voltage at terminal H1 (V
A
C
+ V
+ V
= 0, leading to V
A
B
C
page, the 469 displays only phase-to-
469
Motor Management Relay
,
A
) is not
B
= –(V
+ V
).
B
A
C
6–15
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