GE TRANSFORMER MANAGEMENT RELAY 745 Instruction Manual page 156

6.3 A2 METERING
a) MAIN MENU
PATH: ACTUAL VALUES
HARMONIC CONTENT
[ENTER] for more
The 745 can determine the harmonic components of every current that it measures. This allows it to calculate total har-
monic distortion (THD) as well as a harmonic derating factor that can be used to adjust phase time overcurrent protection to
account for additional internal energy dissipation that arises from the presence of harmonic currents.
b) HARMONIC SUB-COMPONENTS
PATH: ACTUAL VALUES
2nd HARMONIC
[ENTER] for more
6
The 745 is capable of measuring harmonic components up to a frequency of 21 times nominal system frequency. An actual
value is calculated for each phase of each monitored winding. The example above shows what is displayed in a typical
case for harmonic components (in this case the second harmonic). Similar displays exist for all harmonics up to the 21
The second harmonic magnitude for each phase current of Windings 1 through 3 are displayed. Values are expressed as a
percentage of magnitude of the corresponding fundamental frequency component.
6-8
Courtesy of NationalSwitchgear.com
A2 METERING HARMONIC CONTENT
ð
2nd HARMONIC
ENTER
[ENTER] for more
ESCAPE
21st HARMONIC
ESCAPE
[ENTER] for more
MESSAGE
THD
ESCAPE
[ENTER] for more
MESSAGE
HARMONIC DERATING
ESCAPE
[ENTER] for more
MESSAGE
A2 METERING HARMONIC CONTENT
ð
W1 (% f0) H2a: 0.0
ENTER
H2b: 0.0 H2c: 0.0
ESCAPE
W2 (% f0) H2a: 0.0
ESCAPE
H2b: 0.0 H2c: 0.0
MESSAGE
W3 (% f0) H2a: 0.0
ESCAPE
H2b: 0.0 H2c: 0.0
MESSAGE
745 Transformer Management Relay
See below.
↓
See page 6–9.
See page 6–9.
2ND HARMONIC
6 ACTUAL VALUES
6.3.2 HARMONIC CONTENT
st
.
GE Multilin