Thermal Model - GE 269Plus Instruction Manual

B THERMAL MODEL & BIAS FEATURE
APPENDIX BB THERMAL MODEL & BIAS FEATURE
Discrete time based algorithm, 250 ms update.
If Unbalance input to thermal memory is enabled, the increase in heating is reflected in the
thermal model. If RTD Input to Thermal Memory is enabled, the feedback from the RTDs will
correct the thermal model.
NOTE
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Courtesy of NationalSwitchgear.com
Figure B–1: THERMAL MODEL
269Plus Motor Management Relay

THERMAL MODEL

B.1 THERMAL MODEL
LEGEND
U/B ... Unbalance
I/P ..... Input
Iavg... Average three phase
current
Ieq .... Equivalent average
three phase current
Ip ...... positive sequence
current
In ...... negative sequence
current
K ....... constant multiplier
that equates In to Ip
FLC... Full Load Current
FLC TCR... FLC thermal
capacity reduction
setpoint
TC..... Thermal Capacity
used
RTD BIAS TC... TC value
looked up from RTD
bias curve
B-
1
B