S7 Power Elements; Power Measurement Conventions - GE Multilin 489 Instruction Manual

5.8

S7 Power Elements

5.8.1

Power Measurement Conventions

5–60
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Generation of power will be displayed on the 489 as positive watts. By convention, an
induction generator normally requires reactive power from the system for excitation. This
is displayed on the 489 as negative vars. A synchronous generator on the other hand has
its own source of excitation and can be operated with either lagging or leading power
factor. This is displayed on the 489 as positive vars and negative vars, respectively. All
power quantities are measured from the phase-phase voltage and the currents measured
at the output CTs.
FIGURE 5–13: Power Measurement Conventions
CHAPTER 5: SETPOINTS
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489 GENERATOR MANAGEMENT RELAY – INSTRUCTION MANUAL
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