Power Factor Regulation - GE GEK-113045B Manual

3.2 COLLECTOR-RING MOTORS
Power factor regulation is useful in those applications where motors are subjected to high-level transient
impact loads (such as chipper drives). The PF regulator senses the power factor dip that occurs when the
motor is loaded and causes the SCR Exciter to respond with a boosted output. As a result, the pull-out torque
of the synchronous motor is increased for the duration of the transient load. After the load subsides, the regula-
tor senses an excessive leading power factor and causes the SCR to reduce its output. This automatic boost-
ing of field current to avoid pull-out is called field forcing. The Power Factor regulator thus provides automatic
boosting when field forcing is required and economical low field operation when the motor is idling.
Another application of the power factor regulator is to control power factor swings that result from various lev-
els of loading so as not to cause fluctuations in the plant system voltage.
3
The SPM provides the control signal to the variable SCR exciter when PF regulation is required. See the fol-
lowing figure for a functional operation overview of this feature.
3-
16
Courtesy of store.ips.us
Main
Contactor
A
B
C
Voltage Current
Input
Input
PF
Feedback
PF
Detection
SPM
PF Reg
Setpoint Output
Figure 3–13: POWER FACTOR REGULATION
SPM Synchronous Motor Protection and Control
3 SYNCHRONOUS MOTOR APPLICATIONS

3.2.10 POWER FACTOR REGULATION

DC Supply to
Motor Field
MOTOR
Field
Field
Contactor
Proportional
PF
Regulator
Reg Reg Reg
Gain Stability Floor
701754A4.CDR
SCR
Exciter
Control
Signal
GE Multilin