CTV-PRB004-EN
71
Starter Options
If the capacitor connection points are downstream of the overload devices, route the PFCC leads
through the overloads as shown in
Figure 50, p. 71
.This assures that the overloads register both
line- and capacitor-supplied current.
Rule 3—
Accurately size PFCCs that remain connected to the motor when it is offline.
Connecting PFCCs to the load side of the motor-starter contactor is commonly used as a simple,
low-cost way to comply with “Rule 1.” However, the motor may be damaged if the PFCCs are too
large. As a “rule of thumb,” the maximum corrected power factor is 95 percent for a CenTraVac
chiller motor operating at full load.
Failure to comply with this rule can cause significant damage due to voltage regeneration. The
manufacturers of CenTraVac chiller motors place maximum limits on both the corrected power
factor and the capacitor size. PFCCs that remain connected to the motor when it is offline must not
exceed the motor manufacturer’s maximum limit.
Figure 49. PFCCs installed downstream of starter contactor, upstream of overloads
Figure 50. PFCC wires routed through overload protectors
Motor
Fuses
3-Phase
Capacitor
Power
Circuit
Fusible
Safety Switch
or
Suitable Breaker
Overload
Protectors
Enclosed
Capacitor Unit
1
2
3
Motor Starter
Contactor
Fuses
3-Phase
Capacitor
Enclosed
Capacitor Unit
Motor
Starter
Contactor
Motor
Power
Circuit
Fusible
Safety Switch
or
Suitable Breaker
Overload
Protectors
1
2
3
CTV-PRB004.book Page 71 Sunday, December 18, 2011 6:39 PM
