Trane Starters Engineering Bulletin page 71

Figure 49. PFCCs installed downstream of starter contactor, upstream of overloads
Power
Circuit
If the capacitor connection points are downstream of the overload devices, route the PFCC leads
through the overloads as shown in
line- and capacitor-supplied current.
Figure 50. PFCC wires routed through overload protectors
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.
CTV-PRB004-EN
Motor Starter
Contactor
1
2
3
Fusible
Safety Switch
or
Suitable Breaker
Enclosed
Capacitor Unit
Fusible
Safety Switch
or
Overload
Suitable Breaker
Protectors
1
2
3
Power
Circuit
Fuses
3-Phase
Enclosed Capacitor
Capacitor Unit
Overload
Protectors
Motor
Fuses
3-Phase
Capacitor
Figure 50, p. 71.This assures that the overloads register both
Motor
Motor
Starter
Contactor
Starter Options
71