Baldor Oil-Filled Motor Run Capacitor, 370 VAC, for Single-Phase Compressor Motors

Baldor-Reliance oil-filled motor run capacitors rated 370 VAC, the continuous-duty capacitors fitted to Baldor single-phase capacitor-start capacitor-run motors on reciprocating air compressors, pumps and blowers. Stocked in 30, 50 and 60 MFD.

Oil-filled run capacitors are the better-built end of the market and they are what Baldor specifies on compressor duty motors for a reason. The oil acts as the dielectric medium and as a heat sink, which matters because a run capacitor is energised every minute the motor turns, often inside a hot enclosure bolted to a compressor that runs all shift. They still age. Capacitance drifts downward over the years, and a motor running on a tired run capacitor pulls more current, runs hotter and loses torque long before anything actually fails. If a single-phase motor is tripping its overload on warm days, taking longer than it used to to come up to speed, or running hot enough that you cannot keep a hand on the frame, measure the run capacitor before condemning the motor.

Part reference

• E0014: Baldor OC3030F11SP, 30 MFD, 370 VAC.
• E0012: Baldor OC3050F09SP, 50 MFD, 370 VAC. Approximately 2 in. diameter x 3-3/4 in. height.
• E0015: Baldor OC3060F10SP, 60 MFD plus or minus 6 percent, 370 VAC. Approximately 2 in. diameter x 3-3/4 in. length.

Key specifications

• Type: oil-filled motor run capacitor, continuous duty
• Voltage rating: 370 VAC, 50/60 Hz
• Case: round metal can
• Terminals: quick-connect spade

Matching the right capacitor

Match the MFD value to the figure stamped on the capacitor you are removing or printed on the motor nameplate. Voltage may be substituted upward but never downward, so a 440 VAC part will stand in for a 370 VAC part of the same capacitance while the reverse will fail. Capacitance itself has to be matched closely. Fitting a higher MFD value than the design calls for does not improve running torque, it unbalances the auxiliary winding, raises winding temperature and shortens the life of the motor as well as the capacitor.

Safe handling

Run capacitors hold a charge after the motor stops. Isolate the supply and discharge the capacitor across a resistor before touching the terminals, and replace any capacitor whose can is bulged, leaking oil or discoloured rather than testing it in place.

Typical applications

Baldor-Reliance single-phase compressor duty motors, jet and centrifugal pump motors, blower and fan motors, and general-purpose single-phase industrial motors of the capacitor-start capacitor-run type.

Baldor oil-filled motor run capacitors OC3030F11SP, OC3050F09SP and OC3060F10SP, 370 VAC, in 30, 50 and 60 MFD, supplied by AirComParts through the Warthog Air Compressor Store alongside Baldor start capacitors, starter coils, pressure switches and motor overload relays.