Baldor Start Capacitor Size Chart, MFD & Voltage Guide

What Is a Baldor Motor Start Capacitor?

A Baldor motor start capacitor is an electrical component used in compatible single phase electric motors to provide additional starting torque. During startup, the capacitor helps create the phase shift required for the motor to begin rotating.

Once the motor reaches the appropriate operating speed, the starting circuit normally disconnects the capacitor through a centrifugal switch, relay, or another control device.

Start capacitors are commonly found in electric motors used for air compressors, pumps, fans, industrial machinery, agricultural equipment, and other applications requiring reliable motor starting performance.

Baldor Start Capacitor Voltage and MFD Ratings

Two of the most important specifications when selecting a replacement motor start capacitor are its voltage rating and capacitance rating.

Baldor Start Capacitor Size Chart

The following chart lists Baldor motor start capacitors by SKU, voltage rating, and MFD range. Click a part number to view its corresponding product on the MDS of Michigan website.

All MFD specifications are expressed in microfarads. Voltage ratings refer to the capacitor rating, not necessarily the motor supply voltage. The MFD specification for EC1645B06 was not included in the supplied product data.

How to Select the Correct Baldor Start Capacitor

Choosing the correct Baldor motor start capacitor requires more than matching its physical appearance. Different capacitors can look similar while having different electrical specifications.

1. Identify the Baldor Capacitor Part Number

Start by checking the part number printed on the existing capacitor or listed in the motor’s replacement parts documentation. Matching the original Baldor SKU is often the most reliable starting point when selecting a replacement.

2. Check the Capacitor Voltage Rating

Start capacitors are available in several AC voltage ratings, including 115V, 125V, 165V, 230V, 250V, and 330V in the chart above.

The replacement capacitor must have a voltage rating suitable for the motor’s starting circuit. The capacitor voltage rating should not be confused with the motor’s incoming supply voltage.

3. Match the MFD Rating

The MFD rating identifies the amount of electrical capacitance provided by the capacitor. For example, a Baldor capacitor rated 189-227 MFD is designed for a different capacitance range than a 340-408 MFD capacitor.

Using an incorrect capacitance rating can affect starting torque, starting current, and motor performance.

4. Verify Capacitor Dimensions and Terminals

Even when two capacitors have similar electrical specifications, their physical dimensions and terminal configurations may differ. Confirm that the replacement will fit the motor enclosure and connect properly to the existing wiring.

5. Confirm Motor Compatibility

Baldor motors may have different replacement components depending on their catalog number and specification number. When possible, use the complete motor information to verify the correct capacitor.

Signs of a Failing Baldor Motor Start Capacitor

A failed or weakened start capacitor may cause noticeable starting problems. Common symptoms include:

• A motor that hums but does not start.
• Difficulty starting under normal operating conditions.
• Slow motor acceleration during startup.
• Overload protection tripping during the starting cycle.
• Visible swelling, cracking, or leakage from the capacitor.
• A motor that intermittently fails to start.

These symptoms do not always indicate a failed capacitor. Problems with the starting switch, wiring, bearings, or other electrical components can produce similar conditions.

What Is the Difference Between a Start Capacitor and a Run Capacitor?

Start capacitors and run capacitors are both used in compatible single phase electric motor circuits, but they perform different functions.

Start Capacitors: Supply additional starting torque when the motor begins operating. They are typically connected to the starting circuit for a short period.

Run Capacitors: Are designed for continuous operation in appropriate motor circuits and help maintain the motor’s electrical performance while running.

Because these components are designed for different operating conditions, start and run capacitors should not be used interchangeably unless explicitly approved by the motor manufacturer.

ABB Baldor Reliance Electric Motors and Replacement Parts

For over 100 years, ABB Baldor Reliance has been committed to manufacturing high quality, dependable electric motors.

As a leading manufacturer of NEMA electric motors, ABB continues this legacy through motor innovation, reliable construction, and products designed for demanding industrial applications.

When you choose an ABB/Baldor product from MDS of Michigan, you receive quality motor and power transmission components supported by an experienced Michigan based team.

MDS of Michigan supplies Baldor start capacitors, electric motors, and other motor replacement components to help businesses maintain their equipment and reduce unnecessary downtime.

Find Your Baldor Start Capacitor at MDS of Michigan

Whether you are replacing a failed capacitor or sourcing motor replacement components for maintenance, MDS of Michigan can help you locate the correct part.

With over 40 years of experience supplying mechanical, electrical, and rubber power transmission products, our Michigan based team works with customers throughout the country to help keep industrial equipment operating.

Browse our Baldor Start Capacitors or contact our team with your motor catalog number, specification number, and existing capacitor information.