The Facts about 2-wire Motor Design: Split-Phase vs. PSC


Franklin Electric has earned a strong reputation for exceptional dependability over the years by supplying high-quality, reliable and trouble-free products.  That’s why we put a lot of effort into developing and manufacturing the most reliable 2-wire split-phase motor in the industry. What makes the split-phase design—and Franklin’s in particular—stand out from others? Let us tell you!

Basic Design

Biac SwitchIn general, there are two motor designs for 2-wire motors in use today: the split-phase design and the permanent split capacitor (PSC) design. Simply put, the primary difference between the 2-wire split-phase and the PSC designs is the starting method. With a PSC motor design, there are 3 methods of integrating the capacitor into the electrical circuit: 1) in a control box, 2) attached to the bottom of the motor, or 3) integrated into the motor stator.  While the PSC motor uses a permanently-connected capacitor to assist with starting torque, the split-phase motor uses a switching mechanism to engage/disengage the start winding. In the case of the Franklin split-phase design, our 2-wire motors are equipped with the exclusive BIAC switch, designed and manufactured by Franklin, and time-proven for over 25 years in your applications.


Franklin’s BIAC switch has stood the test of time. More than 25years—and millions of motors—in the field. And, with a switch, you don’t have to be concerned about the effect temperature rise on a capacitor.

Starting Torque

Franklin’s split-phase 2-wire motors provide over 30% more starting torque than PSC motors. In addition, only Franklin’s BIAC switch creates Reverse Impact Torque to free sand-locked pumps.

Efficiency and Operating Cost

Don’t be fooled!  We all pay our electric bills based on kilowatts-hours, not amps, so it just doesn’t make sense to equate lower amp usage with lower power costs or better efficiency. Besides that, Franklin’s service factor watt ratings are lower than those of published competitive data. See for yourself:

Efficiency and Operating Costs Chart

So the next time you put a Franklin motor in the well, you should be even more confident that it will stay there….because now you know!