Written-Pole® Motor Advantages


True Single-Phase Operation

Belle Written-Pole® single-phase motors are true single-phase motors that do not require phase converters to operate on a single-phase service. The motor's capacitor start/run design is similar in concept to conventional single-phase motors; however the innovative use of Belle Written-Pole® technology allow for dramatically reduced starting currents and increased operating efficiencies compared to conventional single-phase motors.

Low Starting Current

Belle Written-Pole® single-phase motors exhibit starting current requirements comparable to conventional single-phase motors one-fourth their size. This feature reduces annoying voltage sags when starting without requiring users to install complex reduced voltage starters.

Their low starting current dramatically enhances the capability of a single-phase service to support much larger motors than previously thought possible, eliminating the need for costly three-phase service extensions.

Starting and Running Current Comparison
230 Volt Single-Phase

DescriptionWritten-Pole® Single-PhaseConventional Three-PhaseConventional Diesel
Rated Output (hp)757575 (pump hp)
Rated Input Voltage480480NA
Full Load Speed (rpm)18001775NA
Full Load Current (amps)11683NA
Peak Starting Current (amps)220430-575NA
Operating Efficiency (%)94.594.525.0%
Power Factor (pf)Near Unity0.85NA
Input Power (kW at Rated Output)59.259.2179 kW
Input Demand (kVA at Rated Output)59.2 67.7NA
Starting Demand (kVA)101365-420 kVANA
Hourly Operating Cost $6.55 per hour ($0.11 per kWh)$6.55 per hour ($0.11 per kWh)$11.26 per hour ($2.60 per gallon)
Monthly Demand ChargesPeak kVa demand is lower for Written-Pole® single-phase motors than comparable three-phase motors resulting in lower demand bills where applicable.

Three-Phase Performance using Single-Phase Power

While their low starting current and high operating efficiency eliminate the need for three-phase power in many applications, Belle Written-Pole ® single-phase motors also compare favorably to premium efficiency three-phase motors in many areas. In fact, Written- Pole®single-phase motors often go beyond three-phase performance, enhancing the system's performance by reducing starting current requirements to levels below that of three-phase motors and eliminating the need for reactive power through their unity power factor operation.

Three-Phase Performance Comparison
208 Volt Three-Phase, 230 Volt Single-Phase

 Premium Efficiency Three-PhaseWritten-Pole®
Rating (hp) 30 30 Equal
Full Load Amps (line) 7510033% higher
Locked Rotor Amps (line) 47318561% less
Efficiency (%) 94.194.1Equal
Power Factor 0.84Unity19% higher
Input Power (kW) 23.8 kW23.8 kWEqual
Input Demand (kVA) 27.0 kVA23.8 kVA11.9% less

Note: Equivalent line current for a 208 volt three-phase Written-Pole motor would be approximately 66 amps. A Written-Pole® single-phase motor's lower starting current and unity power factor operation provide real-world benefits even when compared to premium efficiency three-phase motors.

Download BELLE v. Diesel Comparison