Providing Solutions in centrifugal
Speed Switching for Over 65 years
Motor Switch Selector
Basic Operation

Capacitor start/capacitor run motors and capacitor start motors provide continuous voltage sensing information which can be used to extract speed data from the voltage across the motor start (auxiliary) winding. By comparing this start (auxiliary) winding RPM-sensitive voltage to the main AC input voltage (which serves as a reference voltage), the switch determines when the start circuit should be de-energized. The electronic switch interrupts the start circuit current after the motor has accelerated to the cut out speed, and reconnects the start circuit whenever the motor speed has decreased to a preselected cut in RPM level.

Capacitor start/capacitor run motors exhibit current transients and higher voltages across the start switch. This electrical stress is due to the voltage differential which may exist between the start and run capacitors at the instant of switch closure. This stress phenomenon occurs with both mechanical and electronic type start switches. SINPAC® Switches have voltage detection circuitry to minimize the effects of these conditions.
Unit of Measure


Typical Maximum Motor

N/A 3 hp

Typical Full Load Motor Current Rating (230 Volts)

N/A 17 A

Switch Rating Permissible Max Start Capacitor Current

N/A 35 A

Start Circuit Voltage

N/A 230 V

Part Number

N/A 4-7-72035-15-UC1

Typical Cut Out Voltage

N/A 260 V

Typical Cut In Voltage

N/A 70 V

Package Style

N/A 15


N/A CSA E71115 UL

Additional Features


  • Silent Operation - no switch noise
  • Completely Solid-State with No Moving Parts. SINPAC® Switches have no physical constraints to affect their operation. No wearing parts mean high cycling, no arcing contact.
  • Optional inductor for heavy duty operation.
  • Ambient 40 ºC to 65 ºC.
  • Operating Temperature: -40 ºC to 65 ºC (-40 ºF to 149 ºF) [for operation between 65 ºC and 85 ºC (149 ºF and 185 ºF), consult factory.]
  • Operating Voltage: 230 VAC SINPAC® Switch: 190-255 VAC.
  • UL Recognition E71115 and CSA Certification.