Three phase soft starters

The three phase soft starter connects between the contactor and the motor. Sure-Start3 reduces the starting current and offers a controlled start to limit the damaging start-up and noise in a three phase motor compressor. They are also designed to offer reverse phase protection for motors.

Sure-Start3 soft starter is also designed to learn the motor characteristics of the load. After a few starts, it will have automatically adjusted itself to the load and the electrical supply impedance at the site. Sure-Start3 is designed to function as an auto-start device. Our range of models do not require any auxiliary control input. This makes them much easier to install and are readily compatable with different installations.

Sure-Start soft starters are ETL, CE and RoHS compliant.


Features & Benefits

  • Reduces locked rotor amperage (LRA)/inrush current by up to 40% at startup
  • Reduces Start-up Torque by up to 70% to the motor
  • Voltage protection from brownout and intermittant power failures
  • Automatic optimization of motor current
  • Reduces light flicker
  • Extends life by reducing stress and heating of compressor/motor
  • Allows systems to meet certain utility requirements
  • Auto-Start on power up with no requirement for auxiliary control power
  • Easy installation with minimal wiring required

Motor Protection Functions

  • Low voltage / high voltage shutdown
  • Provides phase reversal protection
  • Delay function limits number of motor starts per hour
  • Internal timing prevents rapid cycling faults
  • Provides brownout protection
  • Prevents fatigue failure of motor bearings, piping and motor foundation structure


  • SS5A04-27SN (460V, 60Hz, 04-27 FLA)
  • SS4A04-34SN (415V, 50Hz, 04-34 FLA)
  • SS3A04-27SN (380V, 50/60Hz, 04-27 FLA)
  • SS2A04-28SN (208-230V, 50/60Hz, 04-28 FLA)


Sure-Start3 Three Phase Submittal


Single and Three Phase Sure-Start Soft Comparisons


Voltage Ratings (ac) 208-230, 380, 415, or 460 volts
Frequency Models available for 60Hz or 50Hz
Motor Power Ratings (208/230V, 50/60Hz) 2-10 hp
Motor Power Ratings (380V, 50/60Hz) 2-15 hp
Motor Power Ratings (415V 50Hz, 460V 60Hz) 2-20 hp
Starting torque reduction Up to 70% of full load torque
Operating Temperature -4°F to 122°F (-20°C to 50°C)
IP Rating 207
Dimensions 5.30" x 2.94" x 1.96" (132mm x 72mm x 59mm)
Material ABS flameproof (UL-94V0)
Software Fault Delay 180 seconds
Software Optimization Auto - Compensates for motor size and supply impedance
Reversal Phase Protection Yes
Allowable duty cycle 20 starts/hr
Initial Power on Delay 1 second
Shutdown on Low Voltage (#SS3-A) Less than 195 volts to neutral
Shutdown on Low Voltage (#SS3S/SS3G) Less than 85% of nominal line voltage
Shutdown on High Voltage (#SS3S/SS3G) Above 111%of nominal line voltage
Power Loss Reset 100ms detection
EMC Compliance N2002