Single Phase Soft Starters

This product has been developed specifically to soft start large single phase compressors and motors. It provides a dramatic reduction in the starting current but still provides full start torque. It will automaticallyadjust itself to cover the range of 1.75 to 7 hp. It is fully self-contained in a conveniently small, double insulated and flame retardant enclosure.Contact us if you're interested in purchasing our products or need more information.

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

Two Versions Available

  • Primary — includes the function of the contactor

  • Secondary — used in conjunction with an existing contactor


Features & Benefits

  • Rated for motors between 1.75 to 7 horse power electrical
  • Reduces locked rotor amperage (LRA)/inrush current up to 70% at start-up
  • Eliminates light flicker
  • Reduces start-up noise
  • Avoids torque stress fracture on pipes
  • Automatic optimization of motor start-up current
  • Reduced stress and heating of compressor/motor therefore extending the life
  • Allows systems to meet certain utility requirements
  • Easy installation with supplied wiring (special wiring options available)

Motor Protection Functions

  • Protects the compressor/motor from stalling at low voltages
  • Delay function limits number of motor starts per hour
  • Thyristor protected for long life (primary model only)
  • No extra motor contactor needed (primary model only)
  • Provides motor reversal protection during short power outages
  • Internal delay timers prevents rapid cycling in fault conditions
  • Provides brownout protection
  • Self-testing diagnostics (primary model only)


  • SS0B12-20SN (115V, 60/50Hz, 12-20 FLA)
  • SS1B08-16SN (230V, 60/50Hz, 08-16 FLA)
  • SS1B16-32SN (230V, 60/50Hz, 16-32 FLA)




Voltage Ratings (ac) 115, 220-240 Volts
Operating Voltage Range (ac) 95-127, 192-253 Volts
Frequency Models work on 50Hz or 60Hz
Maximum Starting Current 44 amps rms
Maximum Step Starting Current 39 amps rms
Maximum Supply Impedance 0.8 ohms
Control Input 240 volts AC
Operating Temperature -4°F to 150°F (-20°C to 65°C)
Compressor Rated Load Amps (RLA) 32 Amps Max
IP Rating 207
Dimensions 5.30" x 2.94" x 1.96" (132mm x 72mm x 49mm)
Material ABS flameproof (UL-94V0)
Software Cycle Delay 180 sec., defrost cycle compatible (Primary Model)
Software Fault Delay 300 seconds
Software Optimization 1.75 to 7 hp compressors
Duty Cycle 15 starts/hr
Shutdown on Low Voltage (115V) Less than 95 volts
Shutdown on Low Voltage (220-240V) Less than 195 volts
Power Loss Reset 100ms detection
Motor Monitoring Monitors start winding potential
Motor Reversal Shutdown for 180 sec.
EMC Compliance # N2002




Sure-Start vs. Locked Rotor Amperage

Typical Amperage Reduction with Sure-Start

Nominal Tons RefrigerationBefore Sure-StartAfter Sure-Start
84K 183A 55A
72K 150A 40A
60K 130A 36A
48K 100A 29A
36K 75A 23A
24K 50A 15A

Wiring Schematic