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 automatically adjust 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.

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
  • Provides motor reversal protection during short power outages
  • Internal delay timers prevents rapid cycling in fault conditions
  • Provides brownout protection
  • Self-testing diagnostics


  • 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 Current44 amps rms
Maximum Step Starting Current 39 amps rms
Maximum Supply Impedance0.8 ohms
Control Input240 volts AC
Operating Temperature-4°F to 150°F (-20°C to 65°C)
Compressor Rated Load Amps (RLA)32 Amps Max
IP Rating207
Dimensions5.30" x 2.94" x 1.96" (132mm x 72mm x 49mm)
MaterialABS flameproof (UL-94V0)
Software Cycle Delay 180 sec., defrost cycle compatible (Primary Model)
Software Fault Delay300 seconds
Software Optimization 1.75 to 7 hp compressors
Duty Cycle15 starts/hr
Shutdown on Low Voltage (115V)Less than 95 volts
Shutdown on Low Voltage (220-240V)Less than 195 volts
Power Loss Reset100ms detection
Motor MonitoringMonitors start winding potential
Motor ReversalShutdown for 180 sec.
EMC Compliance #N2002



Sure-Start vs. Locked Rotor Amperage

Typical Amperage Reduction with Sure-Start

Nominal Tons Refrigeration Motor Size Before Sure-Start After Sure-Start
84K 7hp 183A 55A
72K 6hp 150A 40A
60K 5hp 130A 36A
48K 4hp 100A 29A
36K 3hp 75A 23A
24K 2hp 50A 15A

Wiring Schematic