Keystart control modules provide manual start/stop and automatic fault protection for generators, pumps and other engine-driven applications.

Outputs allow control of engine fuel (energized to run), starter motor and preheat. The Keystart also has an alarm output for remote or audible warning of faults. Six LEDs and icons indicate engine status and faults. Four switch inputs (closing to negative on fault) enable automatic shutdown on engine low oil pressure, high coolant temperature and auxiliary faults. Model 9621 has a fully adjustable engine overspeed shut-down feature, configurable for either generator AC or magnetic pickup speed signals. Charge alternator excitation and a charge fail warning LED are standard.

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Power Supply

  • Operating voltage, steady state: 7 to 30VDC
  • Operating voltage, brown out/cranking: 5VDC minimum
  • Current consumption: <100mA


  • Fault switch inputs: close to negative DC during fault
  • Generator AC input (model 9621 only): 70 - 270 VAC rms, <50 to >60 Hz nominal
  • Magnetic pickup input (model 9621 only): 3.5 - 21 VAC rms, <2000 to >6500 Hz nominal

Outputs (all ratings non-reactive)

  • Run (fuel): positive DC, NO relay contacts, 10A max @ 24VDC
  • Start (crank): positive DC, keyswitch contacts, 10A max @ 24VDC
  • Alarm: negative DC (open collector transistor), 300 mA max
  • Speed calibration: to suit 0-1mA, 75 Ohm meter, output=0.75mA at rated engine speed.

Adjustable settings

  • Preheat timer: 0 or 10 secs, default = 0 secs
  • Fault override timer: 2 to 20 secs (VR1), default = 10 secs
  • Overspeed trip level (model 9621 only): 100 to 130% (VR3) of nominal calibrated speed, default = 110% (of 50 or 60 Hz)


  • Case material: polycarbonate / polyester
  • Overall dimensions: (w x h x d): 3.8 x 3.8 x 3.7 in. (96 x 96 x 95 mm)
  • Panel cut-out size: DIN 3.6 x 3.6 in. (92 x 92 mm)
  • Weight: approx 0.7 lb. / 300g
  • Operating temperature: -31° to 131°F / -35° to 55°C
  • Electromagnetic compatibility: EN55022, class B
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