Murphy A91 Series Murphymatic Engine Microcontroller 24VDC - A91-24-LC


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17.00 LBS
Estimated Special Order Ship Date:
Approximately 3 - 4 Weeks
Special Order Available:
Increments of 1

The Murphy Engine Micocontroller A91-24-LC is a completely unattended startup/shutdown and run controller for engine-driven equipment. This user-friendly, compact microprocessor-based controller covers all basic start/stop operations plus other features found on more sophisticated and expensive controllers. The microcontroller is available in several configurations and is factory programmed. Certain parameters can be field adjusted without altering the basic control program.


  • Applicable to all types of engines
  • Built in speed sensing circuit with adjustable crank disconnect RPM and adjustable overspeed RPM
  • Three position Selector Switch allows for automatic off or test mode
  • Engine running LED indicator
  • Four, first-out shutdown LED indicators for low lube oil, high temperature, overcrank, overspeed
  • Quality 16 point terminal block
  • Start from either remote contact close to start, open to stop or N.O. contacts close to start, close to stop
  • Relays are plug-in type with LED indicator for fast service and maintenance


  • Murphy Part No.: A91-24-LC
  • Series: A91 Series
  • Power Input: 24 VDC
  • Enclosure: Less Case
  • Standby Power Consumption: <50mA
  • Sensor Input Polarity: Negative (-) 
  • Outputs: Five open collector transistor 500 mA sink; Two relay, 5 Amp maximum at 24 VDC (sourcing)
  • Reverse Polarity Protection: 200 volt peak reverse voltage 
  • On-board Memory: 8k PROM (programmable, read only memory); data retention 10 years 
  • Operating Temperature Range: -20 to 140°F (-25 to 60°C)
  • Operating Humidity Range: 0-95% Non-Condensing 
  • User Trip point Adjustments: Five on-board potentiometers (320° turn) 
  • Test-Off-Automatic Toggle Switch: Three position switch for: 
  • Test: Starts engine in automatic mode and runs until switched off or emergency shutdown occurs
  • Off: Disconnects all power to control circuits. Stop/disables engine from starting and resets shutdown indicators
  • Auto: Automatic start/stop sequencing is initiated by external switches and signals 
  • Cycle Crank Timer: 5 crank attempts 7 seconds each; 4 rest periods 15 seconds each, before overcrank 
  • Overspeed Trip Point Setting: From 2500-9000 Hz 
  • Crank Disconnect Speed Setting: From 400-2500 Hz 
  • Shutdown Time Delay: 15 seconds after engine start; locks out low lube oil, pressure and high temperature
  • Engine Run LED: Turns on when crank disconnect occurs 
  • Shutdown Output: Removes DC output or operates dry relay contacts for engine shutdown (depending on model used) 
  • Start/Stop: SPDT momentary or SPST maintained switches
  • Enclosure Coating: Red enamel 
  • Subpanel Coating: White enamel
  • Shipping Weight: 7 lb. (3.2 kg)
  • Shipping Dimensions: 12 x 12 x 9 in. (305 x 305 x 229 mm)


  • Air/Gas Compressors
  • Standby Generator Sets
  • Fire/Emergency/Flood Pumps
  • Booster/Transfer Pumps
  • Municipal Fresh/Waste Water Treatment
  • Sewage Lift Stations

Product Condition: NEW

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