A completely unattended startup/shutdown and run controller for engine driven equipment. This user friendly, compact, state-of-the-art microprocessor based controller, covers all basic start stop operations plus other features only found on more sophisticated and expensive controllers.

The A91 is designed to operate from a 12 or 24 volt battery, and requires a magnetic sensor (pickup) for speed detection.


■ Microprocessor Based Automatic Controller
■ Field Programmable Trip Points
■ Five LED Signal Indicators
■ Startup Lockout Timer
■ Interfaces With Other Existing Murphy Products
■ NEMA 3R “Weatherproof” Enclosure

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ower Input: 12 or 24 VDC nominal (specify).

Standby Power Consumption: <50mA.

Magnetic Pickup Input: Requires 2 V rms minimum.

Sensor Input Polarity: Negative (-).

Outputs: Five (5) open collector transistor 500 mA sink.
Two (2) relay, 5 Amp maximum at 12 or 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 (5) 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 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.

Warmup Time Delay: Field adjustable from 0-300 seconds to load the engine after warmup (model -WC only).

Cooldown Time Delay: Field adjustable from 0-300 seconds (model -WC only).

Enclosure: Weatherproof NEMA 3R.

Enclosure Coating: Red enamel.

Subpanel Coating: White enamel.

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Palmer Johnson is an authorized distributor and service provider for Murphy by Enovation products.

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