Murphy A900 Series manual 1.2Lamp Test Pushbutton Tests the lights on the A903 module

3-6.1.2Lamp Test Pushbutton: Tests the lights on the A903 module.

3-6.1.3Alarm Silence Pushbutton: Turns off any audible alarm that is connected to the Local or Remote Audible Alarm Relays. The indicating light will remain on as long as the condition exists. If the Alarm Silence pushbutton is not operated, the audible alarm will turn off when the alarm contact clears.

3-6.1.4The A903 SELECTRONIC® Control Module includes the following engine control features:

(a)Cycle crank circuit; will crank the engine for 15 seconds then rest for 15 seconds until the engine starts. The crank/rest time is selectable for either 10, 15, 20, 25 or 30 seconds. If the engine false starts, goes above crank disconnect speed then drops below that speed, the control will rest for a fixed 10 second period before cranking again.

(b)Crank Disconnect Speed Switch; this circuit detects engine speed and terminates cranking when engine speed rises above the speed switch setting. The speed switch is adjustable, 25 Hz to 2000 Hz, and is factory set at 1180 Hz. This would be 600 RPM on an engine with 118 teeth on the flywheel ring gear.

(c)Auxiliary Crank Disconnect Circuit; this circuit, required by NFPA-110, is provided as a back up for the Crank Disconnect Speed Switch. It is operated by an external switch sensing either speed, generator voltage or some other variable that could be used to terminate cranking. Either circuit will disconnect the starter when the engine starts.

(d)Overcrank circuit; will stop automatic cranking and indicate overcrank if engine fails to start after 3 attempts. The number of cranks are selectable for 1, 2, 3, 4 or 5 cycles before shutdown. The overcrank circuit may also be turned off so no overcrank shutdown occurs.

(e)Shutdown Time Delay Bypass; this delay prevents the oil pressure, water temperature and loss of speed signal shutdown circuits from operating for 15 seconds after the engine starts as detected by the crank disconnect circuit. This same delay also locks out alarm circuit #7 and #8 when the engine is not running.

(f)Overspeed Speed Switch;

1.Provides a signal to the overspeed shutdown circuit if the engine exceeds the preset speed. The factory setting is approximately 3894 Hz, or 1980 RPM on an engine with 118 teeth on the flywheel ring gear. The adjustment range is 300 Hz to 10,000 Hz.

2.A push to test switch is provided to allow testing of the overspeed circuit without overspeeding the engine. When switch is depressed, the set point of the speed switch is lowered approximately 10%.

3.The push to test switch can also be used to set the overspeed switch at approximately 110% of running speed. Hold the switch depressed while adjusting the setting until the overspeed trips. When switch is released, the set point will be 10% above normal running speed. This is the method used to make the factory setting. With engine speed at 1800 RPM or 3540 Hz.

(g)Cooldown circuit; this circuit keeps the engine running for five minutes after the transfer switch has removed

the load from the generator and signaled the A903 to stop the engine. This feature may be selected (turned On, standard setting is Off) with a switch on the back of the Control / Display Module.

3-6.1.5Seven (7) First-out Shutdown Circuits; provide first- out indication of cause of shutdown. These circuits deactivate the fuel relay and lockout the A903 until reset. Shutdown circuits are activated by the crank disconnect circuit and are not active when the engine is stopped. Six (6) Red Shutdown Indicating Lights are provided. The Remote Shutdown circuit does not have an indicator light.

(a)Overcrank; tripped by the overcrank sensing circuit which counts the number of cranking attempts.

(b)Overspeed; tripped by overspeed switch when engine exceeds a preset speed.

(c)Oil Pressure; tripped by the oil pressure SWICHGAGE® if pressure drops below preset point while the engine is running.

(d)Water Temperature; tripped by the water temperature SWICHGAGE® if engine coolant temperature exceeds the switch setting.

(e)Spare Shutdown; tripped by an external switch. This circuit is provided for an additional shutdown that may be recommended by the engine supplier.

(f)Loss of Speed Signal; tripped by an internal sensing circuit that detects the loss of the Magnetic Pickup frequency signal for the speed switches while the engine is still running. Since the Overspeed shutdown circuit is activated by the frequency input, it prevents the engine from running without overspeed protection.

(g)Remote Shutdown; this circuit is provided to shutdown the engine generator from a remote location. No indicating light is provided.

3-6.1.6Nine (9) Alarm Indicating Circuits; provide indication of cause of alarm. These circuits activate the alarm relays. Alarm circuits are active as long as power is applied to the A903. All are active when the engine is running, shutdown or on standby except alarm circuit #7 and #8 which are locked out until the engine is running. Nine (9) Amber Alarm Indicating Lights are provided however only two circuits are labeled. The other 7 are for customer specified alarms.

(a)Low Water Temperature; operated by low water temperature SWICHGAGE® .

(b)#2 Spare Alarm; operated by an external switch. This circuit is provided for an additional alarm that may be required by the user.

(c)Switch Not In Automatic; operated by the OFF-AUTO- TEST mode selector switch.

(d)#4 Spare Alarm; operated by an external switch. This circuit is provided for an additional alarm that may be required by the user.

(e)#5 Spare Alarm; operated by an external switch. This circuit is provided for an additional alarm that may be required by the user.

(f)#6 Spare Alarm; operated by an external switch. This circuit is provided for an additional alarm that may be required by the user.

(g)#7 Spare Alarm; operated by an external switch. This circuit is provided for an additional alarm that may be required by the user.

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