Murphy Series A900 manual 3-7 A903-2, DC24V DC24V DC24V

(h)#8 Spare Alarm; operated by an external switch. This circuit is provided for an additional alarm that may be required by the user.

(i)#9 Spare Alarm; operated by an external switch. This circuit is provided for an additional alarm that may be required by the user.

3-6.2Relay Module. The Relay Module, figure 3-6.2, includes all of the control, alarm and shutdown relays that are required to make up the generator engine control. Relays are available for operation on either 12 or 24 volt battery systems. Three (3) relays are included for:

positive) as long as the Mode Selector Switch is in either Auto or Test. When the Mode Selector is turned Off, the Control On signal is open. This can be used to signal switch position or to reset an external circuit when the Mode Selector is turned Off.

3-7 A903-2.

3-7.1Control / Display Module. The Control / Display Module, figure 3-7.1, includes the control and test switches, the solid state logic elements, shutdown and alarm TATTLETALE® lights that make up the generator engine control for a two-cycle engine. This module is the same as Model A901-2 except 6 of the alarm circuits are un-labeled. This allows the customer to specify labels other than those recommended in NFPA-110. This model has shutdown and alarm circuits labeled to meet the requirements of NFPA-110, Level 2.

1A

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3A Fuse

DC24V DC24V

DC24V

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6-1/4 in.

(159 mm)

4-1/2 in.

(114 mm)

Figure 3-6.2

3-6.2.1Fuel Relay; this relay provides two outputs, one to energize the engine fuel solenoid and a separate circuit to energize the battery charging alternator field.

3-6.2.2Shutdown Relay; this relay is operated by the shutdown circuits of the Control / Display Module and provides an output that can be used to trip the generator circuit breaker on an emergency shutdown.

3-6.2.3Local Audible Alarm Relay; provides a contact closure to operate a local audible alarm as required by NFPA- 110, Level 1 and Level 2.

3-6.3Status Signals. The relay module also includes three outputs that can be used with external circuits for signaling or control functions.

3-6.3.1The Control On function at terminal 12 is on (closed to negative) as long as the Mode Selector Switch is in either Auto or Test. When the Mode Selector is turned Off, the Control On signal is open. This can be used to signal switch position or to reset an external circuit when the Mode Selector is turned Off.

3-6.3.2The System Ready signal at terminal 13 is on (closed to negative) as long as the Mode Selector Switch is in either Auto or Test and no shutdown TATTLETALE® circuit is latched on. This can be used to signal that the generator engine is ready to automatically start or is running in Test.

3-6.3.3The Control On function at terminal 14 is on (closed to

Figure 3-7.1

3-7.1.1Mode Selector Switch, OFF-AUTO-TEST:

(a)OFF; turns off the control system and resets any shutdown circuits.

(b)AUTO; turns on the engine controls and shutdown circuits. System is on standby waiting for a contact closure to start engine.

(c)TEST; turns on the engine controls and shutdown circuits. A start signal is applied to the automatic control and the engine start sequence begins.

3-7.1.2Lamp Test Pushbutton: Tests the lights on the A- 903-2 module.

3-7.1.3Alarm 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

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