an automatic-start, two-cycle, engine-driven generator, and include the shutdown and alarm points recommended in NFPA- 110-1988 “Emergency and Standby Generator Systems” for Level 1 installations. These controllers also meet or exceed the minimum requirements of NFPA-99-1990 “Health Care Facilities” and with the addition of a Low Water Level alarm, the Canadian standard CAN/CSA-C282-M89 “Emergency Electrical Power Supply for Buildings”. The suffix numbers -12 and -24 indicate the engine starting battery voltage.
3-1.2.1The A901-2 series control includes an “Air Damper Closed” light and “Overspeed Relay” to trip the air shut-off solenoid on overspeed of a two-cycle engine.
3-1.3A902-12 and A902-24: These models are designed for an automatic-start, four-cycle, engine-driven generator, and include the shutdown and alarm points recommended in NFPA-110- 1988 “Emergency and Standby Generator Systems” for Level 2 installations. The suffix numbers -12 and -24 indicate the engine starting battery voltage.
3-1.4A902-2-12 and A902-2-24: These models are designed for an automatic-start, two-cycle, engine-driven generator, and include the shutdown and alarm points recommended in NFPA- 110-1988 “Emergency and Standby Generator Systems” for Level 2 installations. The suffix numbers -12 and -24 indicate the engine starting battery voltage.
3-1.4.1The A902-2 series control includes an “Air Damper Closed” light and “Overspeed Relay” to trip the air shut-off solenoid on overspeed of a two-cycle engine.
3-1.5A903-12 and A903-24: These models are designed for an automatic-start, four-cycle, engine-driven generator, and include the shutdown and alarm points recommended in NFPA-110- 1988 “Emergency and Standby Generator Systems” for Level 2 installations plus seven unlabeled alarms that the user may specify and an “Alarm Silence Switch”. The suffix numbers -12 and -24 indicate the engine starting battery voltage.
3-1.6A903-2-12 and A903-2-24: These models are designed for an automatic-start, two-cycle, engine driven generator, and include the shutdown and alarm points recommended in NFPA- 110-1988 “Emergency and Standby Generator Systems” for Level 2 installations plus seven unlabeled alarms that the user may specify and an “Alarm Silence Switch”. The suffix numbers -12 and -24 indicate the engine starting battery voltage.
3-1.6.1The A903-2 series control includes an “Air Damper Closed” light and “Overspeed Relay” to trip the air shut-off solenoid on overspeed of a two-cycle engine.
3-1.7Table 3-1.7 illustrates the alarm and shutdown require- ments of NFPA-110, NFPA99 and CAN/CSA-C282-M89 and compares the features of the A900 series controls to those requirements.
3-2 A901.
3-2.1Control / Display Module. The Control / Display Module, figure 3-2.1, 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 four-cycle engine.
3-2.1.1Mode 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.
6-1/2 in.
(165 mm)
| Low Water | Overcrank |
| Temperature | |
| Loss of Speed | Overspeed |
| Signal | |
| Lamp Test | Oil Pressure |
| AUTO | Water |
| Temperature |
| |
9-3/4 in. | OFF | |
TEST | |
(248 mm) | |
| |
| Switch | Low Oil Pressure |
| Not In AUTO | PreAlarm |
| Low Fuel | High Water Temp. |
| Level | PreAlarm |
| High Battery | Battery Charger |
| Voltage | AC Failure |
| Low Battery | Alarm Silence |
| Voltage |
| |
Figure 3-2.1
(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.
3-2.1.2Lamp Test Pushbutton: Tests the lights on the A901 module.
3-2.1.3Alarm 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.
3-2.1.4The A901 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 can be selected 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.
