Alpha Technologies AlphaGen 5.0kW Auxiliary Power Unit - Manual (Page 17)

1. System Overview
17
031-132-B0-001 Rev. A TM ©2000
1.4 Engine Control Module Overview
The primary purpose of Alpha’s Engine Control Module (ECM) is to control
and monitor the CE-3X2 Series AlphaGen Auxiliary Power Unit (APU) The ECM
is used in conjunction with a Generator Remote Interface (GRI) PCBA, often
referred to as the Power Board. The ECM/Power Board Assembly is mounted to
the top of the Engine-Generator housing, to the left of the ignition battery. The
Power Board is attached to the ECM via three ribbon cables.
The GRI provides power to the ECM, steps down high voltages for the ECM,
and provides interface connectors for the enclosure sensors, engine controller,
battery sense, ignition battery charger, line sense, and other equipment.
Depending upon the standby powering configuration, the ECM and generator
combination are installed remotely, or collocated, with other Alpha equipment
such as power supplies and batteries.
The Engine Control Module monitors AC line and DC bus status to determine
when to start and stop the APU. In the event of an extended power outage or
low battery bus voltage, the ECM will start the APU to prevent the backup
batteries from discharging to a reduced voltage level which would compromise
the ability of the system to provide a continuous, reliable source of power. The
ECM also controls the ignition battery charger via an on board relay. See
section 1.8 for additional information.
In addition to starting the APU, the ECM monitors the entire system for
abnormal operating conditions such as low engine oil pressure, engine over-
temperature, gas leak, enclosure pad shear, etc. If certain abnormal conditions
or alarms are present, the ECM will either prevent the generator from starting
or shut it down immediately. This provides for public safety, while preventing
any serious damage to the APU. The system operator also has the ability to
override the ECM and control the APU manually or remotely.
Finally, the ECM provides the interface between the APU and Alpha
Technologies' communication devices. The ECM is designed to control and
monitor the APU while responding to commands and queries from a system
controller via an isolated RS-485 data bus. Status information and alarms can
be read from the ECM remotely via the data bus, locally from the Light Emitting
Diodes (LEDs) on the unit’s front panel, or by an optically isolated transponder
interface. The ECM is capable of reporting 9 major alarms, 8 minor alarms, and
2 notifications.