Alpha Technologies APU Control Module (ACM) - Manual (Page 8)

018-340-B0-001 Rev. A 8
1.0 System Overview
1.1 Introduction
The primary purpose of Alpha’s APU Control Module (ACM) is to control and monitor
generator systems that utilize the ACU Module. Depending upon the standby powering
confi guration, the ACM and generator combination are installed remotely, or co-located, with
other Alpha equipment such as power supplies and batteries.
The ACM monitors AC line and DC bus status to determine when to start and stop the APU.
In the event of an extended power outage, self test initiation, remote start command or low
battery bus voltage, the ACM will start the APU. The APU will 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.
In addition to starting the APU, the ACM monitors the entire generator system for abnormal
operating conditions such as engine over-temperature, gas leak, enclosure pad shear, etc. If
certain abnormal conditions or alarms are present, the ACM and or the APU controller (APS-
CP, A2034 Logic PCB, CCG or ECI-2) 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 ACM and control the APU
manually or remotely.
Finally, the ACM provides the interface between the APU and Alpha Technologies’
communication devices. The ACM 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 ACM remotely via the data bus,
locally from the Light Emitting Diodes (LEDs) on the unit’s front panel, or by an optically
isolated analog transponder interface. The ACM is capable of reporting 7 major alarms, 6
minor alarms and 2 notifi cations.