Liebert AC4 User Manual
AC4
Product Specification/Installation Sheet
Description
The Liebert AC4 is ideal for coordinated control of systems with
redundant equipment, such as multiple environmental units or
pumps. When the AC4 controller detects an alarm in an
operating device, the AC4 enables a standby device and controls
the device in alarm as configured, either leaving that device
operating or disabling it.
The AC4 controller can also balance usage of devices by rotating
units through Operating and Standby modes according to a user-defined schedule. This helps keep
redundant equipment operating efficiently and only when needed. The AC4 can perform routine
testing of standby devices and alert personnel if a standby device fails an operating test and
requires attention.
Another capability of the AC4 is monitoring the
status of connected devices and keeping
personnel apprised through local alarming.
The AC4 controller can interface with anything
that closes an electrical contact. To improve
process efficiency and troubleshooting, the
controller tracks data in two types of logs:
alarm and event. The AC4 has a local LCD
interface and an RS232 interface.
When an alarm condition arises, the AC4
displays alarm information, sounds an audible
alarm, changes the state of the common alarm
relay and turns connected devices on or off
according to user configuration.
For other applications, contact your local
Liebert representative or call 1-800-222-5877.
Features and Benefits
• Custom configuration for specific applications
• Alarm and Event logs with time and date
stamp
• Backup and download configuration files
• User interface for configuration and
monitoring via local LCD or RS232 port
• On-board audible alarm
• Configuration data and operating program
permanently stored in nonvolatile
Electrically Erasable Programmable Read
Only Memory (EEPROM) for protection
against power loss
• Real-time clock
• Status LEDs for verification and diagnostics
24VAC power connector
LCD contrast
adjustment
LCD connector
DIP switch 1
Serial interface connector
(RS232/EIA574)
AC4 Components and Key Features
Power On/Off switch
Audible horn
1
Audible horn
jumper
Common Alarm connectors
Digital output status LEDs
Manual Override Switch
(outputs)
Digital output connectors
Status LEDs
Digital output loss-of-power
jumper
Digital input connectors
Digital input status LEDs
Hardware and Components
The AC4 comes standard with an enclosure, a controller board and a liquid crystal display (LCD).
AC4 enclosure - Internal features
Back of LCD
Controller Board
Knockouts and access slots
Ground wire for LCD
Enclosure
The AC4 enclosure features a key lock for added
security. The enclosure is made of metal to
accommodate secure conduit fittings and
protect components against environmental
debris.
AC4 enclosure - External features
Knockouts and
access slots
on top and
bottom
• The enclosure is designed for easy wire
routing and terminations. Access slots for
communication cables and network wires are
located on both the top and bottom of the
enclosure.
• The enclosure is 2-3/4" deep, allowing for
recess mounting in a wall. The enclosure may
also be flush-mounted.
• The enclosure houses the LCD and the
controller board.
Key
lock
LCD for
configuration
and operation
Controller Board
The controller board supports a total of 10
points (four digital inputs, four digital outputs
and two Common Alarm outputs).
The digital inputs are dry contacts. The digital
outputs and Common Alarm outputs are
Form C contact relays. The Common Alarm
output is one output with two sets of contacts.
The point terminations are made using removable terminal blocks. This allows for easier
access to the terminators, streamlining the process of connecting external devices to the AC4.
The controller board is a microprocessor-based
platform for program execution.
The firmware, including the operating system
and user-defined data, is stored in nonvolatile
flash read-only memory. Flash ROM may be
easily upgraded at the job site, simplifying the
process of installing new firmware as it
becomes available.
An RS232 operator terminal port is included
with each controller board for operator devices
such as a simple CRT terminal or laptop PC.
(top and bottom)
Point Type Point Count
Digital input 4
Digital output 4
Common Alarm output 2
Keypad Display
The keypad display is a user interface mounted on the enclosure door of the AC4.
The display provides for complete monitoring
and configuration of the panel and is
password-protected.
The keypad display provides the ability for the
AC4 to operate as a complete standalone
panel.
2
Keypad
display
Loading...