IB140012EN
For more information visit: www.eaton.com
Instructional Booklet
Effective: March 2021
Page
3
Operation and Maintenance Manual,
Automatic Transfer Switch Controller, ATC-900
1.2 Background
Transfer switches are used to protect critical electrical loads
against loss of power. The load’s normal power source is backed
up by a secondary (emergency) power source. A transfer switch is
connected to both the normal and emergency sources and sup-
plies the load with power from one of these two sources. In the
event that power is lost from the normal source, the transfer
switch transfers the load to the secondary source. Transfer can be
automatic or manual depending upon the type of transfer switch
equipment being used. Once normal power is restored, the load is
transferred back to the normal power source. The transfer switch,
in this manual, could be a Power Frame Switch/Breaker, Molded
Case Switch/Breaker, or a Contactor type.
In automatic transfer switch equipment, the switch’s intelligence
system initiates the transfer when normal power fails or falls out-
side a preset threshold. If the emergency source is a standby gen-
erator, the transfer switch initiates generator starting and
transfers to the emergency source when sufficient generator volt-
age is available. When normal power is restored, the transfer
switch automatically transfers back and initiates generator engine
shutdown.
An automatic transfer switch consists of three basic elements:
1. Main contacts to connect and disconnect the load to and from
the source of power
2. A transfer mechanism to affect the transfer of the main con-
tacts from source to source
3. Intelligence/supervisory circuits to constantly monitor the con-
dition of the power sources and thus provide the intelligence
necessary for the switch and related circuit operation
This document deals with the third basic element of the automatic
transfer switch, the required intelligence/ supervisory circuits.
Prior to the introduction of ATC-900, this function was performed
by a door mounted logic panel. The logic panel could be the relay
logic type or the solid state logic type. In either case, the panel
consists of a number of individually mounted and wired devices
offering a limited amount of system flexibility, especially in the
case of the relay logic design. The ATC-900 brings intelligence,
supervisory and programming capabilities, never before available,
to automatic transfer switch equipment.
1.3 Product Overview
The ATC-900 is a comprehensive, multi-function, microprocessor-
based automatic transfer switch controller. It is a compact, self-
contained, panel mounted device designed to replace traditional
relay and solid state logic panels (Figures
2
and
3
).
Designed to meet the needs of markets worldwide, the ATC-900
meets the following standards:
•
ULT 991 Effects of shipping and storage test
•
Thermal cycling test
•
Humidity test
•
UL 1008 Dielectric test
•
FCC Part 15 Conducted/radiated emissions (Class B)
•
CISPR 11 Conducted/radiated emissions (Class A)
•
IEC 61000-4-2 Electrostatic discharge test
•
IEC 61000-4-3 Radiated susceptibility tests
•
IEC 61000-4-4 Fast transient tests
•
IEC 61000-4-5 Surge withstand tests
•
IEC 61000-4-6 Conducted immunity tests
•
IEC 61000-4-11 Voltage dips and interruptions
•
IEC 61000-3-2 Harmonics
•
IEC 61000-3-3 Voltage flicker/fluctuation
•
Seismic IBC/CBC certified
•
CSA conformance C22.2 No. 178-1978 (reaffirmed 1992)
The ATC-900 provides an unmatched degree of programmed flexi-
bility to address the needs of any system. It operates from most
system voltages available worldwide at 50 or 60 Hertz (and 24
VDC using the CT Module option). In addition, a period of no con-
trol power operation is provided. The ATC-900 monitors the condi-
tion of the 3-phase line-to-line voltage and frequency of both the
Normal and Emergency sources. It can also be programmed for sin-
gle-phase operation. The ATC-900 provides the necessary intelli-
gence to insure that the switch operates properly through a series
of programmed sensing and timing functions.
The ATC-900 will form fit into the opening of the ATC-600/800
and an easy upgrade kit is available for previous switch wiring.
A standard ATC-900 will:
•
Monitor Normal and Emergency source voltages and frequen-
cies
•
Provide second to none Event Summary, Hi-Speed Capture, and
History information
•
Permit customer programming including I/O
•
Display real time and historical information through a color 4.5
inch TFT display
•
System diagnostics through the display
•
All I/O are available to the user
•
Features are opened to user
•
Provides serial communications (Modbus RTU) and a USB port.
Ethernet communication optional.
•
Provide faceplate source/load status indications (MIMIC bus)
1.4 Functions/Features/Options
The primary function of ATC-900 is to accurately monitor power
sources and provide the necessary intelligence to operate a trans-
fer switch in an appropriate and timely manner. In addition,
ATC-900 provides useful present and historical data, reliable two-
way communications, and programming through the device’s face-
plate or communications. ATC-900 features digital signal proces-
sor (DSP) technology to provide and maintain superior precision
and versatility during both programming and data access.
1.4.1 Operational Simplicity
From installation, to programming, to usage, the ATC-900 was
designed with operational simplicity in mind. Only one style needs
to be considered, regardless of input/output requirements or sys-
tem voltages and frequencies. ATC-900 provides the functionality
of numerous other devices combined in one package that mounts
in less than 7 by 11 inches of panel space.
The user friendly front panel interface simplifies routine operation,
programming, data presentation and setting adjustments. A large
color display provides flexibility and ease of use. The operation of
front panel membrane pushbuttons moves the ATC-900 display
from function to function or step to step within menus. A single
LED at the top of the faceplate provide an immediate indication as
to the device’s operational mode. An integrated Help Mode provides
immediate user assistance in the form of English language message
displays through the use of a front panel Help pushbutton.
The ATC-900 is communications ready, including Modbus 485,
Ethernet (External), and USB for thumb drives (memory sticks).
