Functions/features/options

The primary function of the ATC-900 is to accurately monitor power

sources and provide the necessary intelligence to operate a transfer

switch in an appropriate and timely manner. In addition, the ATC-900

provides useful real-time and historical data, reliable two-way

communications, and programming through the device’s faceplate

or Modbus RTU. The ATC-900 features digital signal processor (DSP)

technology to provide and maintain superior precision and versatility

during both programming and data access.

Standard and optional features

A variety of programmable features are available to meet a wide

array of application requirements. Individual features or feature

combinations provide the information required to tailor switches to

individual needs.

Unlike earlier controllers, the ATC-900 comes with standard features

that are ready to use, with the exception of closed transition, current

metering, and Ethernet. Another advancement is that there are four

(4) standard inputs and four (4) standard outputs that the operator

can easily program by choosing from a wide array of predefined

functions. Additional inputs and outputs can be added in groups of

four (4) up to sixteen (16) for a maximum of twenty (20) in total.

Consult section 4.2.1 for I/O specifications.

Product overview

The ATC-900 is a comprehensive, multi-function, microproces

sor- based automatic transfer switch controller. It is a compact,

self-contained, panel-mounted device designed to replace traditional

relay and solid state logic panels (Figure 1 and Figure 2).

The ATC-900 provides an unmatched degree of flexibility to address

the needs of any system. It has an operating voltage range of 60 to

165 VAC at 50/60 Hz (or 24 VDC when using the DCT option). The

ATC-900 can monitor commonly used single-phase or three-phase

voltages and frequencies on normal, emergency, and load buses.

The controller is available in both open and closed transition styles

and can operate most transfer switch mechanisms, including motor

operated breakers, power breakers, and contactors.

The ATC-900 has the same form factor as the ATC-600/800 and an

easy upgrade kit is available for retrofits.

Standard ATC-900 features include:

• Monitoring of normal and emergency source voltages and

frequencies

• Event summary, hi-speed capture, and history information

• Field-adjustable setpoints, including I/O

• Display of system diagnostics, real-time and historical information

through a color 4.3 inch display

• Serial communications (Modbus RTU) and a USB port. Ethernet

communication is optional.

• LED’s integrated on the faceplate for source status indication

(mimic bus)

Safety precautions

All safety codes, safety standards, and/or regulations must be

strictly observed in the installation, operation, and maintenance of

this device.

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 supplies

the load with power from one of these two sources. In the event

that power is lost from the normal source, the transfer switch trans

fers 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.

In automatic transfer switch equipment, the transfer switch’s intel

ligence system initiates the transfer when normal power fails or falls

outside a preset threshold. If the emergency source is a standby

generator, the transfer switch initiates a generator start and will

automatically transfer the load to the emergency source when the

generator voltage and frequency are within setpoint tolerance. When

normal power is restored, the transfer switch automatically transfers

the load to the normal source and initiates a generator shutdown.

Warranty and liability information

NO WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING

WARRANTIES OF FITNESS FOR A PARTICULAR PURPOSE OF

MERCHANTABILITY, OR WARRANTIES ARISING FROM COURSE

OF DEALING OR USAGE OF TRADE, ARE MADE REGARDING

THE INFORMATION, RECOMMENDATIONS AND DESCRIPTIONS

CONTAINED HEREIN. In no event will Eaton be responsible to

the purchaser or user in contract, in tort (including negligence),

strict liability or otherwise for any special, indirect, incidental or

consequential damage or loss whatsoever, including but not limited

to damage or loss of use of equipment, plant or power system,

cost of capital, loss of power, additional expenses in the use of

existing power facilities, or claims against the purchaser or user by

its customers resulting from the use of the information and descrip

tions contained herein. Analyze all aspects of the application, follow

applicable industry standards, and follow the information concerning

the product in the current product catalog and in any other materials.

Introduction

Preliminary comments and safety precautions

This technical document is intended to cover most aspects associ

ated with the installation, application, operation, and maintenance

of the ATC-900. It is provided as a guide for authorized and qualified

personnel only in the selection and application of the ATC-900.

Please refer to the specific WARNING and CAUTION in Section 1.1.2

before proceeding.

If further information is required by the purchaser regarding a

particular installation, application, or maintenance activity, an Eaton

representative should be contacted.

NOTICE

WHEN PROVIDING CUSTOMER SUPPORT AN EATON REPRESENTATIVE

MAY REQUEST IDENTIFYING ATC-900 PRODUCT INFORMATION INCLUDING

THE FIRMWARE VERSION LEVEL. THIS INFORMATION CAN BE FOUND BY

VIEWING THE SYSTEM SETTING DISPLAY SCREENS. IF THE ATC-900 IS

NON-FUNCTIONAL PLEASE REFER TO THE LABEL AFFIXED TO THE REAR.

Description

Eaton’s ATC-900 brings intelligence, adaptability, supervisory and

programming capabilities to automatic transfer switch equipment.

Extreme reliability makes the ATC-900 ideal for mission critical appli

cations in healthcare, wastewater, data center and other industries.

Typically used for utility-to-utility, utility-to-generator, generator-to

generator and three source transfer systems, the ATC-900 can

address virtually any system requirements.

Ease-of-use is a major benefit of the ATC-900 controller. With a

simple, powerful user interface, many intuitive operating features are

included. LED indications and a color display provide high visibility.

Simple arrow keys are used for quick screen navigation. No codes

or abbreviations are used to avoid potential confusion and/or slow

operation, and data screens are grouped for ease of viewing and

editing.

The ATC-900 includes two styles, open or closed-transition, and

offers a variety of monitoring and control features such as selective

load shedding, remote load testing, and event logging/recording.

Flexibility is another important benefit, allowing field configurability

and expandability in the future with add-on accessory modules and

hardware. For retrofit applications, an upgrade kit is available from

the ATC-600/800 to the ATC-900.