Instructional Booklet
Page 8 Effective: March 2021
Oper ation and Mainten ance Man ual,
Auto m atic Tran sfer Switch Con trol ler, ATC-900
For more information visit: www.eaton.com IB140012EN
Figure 2 . ATC-9 0 0 (Top Left, and Right Side Views).
2.5 External Hard war e
External hardware is viewed as any optional device mounted
directly to or remotely from the ATC-900, such as a DCT Module,
I/O Module, or an Ethernet device. Since the ATC-900 is always
supplied with the necessary communications ports, these modules
can be retrofitted to the ATC-900 at any time. It is recommended
that the control power to the ATC-900 (J7) be removed prior to
connecting or disconnecting the modules. See Figures 2, for con-
nections and section 2.5.2 for interface connections.
2.5 .1 DCT Module Description (Integrated Metering)
The DCT (Direct Current-Current Transformer) Module is a current
transformer interface to the ATC-900 allowing current to be
metered along with voltage and frequency that is already inte-
grated into the controller. The DCT Module simply secures to the
ATC-900 back using four #8 x less than 1/2 inch screws. With
the DCT module installed, the depth of the two units is 3.60
inches. The ribbon cable then plugs into J14 (see Figure 3). When
equipped with a DCT module and CTs, the ATC-900 serves as a
multifunction power meter and provides multifunction measure-
ment of most electrical parameters including voltage, current,
power, frequency, energy, etc. The meter capabilities is specified
as a 1% class energy meter. The information is displayed on the
color display on the front of the ATC-900. Readings can also be
monitored through the RS-485 modbus on the controller. The DCT
is used to measure load current when selective load shed is
enabled.
The DCT Module also has a 24 Vdc input for powering the ATC-
900 controller. If 120 VAC and 24 Vdc is supplied to the control-
ler simultaneously, then the 120 Vac will be the powering supply.
61F is an option to add a DCT module and a 24VDC power supply
with a power buffer. This will allow the controller to stay on over
20 seconds when power is removed, more than enough time to
ride through the power loss. The controller will then be able to
continue to communicate over ie, the Modbus.
The following Table 1 is a list of readings and accuracy available
on the display. Accuracy is for 5 amp secondary WYE or Delta
connections. The meter was tested at the full range of tempera-
tures. The accuracies stated are for the meter components (DCT
Module and ATC-900) only, not the CTs. CTs can be ordered
with different accuracies (typically in the 1-2% range). Accuracy
also can be affected by the CT not being in the correct range of
the current being measured, i.e. using a 600:5 CT for a 400 amp
application. Although not a revenue meter, the measurements are
highly accurate for most applications.
RIGHT SIDE VIEW
LEFT SIDE VIEW
J15 S1 & S2 Generator
Start
J4 (4 Programmable Form C
Dry Outputs)
J5
J1, J2, J3
Connectors
J12 User Modbus
K1=S2 Open
K2=S1 Open
K3=S1 Close
K4=S2 Close
J7
Control Power
Sources 1 and 2
TOP VIEW
J4 Source
Available Outputs
J9
4 Programmable
Wet Inputs
J6
RS-232
J14
DCT
Earth Controller Ground
J8 USB Front Panel Interface
(Thumb Drive)
J11 I/O
Module(s)
SW1 Modbus
Terminator
Module
J13
RS-422
Interface
Source/Load
Interface
Switch Position
Contacts
ATC-900 Eaton Open Transition part number 8160A90G01
ATC-900 Eaton Closed Transition part number 8160A90G64
DCT Module part number 70C1778G01
I/O module part number 70C1776G01
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