Instructional Booklet
Page
16
Effective: March 2021
Operation and Maintenance Manual,
Automatic Transfer Switch Controller, ATC-900
For more information visit: www.eaton.com
IB140012EN
Transfer Operation Connections Output Relays K1, K2, K3, K4
K1, K2, K3, and K4 on J6 pins 5 through 12 are factory wired to
operate the transfer switch. The relay contacts for each are rated
for 10 A, 1/3 HP @ 250 Vac. The DC rating is 10 A @24 Vdc.
The K relay outputs are used to control the transfer device. Cer-
tain configurations of power use only the Open K relays. The K
relays default configuration is:
K1 = S2 Open (Trip)
K2 = S1 Open (Trip)
K3 = S1 Close
K4 = S2 Close
The user should refer to the switch drawings for usage. The relays
momentarily energize until the ATC-900 senses that the switching
device has closed or opened (Using AUX-illary contacts) and then
de-energizes the K relay to the normally open state.
4.2.2 Popular Inputs and Outputs (Programmable I/O)
The following are some popular I/Os that can be programmed. See
the I/O Table 8 in Section 5.5 and Appendix B for all of the I/O
Descriptions. A fixed input or output is one that is not user pro-
grammable as it is fixed from the factory. It is tied to a switch or
function of a switch that requires that input or output. If more
than one Programmable Input is set to the same input type, their
behavior is dependent on what type of input they are set to.
Some inputs are Normally Closed, like Lockout and Monitor Mode
– NC, while the rest are Normally Open. For example, if multiple
inputs are programmed for Lockout, opening any Lockout input
will cause a Lockout condition, while all Lockout inputs must be
closed to remove the Lockout condition. On the other hand, if
multiple inputs are programmed for Go To Emergency, closing any
Go to Emergency input will initiate a transfer to the Emergency
Source, while all Go to Emergency inputs must be open to return
to the Normal Source.
Similarly, two or more Programmable Outputs may be set to the
same output type. This allows multiple output contacts to operate
based on the same function.
Lockout (Input)
The Lockout contact is closed to enable normal, automatic opera-
tion. Opening this contact will Inhibit all automatic operation.
This feature is used when non-automatic control is required. The
ATC-900 continues to monitor source status and will accurately
display status on the controller's mimic bus. After the controller
has been locked, the user must reset the controller by simultane-
ously pressing the Help and Enter buttons.
Go To Emergency (Input)
When the Go to Emergency contact is closed, a transfer to the
Emergency Source will be initiated. If the Emergency Source fails
and the Normal Source is available, the ATC-900 will initiate a
transfer back to the Normal Source (failsafe).
The Go To Emergency input is only usable when either Source 1
or Source 2 is preferred. This input will be disabled when the Pre-
ferred Source selection is set to None.
The Emergency Inhibit input takes priority over the Go To Emer-
gency input if both are activated at the same time. In this case,
the generator will start but a transfer to the Emergency Source
will be inhibited until the Emergency Inhibit input is de-activated.
Bypass Timers (Input)
This momentary contact will bypass the timer for TDEN, TDNE,
TDN, TDES, and TDEC. By pushing the Help and Enter buttons on
the front of the controller (Bypass Timer) at the same time the
countdown will be set to 0 for the current countdown. The next
timer will then start. There is also a programmable input that will
allow the bypass timer to be completed remotely if desired.
Go To Neutral (Input)
A maintained closed contact forces the controller to switch to the
Neutral position, thereby disconnecting the load from both
sources.
Manual Re-Transfer (Input)
With manual retransfer enabled, a momentary closure allows the
ATC-900 to proceed with a re-transfer operation at the operators
discretion. Should a failure of the emergency source occur while
waiting for the manual return, the re-transfer proceeds automati-
cally (failsafe).
Emergency Inhibit (Load Shed) (Input)
This input is enabled when the Emergency Inhibit (36) is enabled.
The contact is closed for normal operation. Opening this contact
will activate the Emergency Inhibit input.
If the Emergency Inhibit contact is opened when the load is con-
nected to the Normal Source, no action will be taken if the Normal
Source is available. If the Normal Source is not available, an imme-
diate transfer to the Neutral position will occur.
If the Emergency Inhibit contact is opened when the load is con-
nected to the Emergency Source, the ATC-900 will transfer the
load to the Normal Source if it is available. If the Normal Source is
not available, an immediate transfer to the Neutral position will
occur if the Emergency Source is available.
The Emergency Inhibit input is only active when either Source 1 or
Source 2 is preferred. This input is ignored if the Preferred Source
selection is set to None.
The Emergency Inhibit input takes priority over the Go To Emer-
gency input if both inputs are activated at the same time. In this
case, the generator will start but a transfer to the Emergency
Source will be inhibited until the Emergency Inhibit input is de-acti-
vated. If the preferred source is lost during this time, the switch
will transfer to the Neutral position.
Three Source ATS Control (Primary (output)/Secondary (Input))
The ATC-900 Primary/Secondary (old Master/Slave) controller func-
tionality provides the user with the ability to control a three-source
system consisting of a utility and two generator sources. In a three-
source system, the Primary ATS controls the engine starting and
stopping of the Secondary ATS. See Feature list, 90A and 90B for a
full functionality write-up on page 37.
Note:
The Secondary ATS requires the DCT module for a DC
power input to keep the controller powered or a UPS if desired.
The Primary ATS handles all transfer time delays between the Util-
ity to Generator transfer. The primary is the Generator Start from
the first ATS.
Bypass Safety Interlock Transfer Inhibited (Input Option 81P)
Whenever the contactor bypass has a safety interlock condition
such as: a Door Open, a Contactor(s) not locked in, not in auto-
matic, in Monitor Mode, etc, the automatic transfer functionality
will be inhibited. This input will trigger a warning status that can
be monitored via communications (Serial or Ethernet) and a flash-
ing banner on the controller's display.
There is also a form C contact block that the user can also use,
see the switch's instruction booklet.
