IB140012EN
For more information visit: www.eaton.com
Instructional Booklet
Effective: March 2021
Page
49
Operation and Maintenance Manual,
Automatic Transfer Switch Controller, ATC-900
Connected to
Emergency
No Timers
Counting Down
Connected to
Emergency
TDEN
Counting Down
Disconnected
from both
TDER
Counting Down
C
onnec
t t
o
E
mergenc
y
y
y
Connect to
Emergency
C
onnec
t t
o
N
orma
l
Connect to
Normal
Emergency Available
(Set TDER)
Emergency Unavailable
(Clear TDER)
Normal Available
(fail-safe transfer)
Emergency Available
(Clear TDED)
Emergency Unavailable
(Set TDED)
Connected to
Emergency
TDED
Counting Down
Normal Available
(Set TDEN)
Normal Unavailable
(Clear TDEN)
TDEN = 0
Or
Emergency
Unavailable
(fail-safe transfer)
TDED
–
Time Delay Emergency Disconnect (0-10 sec)
TDEN
–
Time Delay Emergency to Normal (0-9999 sec)
TDER
–
Time delay Emergency Reconnect (0-60 sec)
Disconnected
from both
No Timers
Counting Down
TDER= 0
Normal Unavailable
Emergency Available
TDER > 0
Normal Unvailable
Emergency Unavailable
Normal Unavailable
Emergency Available
Normal Available
Emergency Available
TDEN > 0
Normal Unavailable
Emergency Available
TDED > 0
TDED= 0
Disconnect from
Emergency
Disconnect from
Emergency
Normal Available
(fail-safe transfer)
C
onnec
t t
o
E
mergenc
y
y
y
Connect to
Emergency
Normal Available
(fail-safe transfer)
Note: In all cases above if Normal disconnected for TDND prior to connecting to Emergency, TDNR shall be
set upon Normal becoming available and must reach zero to enable transfers. In cases where TDEN and
TDNR are both counting, both must reach zero to enable transfer.
