Eaton ATC-900 - Page 48

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Instructional Booklet
Page 48 Effective: March 2021
Operation and Maintenance Manual,
Automatic Transfer Switch Controller, ATC-900
TDND/TDNR & TDED/TDER Timers Transition Flowchart Example
Connected to
Normal
No Timers
Counting Down
Disconnected
from both
TDNE
Counting Down
Connected to
Normal
TDND
Counting Down
Normal
Available
Normal Unavailable
Emergency Unavailable
TDND > 0
Connected to
Normal
TDND/TDNE
Counting Down
Normal Available, Commit to Transfer Off
(Clear TDND/TDNE)
Normal Unavailable
Emergency Available
TDND > 0
TDNE > 0
Disconnected
from both
No Timers
Counting Down
D
i
s
c
o
n
n
e
ct
f
r
o
m
N
o
r
m
a
l
Disconnect from
Normal
C
o
n
n
e
c
t
t
o
E
m
e
r
g
e
n
c
y
y
y
Connect to
Emergency
C
o
n
n
e
c
t
t
o
N
o
r
m
a
l
Connect to
Normal
TDND = 0
Disconnected
from both
TDNR
Counting Down
Normal Available
(Set TDNR)
Emergency Available
(Set TDNE)
Emergency
Unavailable
(Clear TDNE)
Normal Available
(Clear TDND)
Normal Unavailable
(Set TDND)
Emergency Unavailable
(Clear TDNE)
Emergency Available
(Set TDNE)
TDNE = 0
TDNR = 0
TDND – Time Delay Normal Disconnect (0-10 sec)
TDNE – Time Delay Normal to Emergency (0-9999 sec)
TDNR – Time Delay Normal Reconnect (0-60 sec)
Disconnected
from both
TDNE/TDNR
Counting Down
TDNE= 0
Normal Unavailable
Emergency Available
TDNE > 0
Normal Available
Emergency Unavailable
TDNR > 0
Normal Unavailable
Emergency Unavailable
Normal Available
Emergency Available
TDNR > 0
TDNE > 0
Normal Available
(Set TDNR)
Normal Unavailable
(Clear TDNR)
Normal Unavailable
(Clear TDNR)
Emergency Available
(Set TDNE)
Emergency
Unavailable
(Clear TDNE)
TDNE= 0
Commit = 0
&
TDNR= 0
D
i
s
c
o
n
n
e
c
t
f
r
o
m
N
o
r
m
a
l
Disconnect from
Normal
TDND = 0
Note: Commit to Transfer overrides TDNR = 0
for Emergency Available and TDNE > 0