Eaton ATC-300 - Automatic Transfer Sequence

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Instruction Booklet
Effective: August 2010 Page 29
ATC-300 2-Postion Contactor 
Based Transfer Switch
Figure 24. Utility - Generator Transfer Switch.
Utility - Generator Transfer Switch
Source 1 is available
Close Source 1
(Energize K1)
Source 1 is powering the load
Source 1 becomes unavailable
(or Engine Test, Plant Exercise, Go To Emergency)
TDES timer times out
Send "Engine Start" signal
(Energize Gen Start relay)
Is Source 2
Available?
TDNE timer times out
Open Source 1
(Energize K2)
Close Source 2
(Energize K2)
Source 2 is powering the load
Is Source 1
Available?
TDEN timer times out
Ye s
No
No
Ye s
Sends pretransfer signal
TPRE timer times out
(If Source 1 is Available)
Open Source 2
(Energize K1)
Close Source 1
(Energize K1)
Source 1 is powering the load
TDEC timer times out
Remove "Engine Start" signal
(De-energize Gen Start relay)
Sends pretransfer signal
TPRE timer times out