TSC 900 TRANSFER SWITCH CONTROLLER
PM 151 REV 1 15/10/08 Thomson Power Systems
3.4.4. TEST MODE
3.4.4.1. ON LOAD TEST (OPEN TRANSITION TRANSFER)
When an operator selects an ON LOAD TEST mode, the ATS controller will
initiate a simulated utility power failure condition. The transfer switch will
operate as per a normal utility power fail condition with all normal time delays
enabled. The neutral delay circuit logic will be active during transfer to and
from the generator supply (i.e. when both sources of power are available). The
transfer switch will remain on generator supply while in the Test mode. When
the Test mode is manually canceled, the ATS will re-transfer back to the utility
supply following the utility return delay, then the generator will cooldown before
stopping.
3.4.4.2. ON LOAD TEST (CLOSED TRANSITION TRANSFER)
When a load test is initiated in the closed transition transfer mode, the
generator will start and following its warm up delay, the generator will close its
power-switching device when it is in synchronism with the utility supply. If the
transfer switch is supplied with a “Momentary” Closed Transition transfer control
option, the utility power switching device will immediately trip open within ~100
milliseconds after the generator power switching device closes to complete the
“make-before-break” transfer sequence. If the transfer switch is supplied with a
“Soft-Load” Closed Transition transfer control option, the utility power switching
device will remain closed long enough to allow a soft-load power transfer
sequence to be completed as controlled by an external device. The utility power
switching device will then trip open to complete the “make-before-break”
transfer sequence. The generator will continue to supply the load until the test
mode has been removed and the re-transfer sequence is completed as follows:
The utility power-switching device will close when it is in synchronism with the
generator supply via external logic device. If the transfer switch is supplied with
a “Momentary” Closed Transition transfer control option, the generator power
switching device will immediately trip open within ~100 milliseconds after the
utility power switching device closes to complete the “make-before-break” re-
transfer sequence. If the transfer switch is supplied with a “Soft-Load” Closed
Transition transfer control option, the generator power switching device will
remain closed long enough to allow a soft-load power transfer sequence to be
completed as controlled by an external device. The generator power switching
device will then trip open to complete the “make-before-break” re-transfer
sequence.
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