logic for this application. When the TSC 900 controller receives an input signal for
Closed Transition Transfer Mode, the TSC 900 is configured to operate as follows:
Under normal closed transition operating conditions, the transfer switch operates
automatically during a failure and restoration of utility power and does not require
operator intervention.
When utility supply voltage drops below a preset nominal value on any phase, an engine
start delay circuit will be initiated. Following expiry of the engine start delay period an
engine start signal (contact closure) will be given.
Once the engine starts, the transfer switch controller will monitor the generator voltage
and frequency levels. When the generator voltage and frequency rises above preset
values, a warm up time delay will be initiated. When the warm up timer expires the
transfer to utility supply signal will be removed (logic contact(s) opening) and the transfer
to generator supply signal (logic contact(s) closure) will be given to the transfer switch
Power Switching Devices. The load will then transfer from the utility supply (i.e. opening
the utility power switching device) to the generator supply (closing the generator power
switching device) to complete a break-before-make open transition transfer sequence.
The generator will continue to supply the load until the utility supply has returned and the
retransfer sequence is completed as follows: When the utility supply voltage is restored
to above the preset values on all phases, a utility return delay circuit will be initiated.
Following expiry of the utility return timer, the utility power-switching device will close
when it is in synchronism with the generator supply. If the transfer switch is supplied with
a Fast (Momentary) Closed Transition transfer control option, the generator power
switching device will immediately trip 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 for a longer time period to allow
a soft-load power transfer sequence to be completed via external loading controller. The
generator power switching device will then trip open to complete the “make-before-
break” re-transfer sequence.
An engine cooldown timer circuit will be initiated once the load has successfully re-
transferred back onto the utility supply. Following expiry of the cooldown delay period,
the engine start signal will be removed (remote start contact opened) to initiate stopping
of the generator set.
To Next Page
Loading...
Need help?
General
