TS 970 Transfer Switch
PM163 REV 0 20/02/05 13 Thomson Power Systems
4.4. TYPICAL COMMISSIONING PROCEDURES
CAUTION
Commissioning procedures must be performed by
qualified personnel only. Ensure the Automatic
Transfer Switch (ATS) ATS Power Chassis and Voltage
Sensing Isolation Plugs PL12 & PL 15 are disconnected
prior to energizing the supply sources. Manually place
the transfer switch mechanism in the neutral position
prior to applying power. Failure to do so may result in
equipment failure or personal injury.
NOTE: The Typical Automatic Transfer Switch Commissioning Procedures Model Series TS
970, Appendix A, is provided for general information only pertaining to typical site installations
and applications. Contact Thomson Power Systems for further information as may be required.
5. AUTOMATIC SEQUENCE OF OPERATION
5.1. STANDARD ATS - OPEN TRANSITION
When utility supply voltage drops below a preset nominal value (adjustable from 70%
to 100% of nominal) on any phase, an engine start delay circuit is initiated and the
transfer to utility supply signal will be removed (i.e. contact opening). Following expiry
of the engine start delay period (adjustable from 0 to 60 sec.) 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. Once the generator voltage and frequency rises above preset
values (adjustable from 70% to 95% of nominal), the engine warm-up timer will be
initiated. Once the warm-up timer expires (adjustable from 0 to 60 min.), the Transfer
to Generator Supply signal (contact closure) will be given to the power contactor
mechanism. The load will then transfer from the utility supply to the generator supply
via the motor operated mechanism.
The generator will continue to supply the load until the utility supply has returned. The
retransfer sequence is completed as follows: when the utility supply voltage is restored
to above the preset values (adjustable from 70% to 95% of nominal) on all phases, a
transfer return delay circuit will be initiated. Following expiry of the Utility Return Timer
(adjustable from 0 to 60 min.), the Transfer to Generator Supply signal will be removed
(contact opening), then the Transfer to Utility Supply signal (contact closure) will be
given to the power contactor mechanism. The ATS will then retransfer the load from
the generator supply back to the utility supply through fast In-phase open transition
transfer sequence.
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