TS 880 TRANSFER SWITCH
PM064 REV8 10/01/25 27 Thomson Technology
located on the yokes determines the operating point of these limit switches. Should
adjustment be required, consult Thomson Technology for further information.
The transfer switch mechanism has three possible positions:
a) Utility power switching device closed and generator power switching device
open;
b) Generator power switching device closed and utility power switching device
open;
c) Both utility and generator power switching devices open, but NEVER both
utility and generator power switching devices closed at the same time.
7.2.2. EQUIPMENT INSPECTION
To maintain mechanical integrity, ensure that:
q All limit switches linkages are correctly adjusted to provide full travel of the power
switching device toggles without exerting unnecessary forces associated with
excessive travel. Ensure that power switching device travel far enough to reset
any internal trip unit. Note: It is more important for the toggle to go fully in the
"off" direction, than in the "on" direction.
q Mechanical interlocking is correct (i.e. one power switching device must be well
open before the other should close.
q All fasteners are adequately tightened.
q The operating linkages are not damaged or bent, and that all bearing points
operate freely.
To maintain electrical integrity, ensure that:
q All electrical connections are clean and adequately tightened. Corroded or loose
power connections will cause destructive heating, and may cause premature
tripping.
q All insulating devices are in place and in good condition.
q No moisture or other contamination is present.
q Electrical conductors are adequately secured away from moving parts.
To maintain operational integrity, ensure that:
q All control devices are in good condition and correctly calibrated.
q All control devices are adequately secured in their plug-in fixtures.
q Failure to correctly maintain an automatic transfer switch may present a hazard
to life and equipment. Full operational testing must be done prior to placing a
transfer switch in service subsequent to any maintenance or repair. Any service
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