TS 880 TRANSFER SWITCH
PM064 REV8 10/01/25 9 Thomson Technology
4. GENERAL DESCRIPTION
Thomson Technology TS 880 series of Automatic Transfer Switches employ two mechanically
interlocked enclosed contact power switching units and a microprocessor based controller to
automatically transfer system load to a generator supply in the event of a utility supply failure.
System load is then automatically re-transferred back to the utility supply following restoration of
the utility power source to within normal operating limits.
The standard TS 880 series Automatic Transfer Switch is rated for 100% system load and requires
upstream over current protection. The TS 880 Automatic Transfer Switch may be supplied with
optional integral over current protection within the enclosed contact power switching units for
applications such as Service Entrance Rated equipment. Refer to Section 6 of this manual for
detailed information on over current protection.
The TS 880 series transfer switches employs a TSC 800 microprocessor based controller which
provides all necessary control functions for fully automatic operation. The TSC 800 controller is
mounted on the door of the transfer switch enclosure and operating status is shown via LED lights
and LCD display module. For further information on the TSC 800 Transfer Controller, refer to
instruction manual PM049.
100A-1200A rated molded case power switching devices used for the utility and generator sources
are operated by an electrically driven motor mechanism in the transfer switch. 800A-4000A rated
insulated case power switching devices used for the utility and generator sources are operated by
internal drive motor operators. The transfer switch mechanism utilizes the power from the source to
which the electrical load is being transferred. The mechanism provides a positive mechanical
interlock to prevent both power switching units from being closed at the same time, which allows an
interrupted open transition “break-before-make” transfer sequence. For transfer switches supplied
with Closed Transition transfer option, the mechanical interlock is removed thereby allowing a
“make-before break” transfer sequence when both sources of power are available. The TSC 800
transfer controller provides a standard neutral position delay timer for open transition transfer
sequences to allow adequate voltage decay during transfer operation to prevent out of phase
transfers.
Note: For the purpose of this manual, the following standard nomenclature is utilized:
q Utility: to indicate the source of primary power
q Generator: to indicate the source of standby power
q Power switching device: to indicate the automatic transfer switch power switching device
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