The Zenith ZTS Series of automatic transfer switches (ATS) are built for business and industrial critical applications requiring the reliability and enhanced operation. The ZTS Series uses the MX250 microprocessor control system, which includes features specified for use in business and industrial critical applications. It also provides an intuitive user interface, communications capability and self diagnostics.

The ZTS Series is available in a full range of ampere, voltage and pole configurations, along with an extensive list of options and features.


• ZTS - Standard (Open) Transition
The Zenith ZTS transfer switch is used in general and mixed load applications.

• ZTSD - Delayed Transition
The Zenith ZTSD transfer switch is used to transfer of motor loads, and transformers.

• ZTSCT - Closed Transition
The Zenith ZTSCT transfer switch is used to transfer critical loads where a "no break" transfer is desired with this switch 100msec parallel capability.


Features and benefits

  • Contact transfer speed less than 100 milliseconds
  • High close-in and withstand capability
  • Double throw, interlocked operation
  • Electrically operated, mechanically held by a simple, over-center mechanism
  • Segmented silver tungsten alloy contacts with separate arcing contacts on 600 amps and above
  • Arc quenching grids, enclosed arc chambers and wide contact air gap for superior source-to-source isolation on all units
  • Control circuit disconnect plug and drive inhibit switch for safe maintenance
  • Components accessible for inspection and maintenance without removal of the switch or the power conductors
  • Mechanical indicator and contact chamber cover designed for inspection, safety and position designation


  • Temperature rise test per UL 1008 conducted after overload and endurance tests in unventilated enclosure-exceeds UL requirements
  • UL 1008 listed at 480 VAC
  • CSA certified at 600 VAC
  • Seismic certified to IEEE-693-2005 at HIGH level with 2.5 amplification factor
  • Seismic certified to IBC-2006 at Ip=1.5 for z/h less than or equal to 1
  • Seismic certified to OSHPD using testing standard ICC-ES AC-156
  • ISO 9001 certified manufacturing plant
  • UL 3-cycle (unconditional) short circuit withstand & close ratings
  • OSHPD seismic qualifications

Product Scope

  • Ratings 40 to 4000 amperes
  • 120 - 600 Volts
  • 2, 3 or 4 poles
  • Open type, NEMA 1, 3R, 4, 4X and 12 enclosures
  • 120 to 600 VAC, 50 or 60 Hz
  • Suitable for emergency and standby applications on all classes of load, 100% tungsten rated through 400 amps
  • Available in ZTS (utility-generator), ZTSU (utility-utility), ZTSG (generator-generator) and ZTSM (manual) configurations