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Product Description and Specifications

Series: ZBTS
Applications: Business and Industrial Critical
Amperage: 100 – 4,000
Poles: 2, 3 or 4
Voltage: 120 – 600V

The Zenith ZBTS Series of Bypass/Isolation automatic transfer switches (ATS) are built for business and industrial critical applications requiring the reliability and enhanced operation. The ZBTS 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.In business and industrial critical applications power cannot be interrupted to perform maintenance of automatic transfer switches. In such circumstances, a bypass/isolation switch is essential and is often required by code.

Zenith ZBTS Series Bypass-Isolation Transfer Switches are the solution when interruption of power during service or testing is not acceptable. Consisting of two major modules-the Automatic Transfer (ATS) and the Bypass/Isolation Switch. The ZBTS Series incorporates the rugged construction of all our ZTS Series automatic switches with a quick make/quick break bypass switch manual load transfer handle and our control/interlock system, which consists of both mechanical and electrical interlocks.

The bypass uses normal failure sensing and a time delay to start the engine automatically if a failure occurs when the ATS has been removed for service-which can be done without disturbing the load.


ZBTS – Bypass/Isolation
The Zenith ZBTS Bypass/Isolation transfer switch is used in general and mixed load applications.

ZBTSD – Delayed Transition Bypass/Isolation
The Zenith ZBTSD Bypass/Isolation transfer switch is used to transfer of large motor loads, transformers, uninterruptible power supplies (UPS) systems or load shedding to a neutral “center” position.

ZBTSCT – Closed Transition Bypass/Isolation
The Zenith ZBTSCT Bypass/Isolation transfer switch is used to transfer critical loads where a “no break” transfer is desired with this switch 100m sec parallel capability.

Features & Benefits

  • Load is not interrupted during bypass & isolation operation
  • High close-in and withstand capacity
  • Automatic transfer switch is located on a draw-out mechanism to facilitate maintenance
  • Emergency power systems can be electrically tested without disturbing the load
  • Power cables do not have to be disconnected to remove automatic transfer switch
  • Bypass to any available source with ATSremoved
  • Engine start circuit maintained during bypass operation; normal power failure causes engine start contact closure even with the ATS removed
  • Diagnostic lights and detailed instructions for simple step-by-step operation
  • Mechanical and electrical interlocks ensure proper sequence of operation
  • Bypass switch contacts are closed only during the bypass-isolation operation
  • Silver-plated copper bus interconnection of the transfer and bypass switches on all sizes


  • 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 C22.2 No. 178 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

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