Zenith ZBTS-D Bypass Isolation Delayed Transition Series ATS

The ZBTS-D Series incorporates the features of the ZBTS Bypass-Isolation Switch with those of the ZTSD unit for transfer of large motor loads, transformers, uninterruptible power supplies (UPS) systems, or load shedding to a neutral “off” position.

In critical systems such as those of hospitals and airports, power cannot be interrupted for maintenance and testing of automatic transfer switches (ATSs).

In such circumstances, a bypass-isolation switch is essential and often required by code. The GE Zenith Controls ZBTSD Series Delayed Transition Transfer/Bypass-Isolation Switch meets requirements for inspection and/or maintenance of the delayed transition transfer switch without power interruption.

The ZBTS-D Series incorporates the rugged construction of all our ZTS Series switches with a quick-make/quick-break manual load transfer handle and our control/interlock system, consisting 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.

Features and Benefits

  • Load is not interrupted during bypass operation
  • High close-in and withstand capability
  • Temperature rise test per UL 1008 conducted after overload and endurance tests in unventilated enclosure – exceeds UL requirements
  • Available in ZBTS (utility-generator), ZBTSU (utility-utility), ZBTSG(generator-generator) and ZBTSM (manual) configurations; models include standard, delayed, and closed transition
  • 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 transfer switch
  • Bypass to any available source with transfer switch removed
  • 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

Product Scope

  • Ratings 100 to 4000 amperes
  • 2, 3 or 4 poles
  • Open type, NEMA 1, 3R, 4, 4X and 12
  • Available with ZTS, ZTSD and ZTSCT Series Transfer Switch
  • Bypass and transfer switch have identical ratings
  • Suitable for emergency and standby applications on all classes of load, 100% tungsten rated through 400 amps
  • UL 1008 listed at 480 VAC
  • CSA C22.2 No. 178 certified at 600 VAC
  • IEC 947-6-1 listed at 480 VAC

Product Specifications:  Brochure for ZBTS Series (pdf)