Automatic Transfer Switches

A bypass isolation switch utilizes loadbreak isolation and bypass transfer power contacts. Thus, should voltage be lost on the line to which the ATS is connected, and should a manual bypass be required to the other line, this can be accomplished safely and quickly as described below. With contactor designs utilizing non-loadbreak isolation and bypass switches, manual bypass to the other line is hindered by mechanical or electrical safety interlocking.

Application Description
The bypass isolation switch is designed for applications where maintenance, inspection and testing must be performed while maintaining continuous power to the load. This is typically required in critical life support systems and standby power situations calling for safe system maintenance with no power disruptions. Such a design allows for the quick removal of the different switching devices for inspection, maintenance or replacement.

Available Logic Controllers

• ATC-600 Open Transition IQ Transfer Controller
  more information
• ATC-800 Closed Transition IQ Transfer Controller
  more information

Click here for a side-by-side comparison of the controllers.


Features, Benefits and Functions
The Eaton bypass isolation transfer switch is a rugged, compact design utilizing Magnum power switches or Magnum power circuit breakers to transfer essential loads from one power source to another. Open transition switching devices are interlocked to prevent both switching devices from being closed at the same time. The versatile design, in addition to standard transfer functions, offers an optional integral thermal and short circuit protection in either or both switching devices.

The switching devices are in a compact vertical arrangement. The logic can be easily disconnected from the switching device without disturbing critical connections. The enclosure is free standing, and, by using the specially supplied cleats, the switch is seismic approved (Option 42). The terminals are mounted in the rear of the switch, permitting rear, top, bottom or side cable or bus bar entrance. The switching devices have a high withstand rating.

The high-speed, stored-energy switching mechanism guarantees a transfer time of less than 3 cycles.

Features

• Reliable microprocessor logic for open or closed transition
• Eliminates need for complex interlocks.
• Most versatile bypass isolation transfer switch available.
• Eaton drawout cassette design.
• Overcurrent protection available.
• No loadbreak when bypassing to the same source.
• Drawout capabilities on both ATS and Bypass portions.
• Ability to test power switching elements during drawout process.
• Power switching devices completely interchangeable between ATS and Bypass portions.

Standards and Certifications
Eaton transfer switch equipment is listed for application by UL and CSA. In addition, Eaton ATSs are listed in File E38116 by Underwriters Laboratories under Standard UL 1008 and CSA Spec 178. This standard covers requirements for ATSs intended for use in ordinary locations to provide for lighting and power as follows:

1. In emergency systems, in accordance with Articles 517 and 700 in the National Electrical Code (NEC), American National Standards Institute/National Fire Protection Association (ANSI/NFPA) 70 and the NFPA No. 76A and/or


2. In standby systems, in accordance with Article 702 of the NEC and/or


3. In legally required standby systems in accordance with Article 701 of the NEC. Eaton ATSs are available to meet NFPA 110 for emergency and standby power systems, and NFPA 99 for health care facilities when ordered with the appropriate options. Since Eaton ATSs utilize specially designed switches and/or switching devices as the main power switching contacts, these devices must also be listed under the additional UL Standard 1066.

UL utilizes two basic types of listing programs:

• Label Service
• Re-Examination
UL 1066 employs a label service listing program which requires an extensive follow-up testing program for listed devices. Standard UL 1008 for ATSs lists devices under the re-examination program which only requires a continual physical re-examination of the components used in the product to ensure consistency with the originally submitted device. Follow-up testing IS NOT required by UL 1008. Representative production samples of switches and switching devices used in Eaton ATSs are subjected to a complete test program identical to the originally submitted devices on an ongoing periodic basis per UL 1066. The frequency of such a re-submittal can be as often as every quarter for a low ampere device.


4. IBC seismic qualified.