Electric Power

  • Specs Summary
  • Rating Range
  • Transfer Type
    Open / Closed Transition
  • Switch Type
    Contactor Based
  • Input control voltage

ATC Contactor-Based Automatic Transfer Switch

Cat® transfer switches are designed for a variety of standby power applications. They provide flexibility, reliability and value in a compact package. The open and delayed transition contactor-based Automatic Transfer Switch (ATS) provides fully functioning transfer in Applications where a momentary loss of power is acceptable during transfer and retransfers between normal and emergency power supply.

The closed transition contactor-based ATS is designed to Meet application requirements where emergency back up power is required with no momentary loss of power by connecting both sources before the transfer occurs. Closed transition also permits periodic testing of the emergency power source without interrupting power to the loads.

Technical Summary

  • Rating Range 40-1600A
  • Transfer Type Open / Closed Transition
  • Switch Type Contactor Based

ATC Controller Specifications


  • Control Power Wall Mount 40-600A 2 or 3 Pole
    Floor Standing 600A 4 Pole & 800-1200A 2, 3, or 4 Pole
  • Two-position contactors Two-position contactors 40-400A
  • Three-position contactors Three-position contactors 40-1200A
  • System Voltage Application Up to 600 Vac, 50/60 Hz
  • Applicable Testing UL 1008 listed, CSA C22.2 No. 178 certified, IBC 2006, CBC 2007 and OSHPD

Standard Equipment

Contact Composition

  • Caterpillar utilizes silver composition contacts designed to meet the stringent requirements of UL 1008. All contactors are designed so that the contacts can be visually inspected without major disassembly and are protected by arcing contacts.

Controls and Wiring

  • All controls relays and industrial grade relays are totally encapsulated to minimize exposure to dust and dirt. Lugs are 90º rated and all control wire is #16 AWG, type XLPE with a 125º temperature rating.


  • Durable powder-coated steel NEMA 1, 3R or 12 enclosures with three door hinges to ensure proper support of the door and door mounted devices. The hinges have removable hinge pins to facilitate door removal for easy wall mounting or service and are suppli

Optional Equipment

Available Options

  • 2- or 4-position test switch
  • Multi-meter options available
  • Delayed transition or closed transition
  • Selectable automatic or non-automatic operation
  • Space heaters
  • Surge suppression
  • Remote communications
  • Load shed from emergency
  • Controller availability: ATC-100, ATC-300+,and ATC-800
  • Field selectable, multi ratio, control voltage transformer 50/60 Hz

Optional Delayed Transition includes:

  • Time delay neutral
  • Pre-transfer signal with 1 N.O. and 1 N.C. contacts