ASCO Series 185 Automatic Transfer Switch. 


Why Should You Choose An ASCO Automatic Power Transfer Switch?


Customer service, rock-solid dependability, and the industry’s highest performance have made ASCO the first choice in emergency power for more than 80 years.


Our power transfer switches are used in more emergency power backup systems worldwide than any other.


ASCO is the name behind most of the technological advances in transfer switch design, and we have more patents than all other manufacturers combined. ASCO transfer switches are the first choice for installations of every kind, from homes and small businesses to the largest financial data centers and hospitals in the world.


Performance Sets The Series 185 Apart


The Series 185 Automatic Transfer Switch incorporates the latest technology developed by ASCO for dependable operation in any environment


  • When utility power fails for just 1 second or more, the Series 185 Automatic Transfer Switch signals the generator to start
  • In less than 30 seconds your electrical power is normally restored
  • Once the Serie S 185 Automatic Transfer Switch senses utility power has reached an acceptable voltage level for a period of time, it automatically reconnects your power
  • It then smoothly shuts the generator down after an adjustable 2 - 5-minute cool-down period to extend generator life
  • The user-friendly control panel also allows you to manually run a test at the push of a button
  • LED indicators to let you know the availability of both power sources and transfer switch positions


ASCO Series 185 Residential/Light Commercial Automatic Transfer Switches

Product Features

  • User-friendly control interface with intuitive symbols and visual indicators to inform operator of transfer switch and power source status
  • Listed to UL 1008 for optional standby systems, handling total system load including motors and all other electrical loads
  • cUL Listed for Canadian Installations
  • Meets Article 702, NFPA-70 National Electric Code (NEC) requirements
  • Nominal service voltage 240V 50/60Hz, Single Phase, 3 wire AC systems
  • Available in 100 through 400A ratings
  • 200A and 400A Service Entrance designs feature disconnect circuit breaker on normal source
  • True double-throw contacts with inherent mechanical interlocking to prevent connection of generator and utility sources
  • Terminals for convenient connection of neutral and ground conductors
  • Available in NEMA Type 1 Indoor (steel) and Type 3R Outdoor (aluminum) enclosures, with hinged door design
  • Suitable for controlling standby generators with 2-wire automatic starting circuits
  • Available in manually operated version, up to 230A•Available from stock
  • 24-hour support, call 1-800-800-ASCO


Time Delays

  • Adjustable 1 or 3-second time delay to override momentary normal source outages to delay transfer switch and engine starting signals
  • Transfer to emergency time delay - fixed at 10 seconds
  • Retransfer to normal time delay - fixed at 5 minutes
  • Adjustable 2 or 5 minutes unloaded running time delay for emergency engine cooldown
  • Four - second-time delay to ignore momentary voltage and frequency transients during initial Genset loading


Optional Accessories


Strip Heater


A strip heater with a thermostat is recommended for extremely cold areas to prevent condensation and freezing of this condensation. An external 120-volt source is required

Ordering Information


ASCO Series 185 Residential Microprocessor Controller


Control and Interface Panel ASCO Sereis S 185 Microprocessor Controller

The ASCO group 4 Microprocessor Controller is used with all sizes of the Series S 185 Power Transfer Switches. Includes as standard all of the voltage, frequency, control, timing, and connectivity functions required for most optional standby power applications. 


Voltage And Frequency Sensing

  • Adjustable single phase sensing on normal source
  • Normal source pickup voltage is adjustable to either 198 volts or 209 volts; drop-out is adjustable to four incremental settings, 154 volts, 176 volts, 187 volts, or 198 volts
  • Frequency sensing on the emergency source. Pickup is 57 Hz (nom 60 Hz) or 48 Hz (nom 50 Hz), and dropout is 51 Hz (nom 60 Hz), and 43 Hz (nom 50 Hz)


Standard Selectable Features

  • Engine exerciser to automatically test backup generator each week - Includes control switch for testing with or without load
  • Selective load disconnect, double - throw contact to operate at an adjustable 0 - 20-second adjustable time delay prior to transfer and reset 0 to 20 seconds after transfer
  • 60 Hz or 50 Hz selectable switch


Remote Control Feature

Terminal provisions for connecting

  • Remote test switch
  • Remote test switch with automatic transfer
  • Remote time delay bypass switch

Control And Interface Panel

  • User - friendly control interface with intuitive symbols and visual indicators to inform operator of transfer switch and power source status


Performance Features

  • 240 volt spacing per UL and CSA standards
  • Meets or exceeds the requirements of the following regulatory agencies:

    • UL 1008

    • CSA C22.2 No. 178

    • IEC 60947-6-1

    • NFPA 110

  • Meets or exceeds the requirements for Electromagnetic Compatibility (EMC)

    • IEC60947-6-1 and CISPR Radiated and Conducted Emissions

    • IEC61000-4-2 Electric Discharge

    • IEC61000-4-3 Electromagnetic Field Immunity

    • IEC61000-4-4 Electrical Fast Transients

    • IEC61000-4-5 Surge Immunity

    • IEC61000-4-6 Conducted Disturbances

    • FCC CFR 47 Part 15

ASCO Transfer Switchs


    ©2021 by Aurora Generators Inc.

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