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Asco 300SE Auto Transfer Switch (3Ph, 2000A)

  • Asco 300SE
  • Asco 300SE Diagram
  • Group G Controller User Interface
  • Group G Controller - Sample Screens
  • Group G Controller Board
1,684.00 LBS
Usually ships in 7-10 weeks. Please call for current lead time.
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The ASCO Series 300SE Service Entrance Power Transfer Switch combines automatic power switching with a utility circuit breaker as a disconnect device. This Asco 300 model transfers three phase loads up to 2000A. Rugged construction and proven performance assure the user of many years of reliability. Designed for telecom, commercial, municipal, industrial, and agricultural applications.


  • The Series 300 is listed to UL 1008 standard for Transfer Switch Equipment and CSA standard C22.2 for automatic transfer switches.
  • Meets NFPA 110 for Emergency and Standby Power Systems and the National Electrical Code (NEC) Articles 700, 701 and 702.
  • True double-throw operation: The single solenoid design is inherently inter-locked and prevents contacts from stopping between sources or from being in contact with both sources at the same time.
  • There's no danger of the transfer switch transferring loads to a dead source because the unique ASCO single-solenoid operator derives power to operate from the source to which the load is being transferred.
  • Operating parameters and feature settings can be adjusted without opening enclosure door.
  • Supplied with solid neutral termination. (Optional switched neutral pole available.)
  • Compact design for optimum utilization of space.
  • Designed to be completely front- accessible, permitting the enclosure to be installed flush to the wall and still allow installation of all power cables and connections from the front of the switch.
  • Numerous enclosure options including NEMA 1 (indoor) and NEMA 3R Secure Double Door (outdoor). Models with 3R enclosure now come standard with a 44G strip heater to prevent condensation that can shorten the life of the ATS.


  • Suitable for use as service entrance equipment. Listed to UL 891 (standard for switchboards) and meets all NEC requirements for service entrance use.
  • Circuit Breaker disconnect on the normal for isolation of transfer switch and other electrical equipment.
  • Ground fault trip protection provided.
  • Disconnect link on Neutral and Ground.
  • Silver plated copper ground and neutral bus with solderless screw type terminals.


Asco Series 300 New Microprocessor Controller (Group G)

  • groupg-lcd-sm.jpgEasy to navigate 128x64 graphical LCD display with keypad provides LED indicators for switch position, source availability, not in auto, and alert condition. It also includes test and time delay bypass soft keys.
  • Integrated multilingual user interface for configuration and monitoring.
  • Adjustable time-delay feature prevents switch from being activated due to momentary utility power outages and generator dips.
  • Adjustable time-delays for engine start, engine cooldown, transfer, and re-transfer.
  • Inphase monitor to transfer motor loads, without any intentional off time, to prevent inrush currents from exceeding normal starting levels.
  • Voltage and frequency sensing.
  • Engine exerciser to automatically test backup generator each week with or without load (order Accessory 11BE or 72EE for more engine exerciser options).
  • Statistical ATS system monitoring information.
  • Diagnostic functions.
  • Password protection to prevent unauthorized tampering of settings.
  • Further details can be found in the brochure and controller guide below. See pictures above for informative visuals.


Asco 300 Brochure

Asco 300 SE Supplement

Asco 300 Microprocessor Controller

Asco 300 Warranty


Please Call to Order Transfer Switches With These Options:

  • Delayed Transition configuration (ADTS) for transfer of loads between power sources with a timed load disconnect position for an adjustable period of time of 0-5 minutes.
  • Other 60Hz voltages - up to 600 VAC.
  • 50Hz frequency/voltages.
  • Extended warranties: 3, 4, or 5 years.

Please Note: Some Specs (including withstand ratings, dimensions, and weights) may vary with some of the options above.


Please see the Accessories Tab above for more information and to order. Accessories ordered with your transfer switch will be factory-installed (as applicable).

  • acc-1up-sm.jpgAccessory 1UP UPS Back Up Power - Allows controller to run up to 3 minutes without AC power. (Also available as a customer-installed Field Kit.)
  • Accessory 11BE Feature Bundle - (A) Fully programmable engine exerciser with seven independent routines to exercise the engine generator, with or without loads, on a daily, weekly, bi – weekly or monthly basis. Engine exerciser setting can be displayed and changed from the Group G Controller user interface keypad. (B) Event Log display showing the event number, time and date of event, event type, and event reason (if applicable). A maximum of 300 events can be stored. (C) RS 485 Communications Port on Group G Controller enabled. (D) Common Alarm Output Contact. (Also available as a customer-installed Field Kit.)
  • acc-18rx-sm.jpgAccessory 18RX Relay Expansion Module (REX) - Provides for some commonly used accessory relays, includes one form C contact for source availability of normal (18G), and one contact for availability of emergency (18B). Contact rating is 5 amps @ 30VDC or @ 125 VAC resistive). Additional output relay is provided, the default is to indicate a common alarm. See operator’s manual for configurable options. (Also available as a customer-installed Field Kit.)
  • Accessory 135L Power Meter 5210 - For enhanced monitoring of power and energy information on the load side. Includes shorting block and CT’s. (Also available as a customer-installed Field Kit. Not compatible with Accessory 23GA/23GB.)
  • acc-23g-sm.jpgAccessory 23GA/23GB Load Current Metering Card - Measures either single phase (23GA) or three phase (23GB) load current. Includes CT's. (Not compatible with Accessory 135L.)
  • Accessory 30A Load Shedding Circuit - Initiated by opening of a customer–supplied contact. For ATS only. (Not available as a Field Kit.)
  • Accessory 30B Load Shedding Circuit - Initiated by removal of customer–supplied voltage. Please specify voltage. For ATS only. (Not available as a Field Kit.)
  • Accessory 30AA Load Shedding Circuit - Initiated by opening of a customer–supplied contact. For ADTS only. (Not available as a Field Kit.)
  • Accessory 30BA Load Shedding Circuit - Initiated by removal of customer–supplied voltage. Please specify voltage. For ADTS only. (Not available as a Field Kit.)
  • acc-44g-sm.jpgAccessory 44G Strip Heater - Prevents condensation and freezing of condensation. Wired to load terminals: 208-240, 360-380, 460-480, or 550-600 volts. Contains wiring harnesses for all transfer switch sizes. Includes thermostat. (Also available as a customer-installed Field Kit.)
  • Accessory 62W Audible Alarm - Signals each time the switch transfers to emergency. Includes a silencing feature. City of Chicago requirement. (Not available as a Field Kit.)
  • acc-72ee-sm.jpgAccessory 72EE Quad Ethernet Module - Enables remote monitoring and control capabilities. Includes Accessory 11BE Feature Bundle. (Also available as a customer-installed Field Kit.)
  • Single Channel 5310 Annunciator - Provides remote monitoring and control of one Asco 300 transfer switch. Requires Accessory 72EE. (Not factory-installed.)
  • Eight Channel 5350 Annunciator - Provides remote monitoring and control of one Asco 300 transfer switch. Requires Accessory 72EE. (Not factory-installed.)
Model Number:
208V, 240V, 480V, or 600V
60 Hz
Withstand Rating w/ Circuit Breaker:
85,000 @ 600V
Withstand Rating w/ Fuse:
200,000 @ 600V
(6) 1/0 to 600 MCM
AIC Breaker Rating:
65,0000 @ 480V
Service Entrance Rated:
Frame / Cabinet Type:
Frame G / NEMA 1 Indoor or NEMA 3R Secure Double Door Outdoor (Call for other options)
Full Dimensions HxWxD (inches):
91 x 38 x 48 (NEMA 1)
Full Dimensions HxWxD (inches):
91 x 38 x 48 (NEMA 3R)
Weight (NEMA 1):
1684 lbs.
Weight (NEMA 3R):
2180 lbs.
Limited Warranty:
24 Months
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