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Asco 4000 Auto Transfer Switch (1Ph, 1000A)

  • Image 1
  • Image 2
  • Microprocessor Controller
  • User Interface
  • User Interface for Closed Transition models
400.00 LBS

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This Asco Series 4000 transfer switch automatically transfers single phase loads up to 1000A. Designed for industrial applications, the Asco 4000 is ideal for transferring all types of loads including motors, electronic drives, UPS's, and microprocessor based systems.


  • Reliable and field-proven solenoid operating mechanism for high speed transfer of loads.
  • Conventional Open Transition (break-before-make) two-position transfer configuration. (Closed and Delayed Transition configurations available - see below.)
  • UL listed to 1008 Transfer Switch Equipment & CSA certified to CSA 22.2 No.178-1978 Automatic Transfer Switches.
  • Qualified to IEC 60947-6-1, CE marked (optional). (Limited to certain accessories.)
  • Front replaceable main and arcing contacts.
  • High withstand and close-on ratings including short time withstand current rating for optimum flexibility in circuit breaker coordination.
  • Programmable microprocessor controller with keypad and LCD display.
  • Industrial grade user interface with integrated controls and indicating lights.
  • Convenient one tine diagram with switch position and source acceptability LED indicators.
  • Standard ground conductor connections.
  • Four auxiliary contacts, two contacts closed when switch is in normal position and two contacts closed when switch is in emergency position.
  • Local/remote communications capability for interfacing with ASCO PowerQuest® or SiteWeb® communication products.
  • Solid neutral, with fully-rated terminals. (AL-CU) UL Listed.
  • NEMA 1 indoor enclosure standard (but see options below).


Asco Series 4000 Microprocessor Controller (Group 5)

  • asco4000-controller-in.jpgAdvanced digital microprocessor.
  • Voltage, frequency, control, timing and diagnostic functions.
  • Microprocessor logic board is separated and isolated from the power board to improve electrical noise immunity performance and assure compliance with rigorous transient suppression standards.
  • Allows the user to easily access detailed information on: system, power source parameters, voltage, frequency and time delay settings, optional feature settings, historical event log, and system diagnostics.
  • A four line, 20 character LCD has a backlit display which enables easy viewing under all conditions (see Asco 4000 Brochure below for screen shots).
  • All screens can be navigated using only six buttons.
  • Touch pad programming of features and settings without the need for meters or variable power supplies.
  • On-board diagnostics provide control panel and ATS status information to analyze system performance.
  • Displays and counts down active timing functions.
  • Selectable multi-language display (English, German, Portuguese, Spanish, or French).
  • Password protection to prevent unauthorized tampering of settings.
  • For more detailed information, see 4000 Series Microprocessor Controllers.

Asco Series 4000 User Interface

  • 4000seriesuserinterface-o-in.jpgConvenient One Line Diagram - Provides a clear view of the position of the transfer switch, as well as the acceptability of the Normal and Emergency sources.
  • Source Acceptability LEDs - Provide true indication of the acceptability of each source, as determined by the voltage, frequency, voltage unbalance, and phase sequence settings of the control panel.
  • Transfer Switch Position LEDs - Provide an indication of which source the transfer switch is connected to.
  • Transfer Test - Allows the user to test the operation of the transfer switch under a simulated failure of the normal source. Holding for 15 seconds allows time for the engine generator to come online and the transfer switch to transfer the load.
  • Retransfer to Normal - Allows the user to bypass the programmed Retransfer to Normal time delay upon the return of the normal source when the switch has transfered to emergency either during normal operation or a transfer test.
  • Lamp Test - Provides a convenient way to verify the functionality of all LEDs on the User Interface.
  • User Controls Locked - Visually displays the status of the keypad lock feature of the control panel. When illuminated, the buttons of the User Interface are disabled and the user must enter a password into the control panel to unlock the switch. When LED is blinking, the controls are temporarily unlocked for five minutes from the last button pressed.

Closed Transition Option (Please Call for Pricing)

  • Features main contacts that overlap, permitting the transfer of electrical loads without power interruption.
  • Transfers in a make-before-break mode if both sources are within acceptable parameters.
  • Control logic continuously monitors source conditions and automatically determines whether the load transfer should be open (conventional non-overlap mode) or closed transition.
  • Closed-Transition transfer within 5 electrical degrees is achieved passively, without control of the engine generator set.
  • No additional control wire runs are required between the ATS and engine generator set governor.
  • Protective relaying may not be required under normal operation since the contact overlap time is less than 100 milliseconds (consult your local utility on protective relay requirements).
  • Extended parallel time protection standard. User interface provides visual indication when the pre-set extended parallel time has been exceeded. The controls automatically open the emergency or normal main contacts. Separate contact also available to shunt trip to an external breaker.
  • Failure to synchronize indication standard. User interface visually displays a failure to synchronize alarm if the time delay settings is exceeded, during closed transition transfer operation.
  • Transfer switch lock out with user interface indication standard. Prevents transfer in either direction if the extended parallel time is exceeded.
  • User interface alarm reset button. Resets extended parallel and failure to synchronize alarms.
  • Closed Transition bypass pushbutton on user interface allows transfer between sources in an open transition mode.

Delayed Transition Option (Please Call for Pricing)

  • Designed to provide transfer of loads between power sources with a timed load disconnect position for an adjustable time period.
  • Applications include older style variable frequency drives, rectifier banks, and load management applications.
  • Utilizes reliable, field proven solenoid operating mechanisms.
  • Mechanical interlocks to prevent direct connection of both sources.
  • Indicator light (LED type) for load disconnect position.
  • Adjustable time delay for load disconnect position.


Asco 4000 Brochure

Asco 4000 Microprocessor Controller

TRANSFER SWITCH OPTIONS (Please Call for Pricing)

  • No neutral or Switched neutral.
  • Other 50/60 Hz voltages up to 600 VAC.
  • Other Enclosures: Open Style, NEMA Type 3R, 4, 4X, or 12.
  • Extended Warranties.


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

  • Accessory 2C Engine Starting Time Delay - Provides an extended time delay on engine starting. The standard feature one time delay is adjustable from zero to six seconds. Accessory 2C allows this time delay to be adjustable from zero to sixty minutes in one second intervals factory set at five minutes.
  • Accessory 6C Reset Switch - for manual retransfer to normal.
  • asco4000-18z-sm.jpgAccessory 18Z Relay Board - Includes one Form C contact (Rated 2A @ 30VDC or 0.5A@ 125VAC) for each of the following: Normal Source Acceptability, Emergency Source Acceptability, Selective Load Disconnect (Pre and post transfer signal time delay for selective load disconnect with a programmable bypass on source failures - adjustable 0 to 5 minutes), and Fourth contact can be set to mimic the acceptability contacts or annunciate any combination of the acceptability contacts and/or any switch alarm conditions available. Extends eninge starting time delay up to 60 seconds.
  • Accessory 14A/14B Auxiliary Contacts - Additional auxiliary contact sets to indicate switch position (two sets come standard).
  • Accessory 30A Load Shedding - Load-shedding circuit initiated by opening of a customer-supplied contact.
  • Accessory 30B Load Shedding - Load-shedding circuit initiated by removal of customer-supplied control voltage. (Specify voltage).
  • acc-44g-sm.jpgAccessory 44A Strip Heater - Prevents condensation and freezing of condensation. External 120 volt power source required. Includes thermostat.
  • Accessory 44G Strip Heater - Prevents condensation and freezing of condensation. Wired to load terminals. Includes thermostat.
  • Accessory 135L Power Meter 5210 - offers local monitoring of power and energy information on the Asco 4000 load side. (Not compatible with other PowerQuest accessories when used with the Asco 4000. For interfacing capability, order the Power Manager 5220XP below.)
  • Accessory 72A Serial Interface Module 5110 - for remote communications to ASCO PowerQuest® or SiteWeb® products. Also allows 4000 Series Transfer Switches to communicate via Modbus/RTU.
  • Accessory 72E Ethernet Connectivity Module 5150 - for remote communications to ASCO PowerQuest® or SiteWeb® products. Contains embedded web pages for the remote monitoring of ASCO products, as well as some 3rd party devices. Also provides Serial-to-Ethernet link with ability to communicate using Modbus/TCP.
  • asco5220-sm.jpgPower Manager 5220 XP - provides real-time power monitoring of Asco 4000 transfer switches and other power systems via optional local LCD display or other PowerQuest interface products. Requires Accessory 72A or 72E.
  • Single Channel 5310 Remote Annunciator - Provides remote monitoring and control of one Asco 4000 transfer switch. Requires Accessory 72E.
  • Eight Channel 5350 Remote Annunciator - Provides remote monitoring and control of up to eight Asco 4000 transfer switches. Requires Accessory 72E.
  • PowerQuest 5710 Essential Critical Power Management System - offers monitoring and control of up to 32 devices from a web browser accessible server with a 23 inch touchscreen.
  • PowerQuest 5750 Professional Critical Power Management System - offers monitoring and control of up to 64 devices from a web browser accessible server with a 23 inch touchscreen.
  • Other options may be available. Please call to inquire.
Model Number:
60 Hz
Withstand Rating:
200kA with current limiting fuses; 50kA with circuit breakers (Short time rating: 36kA - 18 time cycle@ 60Hz)
(4) 1/0 - 600 MCM
Cabinet Type:
NEMA 1 Indoor (See Options)
Service Entrance Rated:
Full Dimensions HxWxD (inches):
72 x 34 x 20
400 lbs.
Limited Warranty:
24 month
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