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Asco 4000 Manual Transfer Switch (3Ph, 1200A)

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SKU: 4NTSA31200_5C Category Tag Brand:
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This Asco Series 4000 non-automatic transfer switch is electrically operated with manual control switches mounted locally or at remote locations. Designed for commercial, telecom, and industrial applications, this Asco 4000 transfers three phase loads up to 1200A.


  • 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.)
  • Programmable microprocessor controller with keypad and LCD display prevents inadvertent operation under low voltage conditions and provides for addition of optional accessories.
  • Industrial grade user interface with integrated controls and indicating lights.
  • Convenient one tine diagram with switch position and source acceptability LED indicators.
  • Low control circuit operating currents allow for long line runs between remotely mounted manual control switches and the transfer switch.
  • Standard inphase monitor can be activated for transferring motor loads.
  • 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).
  • UL 1008 Listed and CSA Certified.


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 transfer switch 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

  • 4000-mts-interface-in2.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 to Emergency Button – Allows the user to transfer the load to the emergency source. Must be pressed and held 15 seconds or until the generator starts and runs.
  • Transfer to Normal Button – Allows the user to transfer the load back to the normal power source when acceptability has been restored.
  • Lamp Test Button – 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.
  • Other 50/60 Hz voltages up to 600 VAC.
  • Other Enclosures: Open Style, NEMA Type 3R, 4, 4X, or 12.
  • Extended Warranties.


Accessories ordered with your transfer switch will be factory-installed (as applicable).

  • 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 engine starting time delay up to 60 seconds when connected to an external 24VDC power supply.
  • Accessory 14A/14B Auxiliary Contacts – Additional auxiliary contact sets to indicate switch position (two sets come standard).
  • acc-44g-sm.jpgAccessory 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.
  • Accessory 72EE2 Ethernet Connectivity Module 5170 – Provides easy and reliable Ethernet connectivity to the transfer switch for monitoring and control. 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.
  • Accessory 150A Tech Package – Includes Accessory 135L Power Meter 5210, Accessory 72EE2 Connectivity Module 5170, Accessory 1PS1 UPS with extended 25 second ride through for ATS controller/135L/72EE2, and provisions for customer supplied 24VDC back-up power.
  • Accessory 107G Monitoring Gateway – Monitors the state and performance of your transfer switch and associated devices, including engine-generators, utility power quality meters, surge protection devices, and circuit breakers.
  • Accessory 75/85 Power Meter 5200 Series – Provides real-time power monitoring of Asco 4000 load side (L), normal side (N), or emergency side (M). With LCD display (85) or without (75). Remote monitoring with optional connectivity module and monitoring system.
  • Single Channel 5310 Remote Annunciator – Provides remote monitoring and control of one Asco 4000 transfer switch. Requires Accessory 72EE2.
  • Eight Channel 5350 Remote Annunciator – Provides remote monitoring and control of up to eight Asco 4000 transfer switches. Requires Accessory 72EE2.
  • Eight Device 5705 Remote Annunciator – Provides remote monitoring and control of up to eight devices via Ethernet, RS485, and Discrete Inputs. Applicable devices include transfer switches, engine-generator, load banks, and surge protection systems. Integrates with Building Monitoring Systems and automatically generates NFPA test reports as needed.
  • PowerQuest 5710 Critical Power Management System – Offers monitoring and control of up to 32 devices from a web browser accessible server with a 22 inch touchscreen.
  • PowerQuest 5750 Critical Power Management System – Offers monitoring and control of up to 64 devices from a web browser accessible server with a 22 inch touchscreen.
  • PowerQuest 5790 Critical Power Management System – Offers monitoring and control of up to 128 devices from a web browser accessible server with a 22 inch touchscreen.
  • Other options may be available. Please call to inquire.
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Cabinet Type

Service Entrance Rated

Full Dimensions HxWxD (inches)


Limited Warranty


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