The Power Experts

ASCO 4000 Series Power Transfer Switches

ASCO 4000 Series Power Transfer SwitchesThe ASCO 4000 Series Power Transfer Switches transfer loads between alternate sources of power regardless of ampacity size efficiently. The 4000 Series Power Transfer Switches boast reliable, field proven solenoid operating mechanisms. Combined with programmable microprocessor controllers with keypad and LCD display, they offer the most advanced method of transferring all types of loads, such as motors, electronic drives, UPS’s and microprocessor based systems. The 4000 Series Power Transfer Switches are available open or enclosed, in ampacity sizes from 30 through 4000 amperes with a limited selection of optional accessories.

ASCO 4000 Series Power Transfer Switches Features

  • Conventional two-position transfer configuration, plus closed and delayed transition modes of operation. All configurations available with either automatic or non-automatic control.
  • 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.)
  • Rated up to 600 VAC, 30 through 4000 amperes.
  • Reliable and field proven solenoid operating mechanism.
  • High withstand and close-on ratings including short time withstand current rating for optimum flexibility in circuit breaker coordination (800-4000 amperes).
  • Solid, switched neutral configurations available.

ASCO 4000 Series Power Transfer Switches Formats

Closed-Transition Transfer Switching
ASCO Automatic Closed-Transition Transfer Switches feature main contacts that overlap, permitting the transfer of electrical loads without power interruption. The switch 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. Available 150 through 4000 amperes.

Closed-Transition Transfer within 5 electrical degrees is achieved passively, without control of engine generator set. Therefore, no additional control wire runs are required between the ATS and engine generator set governor. Plus, 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). Failure to synchronize indication, extended parallel time protection, and transfer switch lock out are standard features.

Delayed-Transition Transfer Switching
ASCO Delayed-Transition Transfer Switches are 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.

  • Available 150 through 4000 amperes.
  • 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.

Non-Automatic Transfer Switching
ASCO Non-Automatic Transfer Switches are electrically operated units which are operated with manual control switches mounted locally or at remote locations.

  • Sizes from 30 through 4000 amperes.
  • Microprocessor based controller provides for addition of optional accessories.
  • Controller prevents inadvertent operation under low voltage conditions.
  • Low control circuit operating currents allow for long line runs between remotely mounted manual control switches and the transfer switch.

Withstand and Closing Ratings

Transfer Switches Specific Breaker Volts Max “Any” Breaker Volts Max Current Limiting Fuse Rating Volts Max
30 480V 10KA 600V 100KA 480V
70, 100, 125, 150 22KA 480V 10KA 600V 200KA 480V
200 22KA 480V 10KA 480V 200KA 480V
230 22KA 480V 10KA 480V 100KA 480V
260, 400, 600 50KA 480V 65KA 240V 200KA 600V
42KA 600V 42KA 480V
35KA 800V
800 -1200 65KA 600V 50KA 600V 200KA 600V
1600 -2000 125KA 480V 100KA 600V 200KA 600V
2600 – 3000 600V 100KA 600V 200KA 600V
4000 600V 100KA 600V 200KA 600V
For more information about ASCO Power Technologies products,
call 800-876-9373 or email