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Thomson TS840SE Auto Transfer Switch (1Ph, 100A)


SKU: TS842A0100B1A-D-2-D-MKAA Category Tag Brand:
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Thomson TS 840 SE Automatic Transfer Switches are perfect for agricultural, telecom, and light industrial applications. These switches employ two mechanically interlocked power switching units with a microprocessor based controller to automatically start a generator and transfer system load to a generator supply in the event of a utility supply failure. System load is then automatically retransferred back to the utility supply following restoration of the utility power source to within normal operating limits. The TS840 transfer switch provides an “Open Transition” (i.e. “break-before make”) transfer system with neutral position delay to ensure adequate voltage decay to prevent out of phase transfers. Service Entrance Rated.


Enclosed Contact Power Switching Units

  • Fully enclosed silver alloy contacts provide high withstand rating & 100% continuous current rating.
  • 3 cycle short circuit current withstand
  • Completely separate utility and generator side power switching units.
  • Not damaged if manually switched while in service.

Reliable Motor-Operated Transfer Mechanism

  • Heavy duty brushless gear-motor and operating mechanism provide mechanical interlocking and extreme long life.
  • Safe manual operation permits operation under adverse conditions.

Superior Serviceability

  • All mechanical and control devices are visible and readily accessible.
  • All control wires and power busses are front-accessible.

Quality Assurance

  • ISO 9001 Registered

Seismic Certification

  • TS 840 ATS is certified for installation and operation per the following requirements: IBC 2006 – Section 13, Occupancy Category IV; ASCE7-05 Region 3 (minimum SS=342%)

Safety Standards

  • UL 1008 Automatic Transfer Switches for use in Emergency Systems
  • CSA C22.2 No. 178 Automatic Transfer Switches

Control Features

  • Isolation plug permits disconnecting control circuits from all power sources.
  • TSC 9 microprocessor based controller.
  • USB Port Factory Programming/Diagnostic
  • Normal Operation Status LED Lights: Load on Utility & Load on Generator, Utility & Generator Source Available, Engine Start Activated, Load Shed Activated
  • Diagnostic LEDs: System OK, Alarm, Wait for Transfer, Diagnostic
  • Alarm output (100ma, 24VDC)
  • Three Phase Voltage Sensing on Utility & Generator Sources
  • Generator AC frequency sensing
  • Utility under voltage control set point 70% dropout
  • Generator set points: under voltage 70% dropout, under frequency 90% pick-up
  • Under Frequency Sensor on Generator Source
  • Engine Start Delay Timer 0-10 sec.
  • Engine Cool down Delay Timer 3-300 sec.
  • Engine Warm-up Timer 0-60 sec.
  • Neutral Position Delay 0-60 sec.
  • Utility Return Timer 0-120 sec.
  • Engine Start Contact (10A, 120/240VAC res. Form B)
  • Load shed contact (5A, 120/240VAC res.)
  • Integrated Programmable Generator Exercise Timer (On or Off Load, 7, 14, or 28 day)
  • Exercise initiate pushbutton indication
  • Auxiliary Contact – Utility side (10A, 120/240VAC res. Qty 1, Form C)
  • Auxiliary Contact – Generator side (10A, 120/240VAC res. Qty 1, Form C)
  • Local Utility Power Fail Simulation Test Pushbutton
  • Provision for Remote Load Test/Peak Shave Switch Input

Further Features

  • NEMA 3R Enclosure
  • Solid Neutral
  • Storage Temperature: -40C to 7oC (-4oF to 158F)
  • Operating Temperature: -40C to 5oC (-4oF to 122F)
  • Humidity: 95% non-condensing, maximum

Service Entry Features

  • Service Entrance Labeling
  • Utility Switching Device: Molded Case Switch with Ther-Mag Trip
  • Pad-lockable Service Disconnect Control Switch
  • Key Lockable Enclosure Door
  • Removable Neutral Ground Bond Conductor
  • Utility Overcurrent Protection
  • Service Disconnect Pilot Light
  • Additional Neutral Grounding Per Necessary Requirements
  • Optional generator-side over-current protect with Ther-Mag Trip available – please call for pricing and to order


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

  • Load Distribution Breakers
  • Enclosure Strip Heater w/ Thermostat
  • LCD Service Display Module


TS840 Brochure

TS840 Manual

TS840SE Schematic Drawing

TS840 Warranty






Withstand Rating @ 240VAC


Cabinet Type

Service Entrance Rated

Full Dimensions HxWxD (inches)




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