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Thomson TS870SE Auto Transfer Switch (3Ph, 400A)


SKU: TS873A0400B1A-x-6-x-NKAA Category Tag Brand:
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This Thomson TS 870 Automatic Transfer Switch is ideal for transferring commercial & industrial three phase loads up to 400A. Service Entrance rated.


  • Employs two mechanically interlocked power switching units with a micro- processor based controller.
  • Automatically starts generator and transfers system load to generator supply in the event of a utility supply failure.
  • Automatically re-transfers back to the utility supply following restoration of the utility power source to within normal operating limits.
  • All load transfer sequences are “Open Transition” (i.e. “break-before-make”) with adjustable neutral position delay to ensure adequate voltage decay for preventing out of phase transfers.
  • Solid Neutral standard on 4 wire systems. (Please inquire about other options.)
  • Fully enclosed silver alloy contacts provide high withstand rating & 100% continuous current rating.
  • 3 cycle short circuit current withstand tested.
  • 10 cycle 6X overload current rating.
  • Completely separate utility and generator side power switching units.
  • Not damaged if manually switched while in service.
  • Safe manual operation permits operation under adverse conditions.
  • Heavy duty brushless gear-motor and operating mechanism provide mechanical interlocking and extreme long life.
  • Superior serviceability with all mechanical and control devices visible and front-accessible, all control wires and power busses are front-accessible, and a plug-in TSC 7320 Transfer Switch Controller.
  • ISO 9001 registered for quality assurance.
  • Seismic Certified for installation and operation per the following requirements: IBC 2012 – Section 13, Occupancy Category IV; ASCE7-05 Region 3 (minimum SS=200%).
  • Certified to CSA 178 & UL 1008 Standards.
  • NEMA 1 indoor standard. Optional NEMA 3R outdoor enclosures also available. (See Option below for other available enclosures.)
  • Note: Molded case circuit breakers or fuses with overcurrent protection are required upstream of the transfer switch.
  • Not Service Entrance Rated.

Service Entrance Features

  • Service Entrance Labeling
  • Utility Overcurrent Protection and Isolating Mechanism
  • Utility Switching Device: Molded Case Switch with Electronic and GF Trip
  • Pad-lockable Service Disconnect Control Switch
  • Status Indications
  • Note: Molded case circuit breakers or fuses with overcurrent protection are still required upstream on the GENERATOR side of the transfer switch, unless transfer switch is ordered with an optional Molded Case Switch with Electronic Trip Generator Switching Device (call for pricing and to order).


  • Isolation plug permits disconnecting control circuits from all power sources.
  • 2.3” back-lit LCD text display for monitoring Utility/Generator voltage, system frequency, operation status, and alarms.
  • Five key menu navigation.
  • Front-panel editing with PIN protection.
  • Customizable status screens.
  • Load on Utility & Load on Generator indication.
  • Utility & Generator Source available indication.
  • 3 Phase Voltage sensing on Utility & Generator Sources.
  • Generator AC frequency sensing.
  • Utility under voltage control setpoint 50 – 95% (adjustable).
  • Generator under voltage control setpoint 50 – 95% (adjustable).
  • Generator under frequency control setpoint 70 – 90% (adjustable).
  • Engine warm-up timer 0-60 min. (adjustable).
  • Utility return timer 0-60 min. (adjustable).
  • Engine start (mains transient) delay timer 0-30 sec. (adjustable).
  • Engine cooldown timer 0-60 min. (adjustable).
  • Neutral position delay timer 0-120 sec. (adjustable).
  • Load Disconnect Contact (LDC) for pre/post transfer control to signal external building systems such as elevators during transfer operations.
  • Up to 16 different date and time schedules for On-load or Off-load Generator exercising.
  • Real-time clock provides accurate event logging.
  • Data logging.
  • Five Programmable Outputs.
  • Five pre-programmed outputs for ATS functionality: Load on Utility, Load on Gen, Load Disconnect Contact (LDC), Fail to Transfer (FTT), and ATS Not in Auto.
  • Local and remote utility power fail simulation test.
  • Engine start contact (8A, 120/250VAC resistive max.).
  • Automatic force transfer to alternate supply should load voltage become de-energized.
  • 24VDC control power.
  • Remote Load Test/Peak Shave Input.
  • Under/Over Frequency Protection- Utility and Generator Sources.
  • 3 Phase Over Voltage Protection – Utility and Generator Sources.
  • Phase Sequence and Phase Rotation Protection between Utility and Generator Sources.
  • Voltage Phase Loss/Unbalance Protection.
  • Programmable Inputs (Quantity 8 Digital Input-voltage free input).
  • ATS Generator Bus Power Metering Capability (Amp, Volt, Freq, kW, kVA, PF).
  • RS485 Modbus Remote Communication Port (Modbus Serial RTU).
  • Serviceable Plug-in Connectors.


TS870 Brochure

TS870 Manual

TSC7320 Controller Manual

TS870 100-800A Quick Start

TS870 100-800A Schematic

TS870 Warranty


  • Employs two electrically interlocked molded case (MCCB/MCS) power switching units and a microprocessor based controller to automatically allow a Closed Transition (make-before-break) load transfer when both utility and generator sources are available.
  • All Closed Transition transfer sequences ensure both sources of power are in synchronism prior to transfer and load is transferred without power interruption.
  • Automatic control & protection circuits ensure the generator and utility supplies are only in parallel for a maximum of 100 milliseconds to permit an uninterrupted load transfer.
  • Reverts to an Open Transition load transfer sequence when only one power source is available.
  • All voltage gap and frequency gap settings are adjustable.
  • Closed Transition Mode can be bypassed to Open Transition Mode within the TSC 7320 Controller.
  • An Auto/Manual Switch is provided for safe Manual operation in Open Transition mode with positive push button controls.
  • Specifically designed and certified to UL 1008 Standards.
  • Ideal for Emergency Power System applications such as commercial, industrial, or government institutions that require automatic standby power and minimal power interruptions to the load.

MORE OPTIONS (Call for Pricing)


  • Bypass Isolation Configuration (400-1200A only, see brochure for details).


  • AUX-BG – Generator Bypass Auxiliary Contact.
  • AUX-BU – Utility Bypass Auxiliary Contact.
  • KOTS-DSE – Key Operated Test Switch- Auto/Off/Engine Start/Test- includes DSE2130 module.
  • R02157 – Programmable Relay Output Expansion Module – Includes eight 2A Resistive 30VDC rate relays – four NO an four Form C Contacts.
  • TS-STG – 24Vdc or 120VAC Shunt Trip Generator Switch (external power source required).
  • TS-STU – 24Vdc or 120VAC Shunt Trip Utility Switch (external power source required).


  • RA7320 (DSE2548) – Remote Annunciator with eight configurable LEDs. Works up to 0.6 miles from the ATS TSC7320 controller. Up to ten modules can be daisy chained.
  • RD7320 (DSE2520) – Remote Display – up to three display modules can be connected to the TSC7320.
  • EMB-TCP/IP (DSE855) – Ethernet ModbusTM Remote Communication Port (ModbusTM TCP).


  • Other Enclosures: NEMA 4X Stainless Steel, and NEMA 12.
  • LCK – Enclosure Lockable Door (Single point T-Handle lock).
  • TS-H1 – Enclosure Strip Heater c/w Thermostat (120VAC external power source required).
  • TS-H2 – Enclosure Strip Heater c/w Thermostat (internally powered from ATS load).


  • TCP – Transfer Switch Connection Plate for Generator Supply (camlocks).
  • TS-SS – Internal Multi-Voltage Selector Switch (208V/240V/480V).
  • LSC – Load Shed – 5-Stage (requires CTK option).


  • LPM-DSE – Transfer Switch Load Power Metering CT Kit (Amp, Volt, Freq, kW, kVA, PF) **Requires CT Kit.
  • CTKxxxx – Current Transformer Kit. Specify CT size: 0100, 0150, 0250, 0400, 0600, 0800, 1200. Require GPM option.
  • MUP – Multifunction Utility Protective Relay – Basler IPS100 (Protection Functions 27, 32, 47, 50/51, 67, 81O/U (Note: May be required by local utility for Momentary CT applications. Please inquire for other makes and models.).


  • SPD – Surge Protection Device.
Model Number



VAC (4-Wire System)



Withstand Rating w/ Circuit Breaker

Withstand Rating w/ Fuse

Lugs per Phase

Cabinet Type

Service Entrance Rated

Full Dimensions HxWxD (inches)


Limited Warranty


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