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Thomson TS870 Auto Transfer Switch (3Ph, 800A)


SKU: TS873A0800A1C-x-5-x-KKAA 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 800A.


  • 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 900 Transfer 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 enclosure 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.


  • Isolation plug permits disconnecting control circuits from all power sources.
  • 7” color touch screen graphical display for monitoring 3 Phase Utility/Generator voltage, system frequency and timer countdown operation.
  • Front Panel Programming using touchscreen graphical display with password security.
  • Latest Technology 32 Bit Microcontroller Architecture provides fast, accurate reliable operation.
  • 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 70 – 95% (adjustable).
  • Generator under voltage control setpoint 70 – 95% (adjustable).
  • Generator under frequency control setpoint 70 – 90% (adjustable).
  • Engine warm-up timer 0-60 sec. (adjustable).
  • Utility return timer 0-30 min. (adjustable).
  • Engine start timer 0-60 sec. (adjustable).
  • Engine cooldown timer 0-30 min. (adjustable).
  • Neutral position delay timer 0-60 sec. (adjustable).
  • Load Disconnect Contact (LDC) for pre/post transfer control to signal external building systems such as elevators during transfer operations.
  • Programmable Generator Exercise Timer (EXT) with easy to use event, Calendar Based, On-load or Off-load Programmability.
  • Real-time clock c/w battery back-up & daylight-savings programming.
  • Data logging including total transfers to generator, total utility power failures, load on utility hours, load on generator hours and utility or generator voltage/frequency data at time of fault.
  • Eight user Programmable Output Contacts rated 2A, 120/240V resistive, Form C. Each output contact is user programmable to 20 different functions including: Load on Utility, Load on Gen, Load Disconnect Contact (LDC), Fail to Transfer (FTT), Utility Power Available (UPA), Generator Power Available (GPA), Utility Power Fail, Engine start, ATS Not in Auto, and ATS in Auto. The Transfer Switch is pre-programmed with the following outputs enabled: Load on Utility, Load on Gen, Load Disconnect Contact (LDC), Fail to Transfer (FTT), and ATS Not in Auto.
  • Local utility power fail simulation test.
  • Remote utility power fail simulation test push-button input.
  • Local plant exercise initiate pushbutton control.
  • Engine start contact (7A, 120/240VAC resistive max.).
  • Transfer fail/forced transfer logic.
  • Automatic force transfer to alternate supply should load voltage become de-energized.
  • 50 or 60Hz capable (115V 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 16 Digital Input-voltage free input).
  • ATS Load Bus Power Metering Capability (Amp, Volt, Freq, kW, kVA, PF) with optional current transformer kit (see below).
  • RS232 Modbus Remote Communication Port (Modbus Serial RTU) via GHC.
  • USB Communication Port (Quantity 3 via GHC).
  • Serviceable Plug-in Connectors.
  • Event Logging (Time/Date Stamping).


TS870 Brochure

TS870 Manual

TS870 TSC900 Controller Brochure

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.
  • In open transition mode, the open transition delay time is adjustable, and can be set to fast transfer mode similar to Power Contactor ATS.
  • Closed Transition Mode can be bypassed to Open Transition Mode within the TSC 900 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.
  • Allows optional use of integral over current trip elements within the power switching units thus eliminating the need for external, upstream protective devices.

DUAL SOURCE OPTION (Call for Pricing)

  • Employs two mechanically interlocked power switching units with a microprocessor based controller to automatically control two sources of power such as dual utility feeders or dual prime operating generator sets.
  • Automatically transfers load to alternate source when preferred source fails.
  • Automatically re-transfers load back to preferred operating source following restoration of the power source to within normal operating limits.
  • All load transfer sequences are “Open Transition” (i.e. “break-before-make”) with adjustable neutral position delay. (Closed Transition option also available.)
  • Dual Source is available in 3 different configurations: DU- Dual Utility Sources, DSG- Dual Standby Generator (Slave ATS), and DPG- Dual Prime Generator (Prime Power)
  • Specifically designed and certified to CSA 178 and UL 1008 Standards.
  • Allows optional use of integral over current trip elements within the power switching units thus eliminating the need for external, upstream protective devices.

MORE OPTIONS (Call for Pricing)


  • 4 Poles
  • Other Three Phase Voltages (3 or 4 Wire)


  • AUX-BG – Generator Bypass Auxiliary Contact
  • AUX-BU – Utility Bypass Auxiliary Contact
  • KOTS – Key Operated Test Switch- Auto/Off/Engine Start/Test
  • PPR-10 – Programmable Power Relay Includes 10A Form C Contact Wired to Terminal Block (Up to Qty 3)
  • 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)


  • RA900-7 – 7″ Touch-screen Remote Annunciator
  • EAP1601 – Transfer to Emergency Annunciator, Alarm Horn & Silence Push-button
  • EMB-TCP/IP – Ethernet ModbusTM Remote Communication Port (ModbusTM TCP) via GHC
  • RS485A – RS 232 to RS 485 Remote Communication Adapter
  • WF-USB – WIFI USB Stick


  • Other Enclosures: NEMA 4X Stainless Steel, and NEMA 12
  • GHC-SS – Sunshade for GHC Screen
  • 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)


  • LPM – Transfer Switch Load Power Metering CT Kit (Amp, Volt, Freq, kW, kVA, PF) **Requires CT Kit
  • CTK – Current Transformer Kit
  • 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 Soft Load CT applications or even Momentary CT applications. Please inquire for other makes and models.)


  • 24DCC – 24 Volt DC-DC Converter, Regulated
  • 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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