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Rack-Mounted Automatic Transfer Switches

TwinSource Rack-Mounted Automatic Transfer Switches Provide the Highest Reliability of Electrical Supply at 7×24 Mission Critical Facilities For Protection of Single Cord, Dual Cord, and Triple Cord Electronic Loads

Automatic transfer switches in both solid state (single phase and three phase) and electromechanical (single phase) versions.

The TwinSource Rack Mount Static Transfer Switch is considered “Best in Class” among rackmounted automatic transfer switch products. It has a proven track record of over 60,000,000 hours on line without a load failure among its installed base worldwide. We have systems across the globe mostly populated in US, UK, Singapore, Korea, Hong Kong, Dubai, and other locations. For more information on the products please refer to the corresponding tabs above. This web site also offers a general tutorial on all ratings and types of transfer switches which you will find very informative.




For Highly Mission Critical Applications Where The Cost Of Each Outage Is Substantial

Rack-Mount Automatic Static Transfer Switch (RMSTS)

The patented MagLatch™ design makes use of dual coil magnetically latched relays, rather than standard single coil relays, to eliminate contact bounce and relay failures caused by their coils remaining continuously energized. Coils that remain energized can experience winding failures due to heat if they remain on for too long which is what happens in ATSs when they transfer or if the alternate source is selected as preferred. The dual coil feature enables fast electrically forced transfers in both directions vs. only in one direction. 

  • Super Fast (1/4 cycle) SCR Based Static Transfer Switch for high availability mission critical applications with a high fault (22KA) rating that is certified to UL1008 Standards.
  • Transfers for all phase angle differences between sources.
  • MTBF > 60 million hours.
  • Continuous Duty 100% rated (i.e., a 30A switch is rated for 30A continuous and not just 24A at 80%).
  • TUV Certified to UL1008 and CSA for Static Transfer Switch Standards. CE Labeled for international use.

Features & Benefits

  • 4U high construction with a Plug-in Electronic Module (EM) that plugs into an outer Built-in Bypass Isolation
  • Module (BM) with a 7 Position Bypass Isolation Selector.
  • Built-in Voltage Suppression & Transient Protection to protect internal electronics.
  • Completely user settable and configurable.
  • Two isolated voltage-free summary alarm contacts.
  • Optional Modbus RTU RS 485 Interface to connect to your Building Management System (BMS) for monitoring of all status and alarms.
  • Optional Ethernet Translator Unit (ETU) for stand alone LAN/Web based monitoring of all status and alarms – can acknowledge alarms and records and archives data, allows remote preferred source selection, reports power quality at all racks for both sources, allows for independent monitoring and archiving away from the BMS if monitoring by the BMS is excessively costly.
  • Optional Interlocks to prevent removal of the Electronic Module before Bypass Selector is in bypass isolate position and to not allow movement of selector if the EM has not been placed back into the unit after a maintenance action.
For Less Critical Applications Where Cost Is A Major Consideration

Rack-Mount Automatic Static Transfer Switch (RMSTS)

The TwinSource MagLatch™ RMATSs are a cost effective way to convert single corded IT loads to dual corded configuration so as to achieve the same availability as the dual corded loads.

Features & Benefits

  • Fast Transfer (1/2 to 1 cycle for in-phase sources) electromechanical design as a cost effective solution for a basic transfer switch, rated at 22KA with upstream protective devices.
  • Transfers for all phase angle differences between sources.
    MTBF > 500,000 hours.
  • Continuous Duty 100% rated at 24A.
  • Certified to meet UL-IEC 60950 Standards for both domestic and international use.
  • 1U high construction (without bypass).
  • Completely user set table and configurable.
  • Standard Remote Contacts as well as Optional Mod bus RTU RS 485 Interface to connect to your Building Management System (BMS) for monitoring of all status and alarms.
  • Optional Analogue Values Readings: V, A, KW, KVA, pf, f.
  • Optional Waveform Capture – captures the waveform of the last transfer for diagnostic purposes and eliminates the need for costly rental of monitoring equipment in each rack.

Packaged Mini-2N And Mini-4N UPS/RMSTS Systems

Ideal if you don’t want to intrude into your already installed large 2N system on site or if you need protection for a smaller server room with some single cord loads. You can also use this as a standard packaged solution for all your data centers that have single corded loads. The 2N UPSs are 80KVA, 480V, 3ph, 3W + G In, 480V, 3ph, 3W + G Out and sit on each side of a lineup of 2 outer UPS Modules (and typically 10 min. batteries) and the inner enclosures that contain the step down (from 480 to 208/120) Input Sections A and B, the STS Section, and the Output Section.


Features & Benefits

Mini-4N System (2 Sets Of Mini-2N’s Connected To The Same Dual Cord Loads)

Each cord is supported by a separate 2N. The description of the Mini-4N is exactly the same as one Mini-2N x 2 sets with UPS designations A, B, C, and D in a paired fashion (A & B + C & D). Each dual corded load gets a feed from Mini 2N 1 and another Mini-2N 2.


  • A multinational bank operations center performing critical 7 x 24 operations cannot sustain an outage without substantial losses and disruption to global operations.
  • A telecommunications site that hosts multitudes of users cannot go down without loss of revenues and credibility with its customers.
  • A boiler control system of a power plant supporting a major manufacturing operation cannot be disabled without substantial cost of recovery and degradation of product quality.
  • Loss of power to computers and display systems at a major air traffic control center poses risks to passenger safety as well as causing flight delays.
  • Loss of power to systems controlling tools, ovens, and apparatus that manufacture intricate microelectronics can cause lost product, delays in shipment, and loss of quality.
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