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Product Status Discontinued on 2/2/2023

SmartOnline S3MT-Series 3-Phase 20kVA Input Isolation Transformer, Delta 480V to 208V Wye, TAA

Part Number:  S3MT-20K480V

S3MT-20K480V product image


Get Complete Step-Down and Isolation Protection and Prevent Power Disruption
Tripp Lite’s S3MT-20K480V 20kVA/kW transformer offers line isolation and protection to the connected 3-phase UPS system and its load. It isolates the UPS and connected components from line surges and spikes caused by utility power disruptions that can damage equipment or corrupt data. The step-down input isolation transformer is ideal for 4-wire (3Ph+N+PE) IT loads in government, manufacturing, healthcare and corporate settings with a 480V electrical feed and 208/120V equipment.

Performs with High Efficiency up to 96.5%
Not only is the S3MT-20K480V very efficient, with up to 96.5 percent efficiency, but it is also very quiet with a noise profile less than 65 dBA. A built-in circuit breaker on the output side helps prevent dangerous power overloads. Two ball-bearing cooling fans help prevent overheating. An overheat-sensing relay and switch combine with a red LED indicator to provide over-temperature warning and overheating protection.

Small Footprint for Quick Installation in a Compact Space
The compact footprint enables installation of the S3MT-20K480V with minimal space. The rugged stainless steel housing ships ready for immediate installation with a compatible 10–20kVA/kW Tripp Lite S3M-Series 3-phase UPS system.


Package Includes

  • S3MT-20K480V 3-Phase 20kVA Input Isolation Transformer
  • Owner’s manual
TAA compliant RoHS compliant


UPC Code037332253132
Efficiency95% @ full load
Nominal Voltage / Frequency480V 3-PH / 60Hz
VA / Watt Capacity20000
Transformer TypeDry type, Input step-down isolation transformer
Input Phase3-Phase
Nominal Input Voltage(s) Supported480V 3-PH Delta
UPS Input Connection TypeHardwire
Output Capacity (VA)20000
Output Capacity (kVA)20
Nominal Output Voltage(s) Supported120/208V 3-PH Wye
Output ReceptaclesHardwire
Primary Form FactorTower
Cooling Method2 x BALL BEARING, 120MM (288 TOTAL CFM)
Form Factors SupportedTower
Shipping Dimensions (hwd / in.)54.80 x 22.20 x 37.80
Unit Dimensions (hwd / in.)47.200 x 17.400 x 33.500
Unit Weight (lbs.)430
Heat Dissipation (BTU/Hr) @ Full Load  3413
Input Voltage480V 3-PH Delta
Input Voltage Range(-45%, +25%) for 40% load (-20%, +25%) for 100% load
Input Amp(s)35 A
AC Input ConfigurationDelta
AC Input Frequency50/60
Frequency Range40/70Hz
Voltage SelectionNONE
Input Inrush Current300 A
VA Rating20K
Input Number of Phases3PH
AC Output Voltage (V)120/208V 3-PH Wye
AC Output Amps75 A
Output Number of Phases3PH + N
AC Output ConfigurationWYE
Output IsolationYes
Output Breaker Rating80 A
LED Warning Light FunctionsThe over-temperature warning LED light will turn ON when the output/secondary of the Input transformer reaches 160°C ±5°C and will turn OFF wthen the corresponding transfomer cools down to 125°C ±5°C
Over Temperature ResetIf the secondary side of the input transformer reaches temperatures of or higher than 160°C ± 5°C, i.e. a range of 155°C to 165°C (311°F to 329°F), an over-temperature protection relay and thermal switch will activate and will open the breaker on secondary side of the transformer. Once the transformer temperature has cooled down to 125°C ± 5°C, i.e. a range of 120°C to 130°C ( 248°F to 266°F) the warning LED light will turn OFF, and you may manually re-activate (close) the output breaker on the transformer to restart normal operation.
Efficiency @ Half Load0.965
Efficiency @ Full Load0.95
Heat Dissipation (BTU/Hr) @ Full Load3413
Audible Noise (dBA @ 1m)65dB max
UPS ApplicationsMission Critical Applications
Efficiency @ Half Load0.965
Efficiency @ Full Load0.95
Product ComplianceTrade Agreements Act (TAA)
Product Warranty Period (U.S. & Canada)2-year limited warranty

Questions & Answers



  Model Number Description
20-60kVA 3-Phase Power Distribution Center SUDC208V42P SUDC208V42P 20-60kVA 3-Phase Power Distribution Center

Need help with your purchase?
We're always available to help with questions, including product selection, sizing, installation and product customization. Call us at +1 773-869-1776 or email