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Type QB – Buck Boost

ABB LV Dry Type Encapsulated Enclosed Transformers

Buck-boost transformers are small, single phase, dry type distribution transformers designed and shipped as insulating/isolating transformers. They have a dual voltage primary and a dual voltage secondary. These transformers can be connected for a wide range of voltage combinations. The most common use is to buck (lower) or boost (raise) the supply voltage a small amount, usually 5 to 27%. Buck boost transformers comply with NEC Article 210-9, Exception 1, when field connected as an autotransformer.

Features and benefits

  • Efficient insulating materials permit compact size and light weight
  • Dual voltage primary and dual voltage secondary for maximum versatility
  • Large, front-accessible wiring compartment permits fast, easy wiring
  • Convenient conduit knockouts located on side, bottom and back of wiring compartment
  • Indoor or outdoor service
  • Convenient method of matching line voltage with equipment voltage
  • Ability to handle loads up to 20 times nameplate rating when connected as an autotransformer
  • Ideal for changing line voltages by small amounts
  • Primary voltages include 120V, 240V and 480V
  • Secondary voltages include 12V, 16V, 24V, 32V, 48V
  • UL and cUL Listed
  • Qualified to the seismic requirements of IEEE-693-1997 and IBC-2003


  • International voltage adaptation
  • Commercial and industrial air conditioning
  • Heating systems
  • Induction motors
  • Voltage line drop correction
  • Landscape lighting
  • Low-voltage lighting