Variable Toroidal Transformers, 10-300 kVA

Overview

Transformateurs toroïdaux variables, 10-300 kVA are autotransformers that provide a continuously adjustable output voltage for input line voltages from 120 to 600 Volts AC. The product description states an output voltage expressed as a percentage of input in ranges of 0 to 100 % or 0 to 117 %, and the electrical characteristics list an output capability of 0 to 17 % above line voltage. The windings are copper with a toroidal core forming a toroidal helix, with the outer face of the windings exposed to provide a current-collection path; a carbon brush traverses the windings via an output-voltage selector (oscillator) that starts at the center of the torus and rotates up to a maximum of 318 degrees around the transformer face, producing an output voltage that varies linearly with oscillator rotation angle. Multiple transformers can be stacked on a common shaft and wired in series and/or parallel to double line voltage and increase current and rated kVA. Configurations are available in single-phase and three-phase, with motorized and manual units offered; motorized units use chain and sprockets to change oscillator speed relative to motor speed and include limit switches at upper and lower winding limits, and DC motors can be used for a variable rise rate. Additional electrical and mechanical details include individual cooling fans, an overload capacity of 250 % for 2 minutes, a wiring diagram located on the terminal plate, lifting points for crane handling, optional IP21 enclosures defined to IEC 529, enclosure construction in heavy-gauge steel with durable polyurethane-based paint, and a base on steel skids for forklift movement. The product is described as a versatile power source. For low kVA applications, TOVT assemblies can be operated manually to provide precise voltage control. To automate control and obtain larger powers, a motorized drive is required; motorized units can adjust oscillator speed via chain and sprockets to change rise time, and DC motors can provide a variable rise rate. Stacking multiple transformers on a common shaft and wiring them in series and/or parallel is an intended method to double line voltage and increase current and rated kVA.