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The ferroresonant transformer, ferroresonant regulator or constant-voltage transformer is a type of saturating transformer used as a voltage regulator. These transformers use a tank circuit composed of a high-voltage resonant winding and a capacitor to produce a nearly constant average output voltage with a varying input current or varying load.
An inductive load is used to simulate a real-life mixed commercial loads consisting of lighting, heating, motors, transformers, etc. With a resistive-inductive load bank, full power system testing is possible, because the provided impedance supplies currents out of phase with voltage and allows for performance evaluation of generators, voltage ...
A 120:120 instrument isolation transformer showing two polarity marking conventions. Voltage transformers (VT), also called potential transformers (PT), are a parallel-connected type of instrument transformer. They are designed to present a negligible load to the supply being measured and have an accurate voltage ratio and phase relationship to ...
Other advantages of autotransformers include lower leakage reactance, lower losses, lower excitation current, and increased VA rating for a given size and mass. [ 2 ] An example of an application of an autotransformer is one style of traveler's voltage converter , that allows 230-volt devices to be used on 120-volt supply circuits, or the reverse.
Pad-mounted transformers are made in power ratings from around 15 to around 5000 kVA and often include built-in fuses and switches. Primary power cables may be connected with elbow connectors, which can be operated when energized using a hot stick and allows for flexibility in repair and maintenance.
The oil is cooled by the outside of the tank in small ratings, and by an air-cooled radiator in larger ratings. Where a higher rating is required, or where the transformer is in a building or underground, oil pumps circulate the oil, fans may force air over the radiators, or an oil-to-water heat exchanger may also be used. [9]
Distribution transformers typically have ratings less than 200 kVA, [3] although some national standards allow units up to 5000 kVA to be described as distribution transformers. Since distribution transformers are energized 24 hours a day (even when they don't carry any load), reducing iron losses is vital in their design. They usually don't ...
For example, helicopter engines are rated for continuous power (which does not have a time constraint), takeoff and hover power rating (defined as half to one-hour operation), maximum contingency power (which can be sustained for two-three minutes), and emergency (half a minute) power rating. [9] For electrical motors, a similar kind of ...