What Are Power Transformers And How Are They Tested - Miracle Electronics

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A transformer is a static device that transforms
electrical energy from one alternating current
to another without any change in the frequency.
Simultaneously, with the increase or decrease in
current, the voltage is also altered from high to
low or low to high. Increased voltage means it
is stepped up, and a decreased voltage means it
is stepped down. Any electrical transformers
work on the basic principle that when the primary
coil is connected to the alternating current
supply, current flows through it and an
alternating flux is set up in the core, which is
mostly linked with the secondary coil.
What are Power Transformers? Power transformers
have a rating of about 20KVA, used in generating
stations and substations at each power
transmission line for stepping the voltage up or
down. Power transformers in India are available
as single or three phases, which you can get at
Miracle Electronics at the best quality and
rates. Power transformers are used during heavy
load periods, and are disconnected during light
load periods. This is why they are designed to
have maximum efficiency and greater leakage
resistance at full load.
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• There are certain important facts that are
  standard to any transformer
• At no load, the primary applied voltage is
  balanced by the secondary in an ideal
  transformer.
• The induced electromagnetic force in the
  secondary winding of a transformer depends upon
  the frequency, flux, and number of turns in the
  secondary.
• The magnitude of flux in a transformer is same at
  all levels.
• How Are Transformers Tested?
• Every transformer must be tested before use. In
  fact, every manufacturer must test their
  transformers before supplying them to their
  clients. Reputed manufacturers like Miracle
  Electronics always supply the finest power
  transformers in India that are always tested
  after being manufactured to check for any flaws
  and errors that can be rectified before supplying
  them into the market. There are two types of
  tests that should be performed on a transformer
• open circuit test and short circuit test
  which can determine the parameter or constants of
  the transformer, efficiency, and regulation. Let
  us learn about these tests in detail.
• OPEN CIRCUIT TEST This test determines the iron
  losses and no load current of the transformer.
  To perform this test, the winding with the lower
  voltage is connected to the normal supply with
  an ammeter to measure the voltage applied to the
  winding, and to a wattmeter to measure the
  voltage at no load. The winding with the higher
  voltage is kept open. This set up will create
  flux in the core, leading to iron losses, which
  will be indicated by the wattmeter.
• SHORT CIRCUIT TEST This test determines the
  copper losses at full load, and the equivalent
  resistance and reactance. To perform this test, a
  reduced value of the voltage is increased on the
  winding with the higher voltage until full load
  current flows. This produces is a relatively
  smaller flux, which is why the core losses can be
  neglected. The wattmeter used in this test
  indicates the total copper losses.
• For more information visit Miracle Electronics