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What is a Primary Winding?

The primary winding is the winding on the energy input (supply) side.

  • What does radial-feed mean?
  • What does loop-feed mean?
  • What does the dot mean on a single phase transformer wiring schematic?

      Typically, a single phase transformer wiring schematic has a dot on both the primary and secondary windings.

      The placement of these dots next to the ends of the primary and secondary windings informs us that the instantaneous voltage polarity seen across the primary winding will be the same across the secondary winding. In other words, the phase shift from primary to secondary will be zero degrees, which is important for some types of circuits. If the wiring to the dots is reversed on one side, the primary and secondary will be 180 degrees out of phase.

  • Why do Buck-Boost transformers have 4 windings?

      A four winding buck-boost transformer with 2 primary and 2 secondary windings can be connected eight different ways to provide a multitude of voltages and kVA’s. This provides the flexibility necessary for the broad variety of applications. A two-winding transformer can only be connected in two different ways.

  • What is a “Dual Winding”?

      A winding consisting of two separate parts which can be connected in series or parallel. Also referred to as dual voltage or series-multiple winding.

  • What makes up a Coil?
  • What is Temperature Rise?
  • What is an “Electrostatic Shield”?

      Electrostatically shielded (Faraday Shield) transformers provides a copper electrostatic shield between the primary and secondary windings. The shield is grounded and thus shunts some noise and transients to the ground path rather than passing them through to the secondary. Transformers having a K-Rating are required to have an electrostatic shield.

      Electrostatically shielded transformers often preferred for electrical installations where electronic circuitry operating at low voltage DC is present and is very sensitive to ‘noise’. Recent testing of electrostatically shielded transformers has questioned their perceived effectiveness where the transformer’s secondary is grounded which would cover most applications.

  • What is IR drop

      IR drops relates to Ohm’s Law: Voltage = Current x Resistance. Transformers utilize conductors which have resistance and can cause a slight voltage drop. Typically manufacturers compensate the winding ratio to mitigate any effects of IR voltage drop in the secondary voltage.

  • What is a triplex transformer?

      A triplex transformer is composed of three separate single phase transformers which are banked and connected directly together to form a single three phase unit in a common enclosure. While slightly larger than a dedicated three phase unit. a triplex design can be broken down into three significantly smaller and lighter components when there are size and/or weight restrictions for transporting the transformer. These are often used in mining or high rise building installations where the unit must be transported in an elevator.

  • What are Electrostically Shielded Transformers and where are they used?

      Electrostatically shielded (Faraday Shield) transformers provides a copper electrostatic shield between the primary and secondary windings. The shield is grounded and thus shunts some noise and transients to the ground path rather than passing them through to the secondary. Transformers having a K-Rating are required to have an electrostatic shield.

      Electrostatically shielded transformers often preferred for electrical installations where electronic circuitry operating at low voltage DC is present and is very sensitive to ‘noise’. Recent testing of electrostatically shielded transformers has questioned their perceived effectiveness where the transformer’s secondary is grounded which would cover most applications.

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  • How to transformer taps adjust voltage?

      The ratio between the number of windings in the primary and secondary coil’s of a transformer determines the voltage ratio. If a transformer has 100 primary windings and 25 secondary windings, the ratio is 100:25 = 4:1. If the primary is fed with 480VAC, the ratio of primary to secondary voltage is 4:1 or 480:120. Taps are used to adjust for voltage differences at the transformer’s primary winding.A 5% adds or subtracts 5% of the windings.

  • What is a Secondary Winding?
  • What is a Primary Winding?
  • Define Series/Multiple?

      A winding consisting of two or more sections which can be connected for series operation or multiple (parallel) operation. Also referred to as dual voltage or series-parallel.

  • What is a dual output Harmonic Mitigating Transformer

      Like a standard HMT, a dual put HMT minimizes the voltage distortion rise due to the transformer itself. Harmonic Mitigating Transformers (HMTs) are designed to reduce the impedance seen by the harmonic currents. This is accomplished through zero sequence flux cancellation and through phase shifting. The secondary winding configuration of the HMT cancels the zero sequence fluxes; those produced by the 3rd, 9th, 15th (triplen) current harmonics, without coupling them to the primary windings.

      This prevents the triplen current harmonics from circulating in the primary windings as they do in a delta-wye transformer. The flux cancellation also results in much lower impedance to the zero sequence currents and hence lower voltage distortion at these harmonics. In addition, the reduced primary winding circulating current will lower losses and allow the transformer to run cooler.

      More Harmonic Mitigating Transformer Frequently Asked Questions