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Specifying a DC Choke

by J.A. Edwards - Engineer

Express Transformers manufactures D.C.Chokes to Customers Requirements but to ensure the most economical design, the following parameteres should be specified:

  1. Inductance and Tolerance
  2. Nominal DC Current
  3. Thermal Rating (RMS Current)
  4. Overload
  5. Permissable roll-off at overload
  6. Ripple Frequency
  7. Ripple Amplitude
  8. Insulation Class and Maximum Temperature Rise
  9. Maximum System Voltage for insulation purposes.

 

Explanation of Roll-off

Typical Characteristic:

The most economical design is one that uses the smallest gap that will withstand the D.C. magnetisation without saturation. Often some saturation and hence a lower inductance is permissable at overload levels and this can be catered for in the design.

The Ripple Frequency if not specified will be assumed to be 300Hz.

The Ripple Amplitude if not specified will be assumed to be insignificant.

Insulation Classes from Class A(105øC) through to Class H(180øC) are available.
For further details or literature please contact

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