Ls Or Lp - Inductance (Series Or Parallel Circuit) - Voltech AT5600 User Manual

C H A P T E R 7 – T E S T S
7.7.

LS or LP - Inductance (Series or Parallel Circuit)

Where Used
The AT5600 provides two primary methods to verify that a transformer has been
assembled correctly: ensuring the proper number of primary and secondary turns,
using the correct magnetic core material, and setting the appropriate air gap if
required.
Any real inductor can be represented as either an equivalent series RL circuit or a
parallel RL circuit.
In an Ideal inductor Rs=0, Rp=infinity, hence LS=LP,
However, in real inductors, the inductance values for series and parallel circuits
may differ, which should be considered when specifying test limits.
Inductance is always measured as part of the complex impedance and is
expressed in terms of a series or parallel equivalent circuit, depending on whether
you choose the LS or LP test.
For signal, pulse, and switched-mode power transformers, where small
excursions of the B-H curve are typical (remaining within the linear regions), a
primary inductance measurement along with a Turns Ratio test is recommended.
For line frequency transformers, which operate across the full B-H curve,
including non-linear regions, the preferred approach is to conduct a magnetizing
current test on the primary winding, followed by an open-circuit voltage test on the
remaining windings.
AT5600 User Manual 98-119 issue 30
A N D T E S T C O N D I T I O N S
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