US 4,573,012 AGranted

Method and apparatus for measuring core loss of a laminated ferromagnetic structure

AssigneeGeneral Electric Company

InventorsDonald K. Bisson, Steven A. Nardin

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Abstract

A core loss tester employs separate cables for excitation and pickup. Testing is performed at a fixed flux density in the ferromagnetic core. A processing circuit on the output of the pickup coil scales the voltage developed so that, when excitation current is increased so that the indicated output of the pickup coil equals the effective cross-sectional area of the flux path, the fixed predetermined value of flux density is produced. When this condition is achieved, the excitation current times the sensed flux-induced voltage provides a measurement of the core loss in watts. Excitation is accomplished with a multi-conductor cable looped once or more times through the core with the conductors in the cable connected in series by mating together of a connector at each end.

Claims10

Dependent claims

A tester for measuring electrical losses in a flux path of a ferromagnetic structure, said flux path having a predetermined cross-sectional area, comprising:

a first coil for coupling to said structure;
means connectable to said first coil for driving an alternating current therethrough whereby a magnetic flux is produced in said flux path;
a second coil for coupling to said structure and for producing a flux signal in response to said magnetic flux in said flux path;
means connectable to said second coil for scaling said flux signal to produce a voltage related to a fixed value of flux density in said flux path and said predetermined cross-sectional area;
first means connected with said scaling means for indicating said voltage scaled in units of area;
means responsive to said alternating current for developing a first signal indicative of the amplitude thereof;
means responsive to said flux signal for developing a second signal indicative of the magnitude thereof;
means responsive to said first and second signals for multiplying said first signal by said second signal to produce a power loss signal;
second means responsive to said power loss signal for indicating the power loss in said ferromagnetic structure;
and
means for adjusting said alternating current driving means to vary the amplitude of said alternating current until said first indicating means produces an indication equal to said predetermined cross-sectional area, whereby a condition for reading the power loss indication on said second indicating means is produced.

8 more elements

A core loss tester for testing power loss in a flux path in a core, comprising:

a first coil for making at least one turn about said core;
a second coil for making at least one turn about said core spaced from said first coil;
a variable transformer connectable to said first coil for applying an alternating current thereto;
first means responsive to said alternating current for producing a current signal indicative of the magnitude thereof;
second means connectable with said second coil for producing a flux signal responsive to a magnetic flux in said core encircled by said at least one turn of said second coil;
a multiplier connected to said first and second means for multiplying said current signal by said flux signal to produce a core loss signal;
an absolute value circuit connected to said second means and effective to produce a DC signal proportional to an average of an absolute value of said flux signal;
and
a voltage divider connected to said absolute value circuit and effective to scale said DC signal to provide an output voltage having a predetermined magnitude per unit of cross-sectional area of said flux path when a fixed predetermined flux density exists in said flux path as established by adjustment of said variable transformer.

6 more elements

Dependencies are inferred from the claim text.