C H A P T E R 7 – T E S T S A N D T E S T C O N D I T I O N S
AT5600 User Manual 98-119 issue 14 Page 98
7.5. R - Winding Resistance
Where Used
The measurement of the resistance of all windings should generally be the first
group of tests carried out for any type of transformer. It checks that the wire is of
the correct diameter and has not been over-tensioned during winding.
The measurement also confirms that the connections between the test fixture and
the transformer have been made properly. This is particularly important when
Kelvin connections are required, perhaps for a test to follow, as a resistance
measurement will confirm that both the power lead and sense lead are making
good electrical contact.
To check if the resistance of a winding is correct, the tester applies a constant
current (DC) to the selected winding. Both the current through and the voltage
across the winding are measured; dividing the voltage by the current gives the
value of the resistance.
Specifying the Test Limits
Maximum Value - Specify limit as tightly as possible to ensure that correct wire
has been used.
Minimum Value - Not usually so critical - can be set to any value that ensures
that there is no solder splash causing a short circuit between
pins.
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