Voltech AT5600 User Manual page 125

C H A P T E R 7 – T E S T S
Current levels
For larger capacitances, particularly at higher frequencies, the current flowing
during the measurement can be very high, and similarly the measured current
could also be very small for small capacitances at lower frequencies and voltages.
Where possible, you should use the recommended test signal levels in the table
above to ensure that the currents which flow can be measured accurately.
Non-linear Capacitance
Normally non-linearity in the stray capacitance of transformers are not a problem,
and therefore capacitance is measured with as large a voltage as possible.
Equivalent Circuit
As with inductance, capacitance is measured as a complex impedance, and
therefore the result can be expressed in terms of either a series or a parallel
equivalent circuit.
It was explained in section 7.7, that parallel and series equivalent inductance do
not necessarily have the same values. The same is true for capacitance; parallel
and series equivalents can also be different.
The tester uses a parallel equivalent circuit for capacitance measurements and
does not give you a choice of a series equivalent.
Generally, this will present no problems, as on most transformers the difference
between the two values is usually negligible and can be ignored.
Please also see
14.6.14 for specific advice on programming the test, and
10.2.18 for test accuracy specification
AT5600 User Manual 98-119 issue 14
A N D T E S T C O N D I T I O N S
Page 125