Voltech AT5600 User Manual page 113

C H A P T E R 7 – T E S T S
Inductance of the
Energized Winding
100nH →
1uH →
10uH
→
100uH
→
1mH
→
10mH
→
100mH
→
1H
→
10H
→
100H
→
1KH
→
Notes: The signal is applied to the primary winding, or the winding which has the
largest number of turns.
However, if by doing this, the expected voltage on the winding with the
smallest number of turns falls below 1mV, then the test voltage should be
increased.
This may also require an increase in the test frequency so that the current
taken by the driven winding does not become too large, but in general this
frequency increase should be kept as small as possible to avoid problems
caused by stray capacitance at high frequencies.
Where Matching in Groups is Important
In some transformer designs, the turns ratio between a primary winding and a
secondary winding is not as important as the ratio between different primaries or
different secondary's.
To make the most accurate measurements in such cases apply the test signal to
the primary winding and measure the turns-ratio from primary to one of the
secondary's.
Then, leaving the primary energized as above, measure the turns ratio between
the secondary's.
Next, energize a secondary winding (possibly at a different voltage and / or
frequency depending on its inductance) and measure the turns ratio between the
various primaries.
In this way windings, which should be matched are treated equally during the test.
AT5600 User Manual 98-119 issue 14
A N D T E S T C O N D I T I O N S
Table 4
1uH
10uH
100uH
1mH
10mH
100mH
1H
10H
100H
1KH
10KH
The Test Conditions for Turns Ratio Measurement
Preferred test signal
Frequency
300KHz 10mV
100KHz 30mV
30KHz 50mV
10KHz 100mV
1KHz 100mV
100Hz 100mV
100Hz 300mV
50Hz 1V
50Hz 5V
50Hz 5V
20Hz 5V
Voltage
Page 113