1) Due to the influence of output internal resistance (30, 100), when the primary inductance is too
small, the distributed voltage signal is small and the transformer gets weak energy. As the test
cable and relay will attenuate some energy, the stability and the accuracy of test will be
affected.
2) If the primary signal is enlarged, the secondary winding of the winding with more turns will
generate higher voltage which may beyond the acceptable range thus affecting the test
accuracy.
3) If the winding group with more turns is put in primary class, then the transformer can get
higher energy thus the two problems above can be avoided.
6.1.3 Transformer leakage inductance test
When use the circuit discussed in last section to make automatic sweep test on the leakage
inductance of primary inductance L1, the instrument will automatically use the relay to short the
secondary winding of the transformer so as to test the leakage inductance. From transformer
secondary winding to inner relay, the magnetic leakage is existed inevitably, so there is error of
leakage inductance in this zone. If user wants to obtain an accurate leakage value, please short the
secondary winding of the transformer based on the figure below.
SEC+
SEC-
Hc
Hp
Lp
Lc
L1
Short
TH2818
6.1.4 Capacitance test between windings of transformer
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