7.11.2.1 Turn Mode
When touching the TURN setting area or moving the cursor to the TURN setting area, the TURN
mode can be set in the menu on the right.
TH2840X test TURN can choose the following 8 modes:
TURN_v= primary standard value * secondary voltage/ primary voltage. This mode is
used test transformer turn number.
TURN = primary standard value * secondary turn/ primary turn. When the primary
inductance is small, using this mode can test the turn number more accurately. But, when
testing magnetic core with high magnetic conductivity, in such mode, the data will be unstable
due to the polarized magnetic core.
VOLT = Primary test voltage * secondary voltage / primary voltage
Vs:Vp = Secondary voltage/ primary voltage
Ns:Np = Secondary turn/ primary turn
TURN_L= Inductance ratio mode
Np:Ns = Primary turn/ secondary turn
Lp:Ls = Primary inductance/ secondary inductance
It is recommended to put the windings with multi-turns in the primary turn ratio, the reasons are as
follows:
1. By the influence of output internal resistance (30, 100), when the primary inductance is
small, the distributed voltage signal will also be small and the energy the transformer gets is
also weak. The test cable and the relay will attenuate a part of energy, so the stability and
accuracy will be affected.
2. If the primary signal is forced to be enlarged, then the voltage generated by secondary
multi-winding will be high and it may be over the range of the instrument and thus further
affect the test accuracy.
3. If the winding with multi-turns is put in primary test, then the energy of the transformer
will be strong and above 2 problems can be ignored.
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