I have a transformer schematic above.
I'm using a Micro ohms meter to measure DCR of winding (1-2), however the measurement is not stable and fluctuating.
So i shorted out pin 3-4 on the secondary winding, then i have a stabilized reading of winding (1-2).
and vice versa when measure DCR for winding (3-4).
May any body explain about this phenomena? Why does it occur?
Is my measurement method valid and acceptable?
Thanks

 

Simplistic explanation:
Any magnetic fluctuation you are causing by measuring with the other winding open is reflected in the winding, by shorting the opposing coil, this essentially is a magnetic short or damping of any fluctuation that may occur.

 

Simplistic explanation:
Any magnetic fluctuation you are causing by measuring with the other winding open is reflected in the winding, by shorting the opposing coil, this essentially is a magnetic short or damping of any fluctuation that may occur.

Thank you for explanation!!!

 

Is my measurement method valid and acceptable

What was the result of your measurements.
Did the DC winding resistance value of the primary match the secondary?

 

I have seen this effect when using an auto ranging ohm meter. As the meter changes it's range it changes the test current. This change in current though the inductor causes a a change in voltage which confuses the meter which then keeps jumping between ranges. This is not quite the same as the TS's situation as the micro ohm meter is not likely to be auto ranging.

Les.

 

An auto-ranging meter may have a function to hold a measurement range and not auto-range. If this is available on your meter then use this which should stop the 'bouncing' if auto-range is the problem.

 

What was the result of your measurements.
Did the DC winding resistance value of the primary match the secondary?

yes. they match