2.3.3 Inductance Measurements
The 252 measures the total impedance connected to its terminals. Both the unknown inductor and it’s
leads contribute to this impedance. The leads have some resistance and inductance which affect
the value read from the meter.
In making high inductance measurements, avoid AC pickup and keep the stray capacitance to a
minimum. To minimize both effects, keep hands as far as possible from the inductor being measured.
Keep the leads as short and direct as possible. Take care to avoid coupling stray magnetic fields
into the inductor.
For greatest accuracy on low inductance measurements, minimize the lead impedance. Closely
spaced, twisted leads will reduce the inductance and pickup of stray fields. The KELVIN KLIPS®
Cable Assembly will add about 0.5µH to Ls and 0mΩ to Rs. Short the test leads together and
subtract the reading from the unknown inductance measured.
Measuring leakage inductance of transformer windings is an easy task for the Model 252 since
there are no “false nulls” as found in manually-balanced bridges.
2-18
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