[Amps] Testing swinging chokes

[Bob]

Hi to the group,
                                There is only one "good" way of testing a
"swinging" choke. It needs a reasonable two channel digital storage scope. A
bank of electrolytic caps and DC power supply for "say" 20 volts with a
current limit, a good sized thyristor or heavy duty switch or relay and a
current measuring device ( a suitable shunt or LEM/hall effect device.)
 
What you are going to do is to connect the choke across a DC supply via the
switch or thyristor and measure the voltage across the choke (while the caps
discharge) and also measure the current flowing through the choke at the
same time. The slope of the rising of current together with the voltage at
that instant allows you to calculate the actual DC inductance at any point
on the curve. E(voltage across the inductor) = - L di/dt(slope of current
trace).
 
I've used this method for many years over a very wide range of choke sizes
and current ratings. The choice of supply voltage depends on the DC
resistance of the choke and should be such that you get ~10 X the current
that you are interested in if you divide the resistance of the choke into
the supply voltage.
 
Regards Bob ZS6 BXI

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