Hioki IM3536 - X84; How to Supply a DC Bias Current

Appx.8
Supplying DC Bias
How to supply a DC bias current
WARNING
In order to avoid electric shock accident, be absolutely sure not to touch
the test terminals while the DC bias is being supplied to them.
CAUTION
• Due to the inductance of the coil and the sample, counter electromotive force is gen-
erated when the sample is removed or inserted with the DC bias supplied. This may
result in damage to the instrument or to the DC source.
• When measuring the element whose DC resistance is high (incl. open state), a high
voltage occurred on the H side may cause damage on the main instrument.
• Use a DC current supply whose output is isolated from ground. Failure to do so could
enable DC current to ow into the instrument, damaging the instrument.
When you want to apply a DC current bias, refer to the following explanation.
With regards to a DC current bias for a transformer, choke coil, or other test sample, congure the
external bias circuit as shown below.
DC Bias Current Circuit
IM3536
Z
Measurement
sample
+
-
DC current
source
+
-
H
CUR
H
POT
R
HC
R
HP
C
HC
C
HP
Capacitor
Choke coil
CH
L
POT
L
CUR
• Connect the sample to the measuring cable, probe, or xture and then gradually raise the voltage
of the DC source to the specied DC bias level. To disconnect the sample, gradually reduce the
voltage of the DC source until the DC bias supplied to the sample is decreased to zero. You may
disconnect the sample after this is achieved.
• Use a choke coil (CH) which has a large enough impedance with reference to the sample under
test (Z).
• A H
CUR
side capacitor must have a small enough impedance (i.e. a large enough capacitance)
relative to the output resistance (100
Ω
) while a H
POT
capacitor must have a small enough imped-
ance to the R
HP
.
• Be careful about the polarity when connecting together the measurement cables, probes, or x-
ture, the sample to be tested, and the DC current source.
• Be careful not to magnetically saturate the choke coil (CH) with the DC bias current.
• It takes a little time for the DC current which is being supplied to the sample under test to reach
the set value, so you should wait for a certain stabilization time period (which depends upon the
sample) before performing testing. Be careful, because if you perform testing before this stabiliza-
tion time period has elapsed, the results will not be reliable.