ESI 250-DA - Considerations for Inductor Measurements

2.3.3
THINGS
TO
WATCH
OUT
FOR
2.
3.
3.
1
LOW
INDUCTANCE
MEASUREMENTS
The
bridge
measures
the
total
impedance
connected
to
its
terminals.
Both
the
unknown
inductor
and
its
leads
contribute
to
this
impedance.
The
leads
have
some
resistance
and
inductance,
which
affect
the
value
read
from the
bridge
.
Z
-
Impedance
of
unknown
inductor
Z
L
Impedance
of
leads
For
greatest
accuracy,
minimize
the
lead
impedance.
Short heavy
leads
will
reduce
the
resistance.
Closely
spaced
twisted
leads
will reduce the
inductance
and
the
pickup
of
stray
fields.
2.
3. 3.
2
HIGH
INDUCTANCE
MEASUREMENTS
In
making
high
inductance
measurements,
there
are
two
things
to
watch
out
for:
1.
Be
careful
to
avoid
hum
pickup.
2,
Keep
the
stray
capacitance
to a
minimum.
To
minimize
both
effects
keep
your
hands
as
far
as
possible
from the
inductor
measured.
Keep
the
leads
as
short
and
direct as
possible. If
extended leads are
necessary,
the
lead
from
the LO
terminal
should be shielded.
See
section
2.4.6
"Extended
Leads".
Care
should
be
taken
to
avoid
coupling
stray
magnetic
fields
into
the in-
ductor
being
measured.
The D
and
Q
readings
on
the
highest
L
range
will
be in
error as
indicated in
the
specifications
because
of
the
residual
capacitance
of
the
range
resistor.
If
accurate
D
or
Q
readings
are
needed
the
next
lowest
L
range can
be used.
The L
readings
on
the
high
range
are
accurate.
lelsl
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250-DA
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