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Profeesional LCR Meter / English Profeesional LCR Meter / English
Though in some cases,series mode would be preferred. For instance,measuring a large capacitor would
require using series mode for optimal reading. Otherwise,the meter may show the reading results as out of
accuracy or erroneous.Series mode is use because large capacitors often have higher dissipation factor
and lower internal resistance.
Inductance
For most inductance measurement, selecting series mode is the best. This is because in this mode, accurate
Q (quality factor) reading can be obtained from reading low Q inductors and ohmic losses are significant.
Though in some cases, parallel mode would be preferred. For example, iron core inductors operating at
higher frequencies where hysteresis and eddy currents become significant would require measurement in
parallel mode for optimal results.
7-3 Accuracy Discrepancies
In some special cases, inaccuracies may occur in the measurement of capacitive, inductive, and resistive
components.
Capacitance
When measuring capacitors,it is always most desirable if the dissipation factor is low.Electrolytic capacitors
inherently have a higher dissipation factor due to their normally high internal leakage characteristics.In
some cases,if the D (dissipation factor) is excessive,measurement accuracy may degrade and even read out
of specification.
Inductance
Some inductors are intended to operate at a certain DC bias to achieve a certain inductance value.
However,the LCR meters cannot produce such biasing scheme and external biasing should not be attempted
because external power would be applied to the instrument and cause serious damage to the meter.
Therefore, in some cases,measured inductance reading may not agree with manufacturer’s specification.It
is important to check if specification pertains to DC biasing or not.
Resistance
When measuring resistance of devices,it is important to know that there are two types or ways of
measurement.One type is DC resistance measurement. Another type is AC resistance measurement.The
LCR meter provide both of types for
measurement.When measuring a resistive component that is designed to be measured with DC, readings
will be incorrect or inaccurate.Before using the meter to measure resistance,please verify whether the DUT
(device under test) requires DC or AC resistance measurement method. Depending on the method,results
will vary greatly.
7-4 Guard Terminal
One of the input sockets and terminals is labeled as "GUARD".
This terminal does not have to be used in all instances for the meter to make measurements.But in some
instances,it is very useful.Guard terminal generally serves two purposes.
If user is using test leads, the guard terminal can be used to connect to the shielding of the test leads.Doing
so can be useful when making large resistive component measurements.For example, when measuring a
10MΩ resistor with test leads,at the high range the reading may seem to be unstable as a few digits may
continuously be changing.Having the shield of the test leads connected to the guard terminal will help
stabilize the reading in some instances.
Guard terminal is also used to minimize noise and to help minimize parasitic effects coming from the
component to be measured, thus allowing high precision results.
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