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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 880 LCR meter 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 880 uses AC resistance measurement method and does not provide an
option for DC resistance measurements. Therefore, 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.
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 10 MΩ 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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