Atlas
LCR45
User Guide
January 2019 – Rev 4
Page 10
Admittance Display
Admittance is the inverse of the Complex Impedance. It can be considered in
the same way that
conductance
is the inverse of
resistance
.
Impedance consists of
resistance
and
reactance
.
Admittance consists of
conductance
and
susceptance
.
Admittance has the units of Siemens (also known as Mhos).
The imaginary part of the admittance is known as
susceptance
.
Note that it is not possible to display admittance if the test frequency
is set to DC (either automatically or manually). You will see
on the
admittance screen when testing at DC.
How the LCR45 uses Susceptance
The LCR45 uses the value of susceptance to calculate capacitance.
Susceptance of a capacitor is 2
π
f
C.
Calculating the capacitance from its susceptance figure enables the LCR45 to
reduce the influence of dielectric dissipation and parallel leakage on readings.
Over-range Values
Sometimes you may see over-range or erratic values for the impedance or
admittance measurements.
An open circuit can render an extremely high value of Impedance (real and/or
imaginary parts) and is difficult to mathematically resolve. Similarly, a very
low impedance part (such as a short circuit) will result in a very high
Admittance measurement that is also difficult to mathematically resolve. This
is not an indication of a measurement problem.
