OPERATION
2-2
SERIES and PARALLEL EQUIVALENT CIRCUITS
Any non-ideal component can be represented as a resistive component either in series or in parallel with a
reactive component. Depending upon the characteristics of the component and the measurement frequency,
either the series or parallel model will be the more accurate model. The more ideal a component is, the less
the two models differ. However, as Q for inductors decreases towards 10 and Q for resistors or D for
capacitors increases towards 0.1, the series and parallel values begin to diverge. In general, most parts are
best approximated by the series model. Manufacturers often specify which representation should be used
when testing their devices. MIL or industry standards also specify test conditions.
The [Equiv Circuit] key toggles between the two equivalent circuit models. The SERIES or PARALLEL LEDs
indicate which model is active. For the series model, the left display shows the series resistance, inductance,
or capacitance (for R+Q, L+Q, C+D and C+R). The right display will show the quality factor Q, the dissipation
factor D, or the series resistance. For the parallel model, the left display shows the parallel equivalents of the
major parameters (R, L, or C) and the right display shows Q, D, or the parallel resistance. Q and D are the
same for both the parallel and series models.
DISPLAY TYPES
The [Display] key cycles through the five different display types. To cycle between the different displays, press
the [Display] key repeatedly until the appropriate indicator LED is on. Some of the display types are not
enabled unless the instrument is set appropriately. For example, only the Value and Entry displays are
enabled when the instrument is in the AUTO mode.
VALUE
The value display shows the value of the component being measured. The type
of component is indicated by the LEDs above the display (R+Q, L+Q, C+D, C+R).
The units of each display are indicated by the unit LEDs to the right of the each
display. The AUTO LED indicates that the auto select parameter (AUTO) mode is
active. The Value display is enabled under all conditions.
DEV
The DEV, or deviation display, shows the difference between the component
being measured and a previously entered relative value (display =
measured value - relative value). This is useful for measuring small variations in
component values. The DEV display is disabled if the unit is in AUTO mode or if
no nominal value has been entered. To use the DEV display, first enter a nominal
value (see below), then press the display key until the DEV LED is on. Negative
readings mean that the measured value is smaller than the nominal value.
Positive readings mean the measured value is larger than the nominal value.
Entering a Nominal Value
To enter a nominal value, press the [Display] key until the ENTRY display is
selected. Next, press the appropriate parameter key, [R+Q] for nominal
resistance values, [L+Q] for nominal inductance values, and either [C+D] or [C+R]
for nominal capacitance values. The appropriate parameter LEDs will turn on and
the present nominal value (or the default value) will appear in the left display. The
right display will be blank. Enter the new nominal value using the numeric keys
and one of the three enter keys [
Ω
,
µ
H,pF], [k
Ω
,mH,nF], or [M
Ω
,H,
µ
F].
%DEV
The %DEV, or percent deviation display, shows the % difference between the
component being measured and a previously entered nominal value (display =
100 x {measured value - nominal value} / nominal value). Percentages are
displayed to 0.1%. As with the DEV display this display is disabled if the unit is in
AUTO mode or if no nominal value has been previously entered. To enter a
nominal value, follow the proce dure described above.
