17
Z displayed in Display A is always positive (
≥
0). C, L and R may have negative
values. When measuring C & D, the negative value of C means that the
component under test has the characteristics of an inductor. When measuring
L&Q, the negative value of L means that the component under test has the
characteristics of a capacitor. In theory, the resistance of has the positive value.
However, in some cases, value of R may be negative, which is generated due to
excess correction. In order to eliminate the negative value of R, correct
corrections are needed.
Sub parameter D is the reciprocal of Q, that is, D=1/Q.
2.2.2 Measurement frequency
Different components need signals with different measurement frequencies to
measure. For example, electrolytic capacitor usually needs 100 Hz and120 Hz to
measure, and metalized film capacitor needs 1 kHz or 10 KHz. It depends on
real-world needs.
TH2810B provides four measurement frequencies: 100 Hz, 120 Hz, 1 kHz, and
10 kHz.
2.2.3 Test signal level
TH2810B provides three test signal levels available: 1 V, 0.3 V, and 0.1 V.
An inductor’s inductance value may differ widely depending on the current
through the inductor due to the permeability of its core material. Usually, high
test level is used for normal test of components (such as capacitor, resistor and
some kind of inductor), and low test level is used for those components which
work in the circuit of low level (such as semiconductor device, output impedance
of battery, inductor and nonlinear impedance component). For some devices,
the measurement values differ widely depending on the measurement level, for
example inductor components. And the voltage level actually applied across the
device may be different with the set value, refer to §2.3.6 Signal source
resistance.
2.2.4 Display mode
TH2810B provides two modes: direct and % (percentage deviation).
△
2.2.4.1 Direct
In DIR mode, the measurement values displayed in Display A have their
corresponding units. The following units are used by the instrument:
L: µH, mH and H, 1 H=10
3
mH=10
6
µH;
C: pF, nF and µF, 1 µF=10
3
nF=10
6
pF;
R, Z:
Ω
, k
Ω
and M
Ω
, 1 M
Ω
=10
3
K
Ω
=10
6
Ω
In DIR mode, when DUT hasn’t been connected, in the state of L, R, and Z, there
should be a large variable number displaying in Display A, which is even beyond
display range to be no display. And D/Q value in Display B is a variable number.
