Agilent Technologies 4263B, Operation Manual

Page: 120 / 325

4263B
When measuring DCR or R2 , the actual test current level through the DUT can be obtained as
follows:
The source resistance , Rs , is selected by measured the DUT's resistance value , R
DUT
.
DC Resistance V alue Rs
0 R
DUT
1 25
1 < R
DUT
100
The actual current value , I, is calculated using the following equation:
I =
62
R
D U T
+ R s
T est Current Transient
When measuring the DC resistance of a DUT that has reactive characteristics , you must pay
attention to the transient phenomena of the measurement circuit.
Figure 3-13 shows the transient current of L - DC Resistance measurement.
The measurement circuit for a inductance measurement is shown in simplied form in
Figure 3-13 (a). The equivalent model of the DUT is series R-L.
The test signal, E(t), shown in Figure 3-13 (b), is applied to the measurement circuit and test
current I(t) ows as shown in Figure 3-13 (b).
If the DUT's time constant, which is obtained by
L
R
, is large , it will take a long time for the test
signal to reach a steady state , which is expressed by the dotted line in Figure 3-13 (b).
The 4263B has measurement delay times , T d
1
or T d
2
, at each point when the test signal level
changes . T d
1
is the trigger delay time , which is set by the delay key (refer to \Delay Key
"). T d
2
is decided as follows:
Trigger Delay
Setting (T d
1
)
Delay Time in DC Resistance
Measurement (T d
2
)
0 td
1
40 ms 40 ms
40 ms < td
1
T d
2
= T d
1
Y ou must set the delay time so that the measurement will be started when the test signal has
reached a steady state . F or selection of delay time , depending on the L, refer to \Measuring
High Inductance Transformers" in Chapter 6.
Function Reference and T echnical Information 3-33
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