30
PN: 81127
Rev 4, 6/2017
Figure 23 - Test Lead Adapter with Screw-in Accessories
Due to the voltage drop from the inductive reactance of the test circuit, a significant loss of current will result
for each inch of test lead. Therefore, when choosing test leads (other than the leads provided) the length
and size of leads chosen will determine the maximum available test current. It is worthwhile to sacrifice
cross section of test leads for the sake of reducing length. Every inch of lead that can be eliminated provides
worthwhile increase in available test current. Heating is not a significant problem in testing, even though
the leads may become hot. Paralleling of sufficient cables provides higher test currents. Each cable can
be fitted with a compression lug on each end, and then bolted to the output terminals of the test set and the
device under test.
The two cables between the test set and the device under test can be twisted together or bundled with tape
or cord to maintain close proximity, which helps to minimize inductive reactance.
3.3
SPI225 Output Current and Overload Capability
The current rating of the output terminals may be exceeded for short durations provided the voltage rating
is sufficient to "push" the desired current through the device under test and the connecting test leads. The
overload capacity, represented by multiples of rated current, versus TIME ON and TIME OFF are given
below.
%Rated
Maximum
Minimum
Current
Time ON
1
Time OFF
100 (1x)
30 minutes
30 minutes
200 (2x)
3 minutes
8 minutes
300 (3x)
30 seconds
4 minutes
400 (4x)
7 seconds
2 minutes
1
Time On will vary depending on the ambient temperature. The SPI is protected against thermal
overload.
