5320A-LOAD
High Voltage Load Adapter
2
Turn on the power to the Load’s cooling fans by
pressing the front-panel power switch so the “1”
side of the switch is depressed (see Figure 2). A
light on the power switch illuminates to indicate
that power is connected to the fans. The power
switch to the fans may be turned off when the
Load is no longer being used.
Using the Load for Leakage
Current Testing
The Load resistor should be selected based on
the appropriate voltage amplitude used for the
test or the value recommended in the hipot
tester’s calibration procedure.
W
Caution
To avoid damage, never exceed the
maximum rated voltage, power, and
current limit of the Load.
Usage Limits for Safe Operation
Safe operation of the load depends both on the
amount of voltage and the length of time it is
applied to the Load. For the 10 k
Ω
, 35 k
Ω
,
50 k
Ω
, 100 k
Ω
, and 250 k
Ω
resistors, the higher
voltage levels have limits to the time that they
can be safely applied. The maximum voltages
can be applied for up to 3 minutes. Due to self
heating, exceeding the 3-minute limit for high
voltages may cause both degradation of
performance and a permanent shift in the
resistor values. However, reduced voltage levels
can be safely applied for increasing longer times.
At specific levels, sustained voltages can be
applied indefinitely. This is graphically shown in
Figure 3 for the 10 k
Ω
, 35 k
Ω
, 50 k
Ω
, 100 k
Ω
,
and 250 k
Ω
resistor sets.
Safe Area
0
1000
2000
3000
4000
5000
6000
1
10
100
Time (min)
V
o
lt
ag
e (
V
)
250 k
100 k
35k/50k
10k
ehq101.eps
Figure 3. Safe Area Chart
As an example, the 100 k
Ω
resistor can
withstand 5500 V for 3 minutes while it can
withstand 4000 V for 60 minutes or longer.
Performance and Verification
Test
With normal operation, the resistance values of
the Load should be verified no less frequently
than once per year. Also, the Load should be
verified if there was a possibility of the resistance
values changing due to excessive heating or
power dissipation.
To verify the electrical performance of the Load,
use one of two following test methods to insure
the load resistors are within specification.
The first test method uses voltage and current
levels that insure the resistors dissipate a
reasonable power when being verified. The
alternative second test method uses a multimeter
to measure the load resistance. Both methods
check to see if it is within 10 % of the nominal
value. The multimeter test uses minimal voltage
and current levels, dissipating negligible power
when measuring the resistance values of the
Load.
Either test method can be used, but the voltage
method is generally recommended as it verifies
the resistance value while the resistor is
dissipating actual power – similar to the normal
usage of the Load. The voltage method signal
levels are based on capabilities of the
recommended voltage calibrators. These levels
use voltages up to 1 kV. It is possible and
acceptable to test using other sources to test at
higher voltages, but staying within the limits of
the Load’s safe area of operation.
Table 1 lists the load resistance nominal value
for each test terminal.
The voltage test method requires applying a test
voltage across each resistance, between the
respective input and COM terminals. The
resulting current through the resistor is
measured, and the value of the resistance is
calculated. A calibrator is used as the precision
voltage source. A multimeter is recommended to
measure the current. Figure 4 shows the test
equipment setup. Refer to Table 1 for the
respective sourced voltage level settings and the
nominal currents to be measured.
