5322A-LOAD
Instructions
6
Performance and Verification Test
With normal operation, verify the resistance values of
the Product at least once per year. Also, verify the
load resistor if there is a possibility of the resistance
values changing due to excessive heating or power
dissipation.
To verify the electrical performance of the Product,
use one of these test methods to ensure the load
resistors are within specification:
•
Voltage Test Method - Use voltage and current
levels that ensure that the resistors dissipate a
reasonable power as they are verified.
•
Mutlimeter Test Method - Use 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 resistance.
Either test method can be used, but Fluke Calibration
recommends the voltage method as it verifies the
resistance value while the resistor disipates actual
power – similar to the normal usage of the Product.
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
Product’s safe area of operation.
Table 3 lists the load resistance nominal value for
each load resistor terminal.
To use the voltage test method, apply 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. Use a calibrator as the precision-voltage
source. Use a multimeter to measure the current.
Figure 6 shows the test equipment setup. Refer to
Table 3 for the respective sourced voltage level
settings and the nominal currents to be measured.
Note
Fluke Calibration recommends a Fluke
5520A or 5500A Calibrator as a source
for the voltage method due to its output
voltage/current capabilities. Fluke
Calibration recommends a Fluke
8845A Digital Multimeter (or
equivalent) for measurements with
either test method.
For the voltage test method, test each resistor as
follows:
1. Apply the recommended voltage (V
s
) at power
mains frequency (either 50 Hz or 60 Hz) between
the terminal for the resistor being measured and
the COM terminal.
2. Measure the current (I
m
) flowing through the load.
3. Calculate the resistance (R
L
) by dividing the
sourced voltage by the measured current
(R
L
=V
s
/I
m
).
The calculated resistance should be within 10 % of
the nominal resistance value found in Table 3.
Repeat steps 1 through 3 for each load resistor
terminal and adjust the applied voltage per Table 3.
For the alternative multimeter test method, measure
each resistor as follows:
1. Place the probes of a multimeter between the
selected resistor input (red) terminal and the COM
terminal.
2. Read the measured resistor using the resistance
mode of the multimeter, and note the value.
3. Ensure the measured value is within 10 % of the
nominal resistance.
Repeat steps 1 through 3 for each load resistor
terminal per Table 3.
