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Connect the loading unit to the control unit as shown in figure 2.1. When switched on, the
control unit will automatically detect the loading unit type.
Set the metering range switch to 10%, 50% or 100%. These ranges refer to % of maximum
rated current of the connected loading unit, so for an NLU5000 100% is 5000A and for an
NLU2000 100% is 2000A.
Select the desired output on the loading unit. One output lead always connects to the
common terminal, and the other connects to one of the three output taps. Use the correct tap
for the voltage and current that you require. The output leads should always be attached
using fully tightened stainless steel nuts, bolts and washers. Connect the output cables to the
test object.
HOT
After testing, the output terminals and leads may be hot. Allow to
cool before touching connections.
Connect the supply lead to the mains and switch the supply circuit breaker on. The supply on
lamp should now illuminate.
2.1.2
Testing
Always start the first test with the output control knob at zero to ensure that the test object is
not subjected to an unintentional over-current.
Switch the output on using the “on” pushbutton and then increase the output current to the
desired test current. If you cannot achieve the desired test current, one of the following will be
limiting the current:-
Output leads too long. Use shorter output leads.
Output leads in a large loop – minimising the area in the loop of the output leads will
maximise the current available.
Output leads of insufficient cross-sectional area. Either use thicker output leads or use
two output leads per connection.
2.1.3
After Testing
On completion of the test, switch off the output using the “off” pushbutton. Return the output
control to zero and switch off the supply. Before disconnecting the test object ensure the
mains supply switch is in the OFF position.
