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Section 3
OM6624CT-3000-5-00
11 May, 2016
3-2
Step 3)
Make sure the selection of working standard resistor is appropriate and the
current range selected for the test is within the range of test currents to be
measured. Usually a 1 reference is chosen for the 3 A Burden and a 10
reference is chosen for the 150 mA Burden. See Table 3-1.
Step 4)
Turn on the power for each component of the system in the following order:
-
The 6623A-3S Control Unit.
-
The DVM.
-
The 66259 Extender Control Unit if utilized.
-
The CS1000 Current Sources up to three units only; or the separate
current source.
Note:
Always turn the Current Source on LAST after the 6623A-3S Control Unit
and the 66259 Extender Control Unit are turned on. And, always turn the Current
Source off FIRST before turning off the 6623A-3S or the 66259. Never turn the
Current Source off or on while a measurement is in progress.
Step 5)
Select initially a test current of one tenth the desired current.
Step 6)
Check that the null meter indicator on the 6623A-3S moves to the right or
left side initially then returns to the centre line within the graduation lines
of the meter. A small offset is a satisfactory indication that a balance
condition exits on the 6624CT-3000 Transformer Unit.
Step 7)
Increase the test current to the desired magnitude and observe that the meter
indicator moves to the right or left side initially then returns to the centre
line within the graduation lines of the meter.
Step 8)
Change the polarity of the current source if possible and use the DVM to
measure the average potentials on the reference shunt so as to determine the
magnitude of the test current positive and negative values. The primary test
current can then be determined by the following formula:
Primary Test Current = Range Ratio x (Vref / Rref)
Where:
Range Ratio
is the Range selected on the 6624CT-3000 Transformer Unit.
Vref
is the average magnitude of the absolute positive and
negative potentials on the reference shunt.
Rref
is the calibrated resistance value of the reference shunt.
Note that where the reference shunt is used on the 150 mA Burden terminals, the
Range Ratio is twenty times the selection on the 6624CT-3000 Transformer Unit.
Содержание 6624CT-3000
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