A40B
Instruction Manual
16
Operating Instructions
Introduction
This section of the manual describes how to measure both AC and DC current using any
one of the Current Shunts. The procedures are based on the assumption that the user is
familiar with the
Operating Information
and
Specifications
presented earlier in this
manual.
Measuring Current
Use the following procedure to measure current using one of the Current Shunts:
1.
Analyze the circuit being tested and determine the following:
a.
The approximate value of the current that flows in the circuit.
b.
The frequency of the current to be measured (DC to 100 kHz).
2.
Select a Current Shunt capable of safely handling the estimated current.
3.
If using the 1 mA Current Shunt, switch it to On and verify that the battery low (red)
indicator is off. If the 1 mA Current Shunt has been charging, disconnect the charger.
The charging process creates heat in the battery so for the best accuracy allow the
shunt temperature to stabilize for 100 minutes after charging completes.
4.
Remove power from the circuit under test and connect the input of the Current Shunt
in series with the circuit.
5.
Connect an appropriate voltage measuring device to the output of the Current Shunt,
and select the correct range. The output voltage of the Current Shunt is proportional
to the input current; 0.8 V for nominal rated current.
It is generally appropriate to set the measuring device to remote guard and connect its
guard terminal to the guard on the Current Shunt. Refer to the measuring device
documentation.
6.
Apply power to the circuit and measure the resulting output voltage. This output
voltage is directly proportional to the current flowing in the circuit.
7.
Use the voltage measurement and the
Operating Information
in the previous section
of this manual to accurately determine the current level.
Determine the current using the following formula:
Where: AC-DC calibrated and Loading error are expressed in ppm.
⎟
⎠
⎞
⎜
⎝
⎛
−
×
⎟
⎠
⎞
⎜
⎝
⎛
+
×
⎟⎟
⎠
⎞
⎜⎜
⎝
⎛
=
1,000,000
error
Loading
1
1,000,000
DC
-
AC
1
R
calibrated
calibrated
V
I
Summary of Contents for A40B
Page 6: ...A40B Instruction Manual iv...
Page 8: ...A40B Instruction Manual vi...
