12
100.16
=
100.04
=
= 10.01 mV
= 10.00 mV
The error will be about 0.01mV
the error is not significant
CURRENT MEASUREMENTS
All of the controls and terminals used to make current measurements are located on the front panel. The
AC mA and DC mA function switches determine the measurement function. The colored area around the
20A switch extends up and to the right to enclose the six range values for the 20A measurement function.
Push the range switch immediately above the value to be measured.
As the colored areas around the terminals indicate, the red test lead should be plugged into the 2A or 20A
terminal and the black test lead should be plugged into the COMMON terminal.
WARNING
INSTRUMENT DAMAGE AND OPERATOR INJURY MAY RESULT IF THE FUSE BLOWS WHILE
CURRENT IS BEING MEASURED IN A CIRCUIT WHICH EXHIBITS AN OPEN CIRCUIT VOLTAGE
GREATER THAN 600 VOLTS.
Burden voltage error
When a meter is placed in series with a circuit to measure current, you may have to consider an error
caused by the voltage drop across the meter (in this case, across the protective fuses and current
shunts). This voltage drop is called burden voltage. The maximum full scale burden voltages for your
instrument are: 0.3V for the four lowest ranges, and 0.9V for the 2000mA, 20A ranges. These voltage
drops can affect the accuracy of a current measurement if the current source is unregulated and the
resistance of the shunt and fuse represents a significant part ( 1/ 1000 or more) of the source resistance.
If burden voltage does present a problem, the percentage error can be calculated using the formula
below. This error can be minimized by selecting the highest current range that provides the necessary
resolution.
Calculating Burden Voltage Error
E
s
= Source voltage
R
L
= Load resi Source resistance
I
M
= Measured current (display reading in amps)
E
B
= Burden voltage (calculated) , i.e.,
Display reading expressed as a % of full scale
)
Scale
Full
Reading
x
(100
times full scale burden voltage for selected range. See table.
RANGE F.S.
BURDEN VOLTAGE
200µA to 200mA
2000mA
20A
0.3V max.
1V max.
2V max.
E
S
R
L
I
M
E
B
AMMETER SHUNT
