Hioki RM3542, Instruction Manual, Page: 206 / 218

Appendix 9 Zero Adjustment
A
16
Zero adjustment is a function which adjusts the zero point by deducting the residual
value obtained during 0

measurement. For this reason, zero adjustment must be
performed when connection is made to 0

. However, connecting a sample with no
resistance is difficult and therefore is not practical.
In this respect, when performing the actual zero adjustment, create a pseudo
connection to 0

and then adjust the zero point.
To create 0

connection state
If an ideal 0

connection is made, the voltage between H
POT
and L
POT
becomes 0 V
according to the Ohm's Law of E = I
×
R . In other words, if you set the voltage
between H
POT
and L
POT
to 0 V, this gives you the same state of 0

connection.
To perform zero adjustment using the instrument
The instrument uses a measurement fault detection function to monitor the state of
connection between the four measurement terminals. For this reason, when
performing zero adjustment, you need to make connections between the terminals
appropriately in advance (Figure 1).
First, short between H
POT
and L
POT
to set
the voltage between H
POT
and L
POT
to 0 V.
If lead resistances R
SEH
and R
SEL
of the
cable are less than few

, there will be no
problem. Because the POT terminal is a
voltage measurement terminal, almost no
current
I
0
flows. Therefore, in the E = I
0
×
(
R
SEH
+
R
SEL
) formula,
I
0

0 is achieved; if
lead resistances R
SEH
and R
SEL
are less
than few

, voltage between H
POT
and L
POT
will become almost zero.
Next, make connection between H
CUR
and
L
CUR
. This is to avoid display of error when
no measurement current flows through.
Lead resistances
R
SOH
and R
SOL
of the
cable must be less than the resistance for
flowing measurement current.
Furthermore, if you also monitor the connection between POT and CUR, you need to
make connection between POT and CUR. If lead resistance
R
Short
of the cable has
only few

, there will be no problem.
If you wire in the way described above, measurement current I flowing out from H
CUR
will go to L
CUR
but not to the lead of H
POT
or L
POT
. This enables the voltage between
H
POT
and L
POT
to be kept accurately at 0 V, and appropriate zero adjustment
becomes possible.
Appendix 9 Zero Adjustment
E = ( I
0
× R
SEL
) + ( I
0
× R
SEH
)
= (0 ×
R
SEL
) + (0 ×
R
SEH
)
= 0 [V]
Figure 1. Pseudo connection to 0
