Appendix 6 Zero Adjustment
A8
To perform zero adjustment appropriately
Table 1 shows the correct and wrong connections. The resistances in the figure indicate
lead resistances; there will be no problem if they are less than few respectively
In (a), if you connect SENSE A and SENSE B as well as SOURCE A and SOURCE B
respectively, and use one path to make connection between SENSE and SOURCE, no
potential difference occurs between SENSE A and SENSE B, and 0 V is input. This enables
zero adjustment to be carried out correctly.
In (b), on the other hand, if you connect SENSE A and SOURCE A as well as SENSE B
and SOURCE B respectively, and use one path to make connection between A and B,
I ×
R
Short
voltage occurs between SENSE A and SENSE B. For this reason, the pseudo 0
connection state cannot be achieved and zero adjustment cannot be carried out correctly.
Table 1: Connection methods
(a) Use one point each between
SENSE and SOURCE for
connection
(b) Use one point each between
A and B for connection
Resistance between
SENSE A and
SENSE B
R
SEA
+ R
SEB
R
SEA
+ R
Short
+ R
SEB
Measurement current
I's flow path
R
SOB
→ R
SOA
R
SOB
→ R
Short
→ R
SOA
Voltage occurring be-
tween SENSE A and
SENSE B
0 I × R
Short
As connection method
for zero adjustment
Correct Wrong
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