Hioki BT4560 Instruction Manual page 138

Influence of the Eddy Current
Appx. 6 Influence of the Eddy Current
Measurement close to the metal body causes an eddy current to flow due to the dynamic magnetic field that is
generated by the measurement current of the instrument.
This eddy current generates an inductive voltage with a phase opposite to the measurement current in the
measurement probe. The inductive voltage generated cannot be removed even in the synchronous detection
circuit. Therefore, it may cause a measurement error.
Thus, the measurement instrument using the AC signals needs to take into account the influence of the eddy
current.
To suppress the influence of the eddy current, you must not bring the measurement probe without a four-
terminal pair structure close to a metal body.
Appx. 7 Zero Adjustment
Zero adjustment is a function that compensates for the value remaining when a resistance 0
and then adjusts the zero-point. Thus, zero adjustment must be carried out under conditions where a
Ω
resistance of 0 is connected. However, It is very difficult and impractical to connect a sample that has a zero
resistance value.
Accordingly, zero adjustment is actually carried out to adjust the zero-point by creating conditions where a
pseudo resistance of 0
To create the conditions where a pseudo resistance of 0
When the ideal resistance of 0
voltage between SENSE-H and SENSE-L becomes 0 V. That is, if the voltage between the SENSE-H and the
SENSE-L is made to be 0 V, the same conditions as when a resistance of 0
When performing zero adjustment with this instrument:
This instrument monitors the condition of the spaces of the four measurement terminals by the measurement
fault detection function. Accordingly, zero adjustment needs to be properly connected to each space of the
terminals. (Figure. Conditions Where a Pseudo Resistance of 0
First, create a short-circuit between SENSE-H and SENSE-L to cause the voltage between SENSE-H and
SENSE-L to be 0 V. If the wiring resistance of the cable being used R
resistance of the wiring can be ignored. The explanation is as follows. The SENSE terminals are the voltage
measurement terminals, and thus the current I
When the resistance of wiring R
almost zero.
Next, connect the spacing between SOURCE-H and SOURCE-L.
This prevents an error display when the measurement current cannot be flown. The wiring resistance of the
cable used R + R
SOH SOL
In addition, when monitoring the connection condition between SENSE and SOURCE, the spaces between
SENSE and SOURCE must be connected. If the wiring resistance of the cable used R
Ω
several , the cable is acceptable.
The above wiring makes the measurement current I that flows out from SOURCE-H flow into SOURCE-L,
and thus prevents the measurement current that flows out from SOURCE-H from flowing into the wiring of
SENSE-H and SENSE-L. Consequently, the voltage between SENSE-H and SENSE-L can be maintained
accurately at 0 V and zero adjustment can be performed.
8
A
Ω
is connected.
Ω
is connected, from the relational expression of Ohm's law E = I × R , the
is ignored. In the relational expression, E = I
0
+ R is several
SEH SEL
must be less than the resistance value with which the measurement current can flow.
Ω
is connected:
Ω
Ω
is Connected)
+ R
SEH SEL
Ω
, the voltage between SENSE-H and SENSE-L becomes
Ω
is measured
is connected can be created.
Ω
is less than several , the
×( R + R ), I
0 SEH SEL
is approximately
Short
≈0.
0