Measurement
Pre-operation Inspection
Verify that the device operates normally to ensure that no damage
occurred during storage or shipping. If you find any damage, contact
your authorized Hioki distributor or reseller.
Check Items
Solution
Is there any wiring break
involving the output
connector or sensor base?
If any, proper measurement cannot be
made. Discontinue use and contact your
authorized Hioki distributor or reseller.
Is the cable insulation
torn?
If there is any damage, electric shock
may result. Discontinue use and have
the sensor Is there any cracking or
repaired.
Is there any cracking or
damage on the jaw?
CAUTION
Do not place conductors carrying currents with frequencies
of 10 kHz or higher in close proximity to the jaw, even if the
device does not clamp them. Current flowing through nearby
conductors may cause self-heating of the jaw, damaging the
device.
This device has the protective resistance (output resistance)
in the signal output circuit. To monitor the output signal, it is
recommended to use a measuring instrument, such as digital
multimeter, that has an input resistance of 1 M
Ω
or higher.
Procedures
1
Attach the device to the host instrument that is
powered off.
2
Turn on the host instrument.
3
Perform a demagnetization (DEMAG) and/or zero-
adjustment (0 ADJ) (if needed).
Refer to “Demagnetization (DEMAG) and Zero-adjustment
(0 ADJ).”
4
Release the jaw lock.
5
Open the jaw.
6
Clamp only one conductor to be measured and close
the jaw.
•
•
Check that the tips of jaw are engaged each other.
If the current direction indication is oriented against the
current direction, a polarity of output signal is reversed.
Source side
Load
side
Conductor
Current
direction
indicator
Current
direction
OK
NO
NO
7
Lock the jaw.
8
Start measurement.
9
On completion of the measurement,
en emove the device
from the conductor.
str
10
Turn off the host in ument.
11
Detach the device from the host instrument.
Demagnetization (DEMAG) and Zero-Adjustment
(0 ADJ)
Immediately after the power is turned on or an over-current
exceeding the rated current is input, an offset can be output.
Because the offset behaves as an error during DC current
measurement, perform a demagnetization and/or zero-adjustment,
going through the following procedure.
1
Open the jaw and press
the demagnetization
(DEMAG) button.
Demagnetization (DEMAG) button
2
Open and close the jaw several times and check if
the offset output is stabilized, observing the host
instrument display.
3
Lock the jaw.
4
Perform a zero-adjustment by turning
the zero-adjust knob (0 ADJ), observing
the offset output displayed on the host
instrument display.
Notch
•
No zero-adjustment can be performed while any current is input.
•
•
•
•
•
Because offset output varies with the surrounding environment
and the ambient temperature (terrestrial magnetism and other
devices that generate magnetic fields), perform the zero-
adjustment at the same location at which measurements will be
made.
If the device is connected to an host instrument with a zero
correction function, align the notch of the zero-adjustment knob
with the upper center.
Mechanical shock, for example from dropping the instrument,
may cause the offset to shift.
If no zero-adjustment can be completed, perform
demagnifications (DEMAGs) several times with the jaw
remaining closed.
When measuring a DC or low-frequency (1 kHz or less) current
of small magnitude, you can increase sensitivity on a relative
basis by wrapping the conductor several times around the jaw.
Wrapping the conductor 10 times will cause the device to output
a signal equal to 10 times the measured current.
• In the high-frequency domain,
when the high-potential side
of a circuit (the High side) is
clamped, measured values
may be affected by common-
mode noise.
Source
Load
Current
High
Low
• 1.5-MHz harmonic noise arising from the operating principle can
be emitted.
• Place the clamped conductor to be measured as close to the
jaw center as possible. Separate other conductors from the
device as far away as possible. Measuring large currents with a
frequency of 1 kHz or more or locating unclamped conductors
carrying 500 A or more of such high-frequency currents close to
the jaw can cause increases in errors or waveform distortions.
Specifications
Accuracy
f.s.
Maximum display value or scale length (This is usually the
maximum value of the currently selected range.)
rdg.
Reading value (The value currently being measured and
indicated on the measuring instrument)
The specs of the CT6845-05 are the same as those of the CT6845
except the output connector and options.
Operating
environment
Indoors, Pollution Degree II, altitude up to
2000 m (6562 ft.)
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