Hioki 9754, Инструкция по эксплуатации, Страница: 14 / 30

1.2 Names and Functions of Parts
10
• Acoustic resonance may occur depending on the
level and frequency of the measured current, but
this will not affect measurement unless a foreign
substance such as dust is present on the contact
surfaces of the sensor head.
• If there are high frequency elements included in
the measured current, it will generate high heat.
When taking measurements be cautious of the
sensor heating up.
• The output of this device is terminated inter-
nally. When connecting with a waveform mea-
suring instrument, use an instrument with an
input resistance of 1 M

or higher. Accurate
measurement cannot be made at 50

input
resistance.
• When monitoring high frequency waveform cur-
rent elements superimposed on direct current or
commercial frequency current, it is necessary to
pay attention to the following. Attenuation char-
acteristics in the low frequency area are affected
by direct current or commercial frequency current
levels. As the current level increases, magnetic
saturation of the sensor magnetic core causes a
decrease in amplitude and can generate wave-
form distortion. For example, with a sine wave
input of 15 Apeak, 15 kHz, product specifications
will not be met if the superimposed DC current
exceeds approximately 8 A. Input current levels
must be in accordance with " Derating according
to frequency" (

p.19).
• When clamping together on the round-trip con-
ductors of a commercial circuit, position the two
conductors as close together as possible. The
output value is influenced by the position of the
conductors in the clamp opening. Even if the
round-trip current levels are equal, the clamp
sensor output value may not equal zero. If two
approximately

10 mm conductors are mea-
sured in the round-trip state, and the current
flowing in the conductors is 100 A (55 Hz), the
clamp output value may be approximately 50
mA.