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Influence of Noise
11.4
Influence of Noise
Noise transmission path
Electric disturbances in electric circuits and instruments are called noise.
Major noise sources at factories include motors, welding machines, and inverters.
Some electrical noise is transmitted directly from a noise source through communications, power,
and grounding lines and other noise is transmitted by induction (static induction or electromagnetic
induction).
See “Fig. Conductive noise transmission”.
The frequency band is wide and contains a surge, which is strong pulse noise. In addition, there
is also electrical noise caused by the power supply frequency. The noise may affect the measured
values.
Be aware that the measured values may be affected by electrical noise in the following cases.
• The measurement cable is placed near a noise source.
• The measurement cable is placed in parallel with the power supply line of a noise source.
• A power supply is shared with a noise source.
Instrument
RS-232C
LAN
USB
EXT. I/O
Controller
(PC, PLC)
Motor
Welding
machine
Inverter
Power supply line
L
N
PE
Fig. Conductive noise transmission
Precautions for measurement cable wiring
Pay attention to the following to mitigate the influence of noise on the measured values.
Keep the measurement cable away from the noise source and power supply line.
Signal lines are connected with conductive materials, such as metal, with stray capacitance.
Static induction noise is transmitted through this connection.
Since stray capacitance is inversely proportional to distance, a clearance from the noise source is
required.
Ensure sufficient distance in the same manner between signal lines of different types, power supply
and signal lines, input and output lines, and grounding and signal lines as well.
Appendix
HIOKI BT5525A961-00
Содержание BT5525
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Страница 76: ...76 Initializing the Instrument Reset HIOKI BT5525A961 00 ...
Страница 82: ...82 Deleting Panel Data HIOKI BT5525A961 00 ...
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