YOKOGAWA DR130, Руководство пользователя

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3-31
IM DR231-01E
Installation and Wiring
3
3.8 Countering Noise
• for input lines: an increase of impedance;
Always separate the input line from the noise source lines (power and alarm lines).
Step 1 : Install a separator.
Separator
Special class 3 ground
(10
Ω
or less)
Signal*
lines
Power
lines
Step 2 : Keep the signal cables at least 15cm above the power lines using a bracket.
If the power lines are not shielded, the operating voltage is 220V or less, and the operating
current is 10A or more, the distance between the signal cables and power cords must be
60cm or more.
Signal lines*
Power
lines
at least
15 cm
Step 3 : Leave a clearance of at least 15 cm between the signal lines and power lines.
If the power lines are not shielded, the operating voltage is 220V or less, and the operating
current is 10A or more, the distance between the signal cables and power cords must be
60cm or more.
Signal*
lines
Power
lines
at least 15 cm
Step 4 : Lay the signal lines at right angles to the power lines.
If the power lines are not shielded, separate the signal lines and power lines where they cross
using steel sheeting at least 1.6mm thick.
Signal lines*
Power lines
1.6mm
* Separate analog signal lines and communication cables in the same manner as from power
cords.
• When there is influence from a magnetic or electrical field: an increase of
impedance
Step 1 : Keep the noise source as far away as possible.
Magnetic field strength H=
I
2
π
r
=
2,400
6
=400 A/m
Example
I=2,400A
r=1m
H
The influence of the external magnetic field on the measuring instrument: 400A/m or less.