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Wiring Precautions; Meter Size - Toshiba LF434 /LF620 Manual

Electromagnetic flowmeter
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Wiring Precautions

(1) Explosion proof type flowmeters are not provided
with cable glands.
Refer to the part Cable connection port at detector
and converter.
(2) Connect the grounding wire (IV wire 5.5mm² or
more) to a good earth ground (100Ω or less ground
resistance). Make the wire as short as possible. Do
not use a common ground shared with other
equipment where earth current may flow. An
independent earth ground is recommended.
(3) The allowable cable lengths between the detector
and converter for the separate type flowmeter
depend on the electrical conductivity of the object
fluid. See Figure 8.
(4) DO1, DO2, and DI use the same common terminal
(COM). This COM can not connect to other
equipment which have their own ground terminal.
(Power supply for connecting to DI or DO, etc.)
Need to wire separately.
Wiring
Precautions
)
Modbus
(1) For wiring path, avoid places near electrical
equipment that may cause electromagnetic induction
or electrostatic induction interference (such as a
motor, transformer and wireless transmitter).
(2) Use a PROFIBUS-PA cable for signal cable or a
RS485 twisted-pair cable.
In addition, make sure to use a shielded cable to
improve noise resistance. Furthermore, installation
of signal cable in metal conduit is recommended.
(3) General PROFIBUS-PA cables are designed for
indoor use where cables are not exposed to humidity,
rain, etc. When you install cables, make sure to
check the operating conditions such as the operating
temperature range of the cable by contacting its
manufacturer.
(4)When you carry out cable end treatment of
PROFIBUS-PA cable, use a dedicated cable stripper
to avoid the core wire of the cable being nicked or
damaged. In addition, for cables, be careful of
allowable maximum bend diameter. (Do not allow
excessive twisting or bending of cables).
(5)Consider installing a PROFIBUS-PA arrester in the
communication path of PROFBUS-PA so that the
electromagnetic flowmeter will not be affected by
lightning, etc.
(PROFIBUS
or
(6) The electromagnetic flowmeter is not equipped with
terminating resistors. Use the terminating resistor
unit for PROFIBUS-PA or junction box, if
necessary.
(7) Only one PROFIBUS-PA cable goes through a
cable gland of the Electromagnetic Flowmeter.
Please use the junction box at system
configuration
.
(8) Install a terminator to flowmeter that connects
to end of Modbus network.
300
200
100
50
30
20
10
5
3
3
5
10 20 30 50 100 200
Conductivity (μS/cm)
Figure 8. Electrical Conductivity and
Cable Length

Meter Size

To select the meter size:
See Table 3 to 4 and find meter sizes within the velocity
of 0.3 to 32.8 ft/s (0.1 to 10m/s) for a specified full-scale
(measuring range high limit) flow. Select one that has
its full-scale velocity between 3.0 and 10 ft/s (1 and
3m/s).
Note: Make sure the full-scale flow rate used for the final
planning stage stays within 32.8ft/s (10m/s) in terms of
flow velocity.
Table 3. Flow Rate and Flow velocity (English unit)
Size
(inch)
0.328 ft/s
0.98 ft/s
1/2
0.2801
0.8403
1
0.7781
2.334
1.992
1 ½
5.975
2
3.112
9.337
3
7.967
23.90
4
12.45
37.35
6
28.01
84.03
49.80
8
149.4
10
77.81
233.4
12
112.0
336.1
14
152.5
457.5
16
199.2
597.5
252.1
18
756.3
20
311.2
933.7
24
448.2
1344.0
TIC-LF434H
Unit: gal/min
Flow rate
3.0 ft/s
10 ft/s
32.8 ft/s
2.561
8.532
28.01
7.115
23.72
77.81
60.71
18.21
199.2
28.46
94.86
311.2
72.85
242.8
796.7
113.8
379.4
1,245
256.1
853.8
2,801
1,518
455.3
4,980
711.5
2,372
7,781
1,025
3,415
11,200
1,394
4,648
15,250
1,821
6,071
19,920
7,684
2,305
25,210
2,846
9,486
31,120
4,098
1,3660
44,820
9

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