Toshiba Sanitary Electromagnetic Flowmeter TIC-LF494B - Manual (Page 10)

TIC-LF494B
10
Wiring Precautions
(1) Explosion proof type flowmeters are not
provided 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 (100 Ω 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 11.
(4) DO1, DO2 (opt.), and DI (opt.) use the same
common terminal (COM). This COM can not
connect to other equipments which have their
own ground terminal. (Power supply for
connecting to DI or DO, etc…) Need to wire
separately.
Wiring Precautions (PROFIBUS)
(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. 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 etc. so that the core wire of the cable will
not be nicked or damaged. In addition, for cables,
be careful of allowable maximum bend diameter
etc. (Basically, do not install cables in a way
cables are twisted or bent.).
(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.
(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 .
300
200
100
3
5
10
30
50
3 5 10 20 30 50 100 200
Conductivity ( µS/cm)
A
llow
able
c
able
le
ngth (
m
)
Figure 11. Electrical Conductivity and
Cable Length
Meter Size
To select the meter size:
See Table 2 to 3 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 32.8 ft/s (10m/s) in
terms of flow velocity.
Table 2. Flow Rate and Flow Velocity (English unit)
Unit: gal/min
Flow rate Size
(inch) 0.3ft/s 0.98ft/s 3ft/s 10ft/s 32.8ft/s
1 0.7781 2.334 7.115 23.72 77.81
1 ½ 1.992 5.975 18.21 60.71 199.2
2 3.112 9.337 28.46 94.86 311.2
3 7.967 23.90 72.85 242.8 796.7
4 12.45 37.35 113.8 379.4 1,245
Table 3. Flow Rate and Flow Velocity (SI unit)
Unit: m 3 /h
Flow rate Size
(mm) 0.１ m/s 0.3 m/s 1.0 m/s 3 m/s 10 m/s
25 0.1767 0.5301 1.767 5.301 17.67
40 0.4523 1.357 4.523 13.57 45.23
50 0.7067 2.120 7.067 21.20 70.67
80 1.809 5.428 18.09 54.28 180.9
100 2.827 8.482 28.27 84.82 282.7