Toshiba LF654  Wiring Precautions Profibus or Modbus,  Meter Size, To select the meter size

TIC-LF654L

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 10.

(4)DO1, DO2 and DI use the same common terminal (COM). This COM can not be connected to other equipment which have their own ground terminal. (Power supply for connecting to DI or DO, etc…) Need to wire separately.

Wiring Precautions (PROFIBUS or 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 or a RS485 twisted-pair cable for signal cable.

In addition, make sure to use a shielded cable to improve noise resistance. Installation of signal cable in metal conduit is recommended.

(3)General 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, 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.

(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 connected to end of Modbus network.

	300
	200
(m)	100
	50
length
	30
	20
cable
	10
Allowable	5
	3
	3	5	10 20 30	50 100 200
		Conductivity (μS/cm)

Figure 10. Electrical Conductivity and Cable

Length

Meter Size

To select the meter size:

See Table 2 and 3 to find meter sizes within the velocity of 0.3 to 39.4 ft/s (0.1 to12m/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 39.4ft/s (12m/s) in terms of flow velocity.

Table 2. Flow Rate and Flow velocity (English unit)

			Flow rate		Unit: gal/min
Size
(inch)	0.328 ft/s	0.98 ft/s		3.0ft/s	10 ft/s	39.4 ft/s
1/2'	0.2801	0.8403		2.561	8.532	33.61
1	0.7781	2.334		7.115	23.72	93.37
1 ¼	1.275	3.824		11.66	38.86	153.0
1 ½	1.992	5.975		18.21	60.71	239.0
2	3.112	9.337		28.46	94.86	373.5
2 ½	5.260	15.78		48.09	160.3	631.2
3	7.967	23.90		72.85	242.8	956.1
4	12.45	37.35		113.8	379.4	1,494
5	19.45	58.35		177.9	592.9	2,334
6	28.01	84.03		256.1	853.8	3,361
8	49.80	149.4		455.3	1,518	5,975
10	77.81	233.4		711.5	2,372	9,337
12	112.0	336.1		1,025	3,415	13,445
14	152.5	457.5		1,394	4,648	18,300
16	199.2	597.5		1,821	6,071	23,902
18	252.1	756.3		2,305	7,684	30,251

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