Emerson Process Management Rosemount 2410 Reference Manual, Typical loop, Maximum Current, 128 mA

Reference Manual

300530EN, Rev BA September 2012

Rosemount 2410

Table 3-3. Typical characteristics of instrumentation cable

Table 3-4. Maximum distance from power source to field devices on the tank for different cable areas

Since the field devices on the Tankbus must have at least a 9 V input voltage at their terminals, you will have to take into account the voltage drop in the fieldbus cables. Distances are normally quite short between the Rosemount 2410 Tank Hub and field devices on the tank. In many cases you can use existing cables as long as the FISCO requirements are fulfilled (see “Cable Selection for the Tankbus” on page 3-6). Typical characteristics for such a cable is:

Parameter	Value
	42 Ω/km
Loop resistance
Inductance	0.65 mH/km
Capacitance	115 nF/km
	0.75 mm2 (18 AWG)
Cross-sectional area

The Rosemount 2410 outputs 12.5 Vdc. Considering the minimum voltage supply of 9 V on the field device terminals, a maximum voltage drop of 3.5 V on the Tankbus can be allowed. At a maximum current consumption of

250 mA (12.5 Vdc) with all field devices located at the far end of the Tankbus, a total “worst case” cable resistance of approximately 14 Ω (3.5 V/250 mA) is allowed. This corresponds to a cable length of 333 m (1092 ft) in case typical cable characteristics are assumed as specified in Table 3-3 on page 3-9.

However, normally the current consumption is less than 250 mA. A typical Raptor configuration would include a tank supplied with a Rosemount 5900S Radar Level Gauge, a Rosemount 2230 Graphical Field Display, a Rosemount 2240S Multi-input Temperature Transmitter, and a Rosemount 3051S Pressure Transmitter. In this case the current consumption would be 128 mA allowing a cable length of 677 m (2221 ft) between the 2410 Tank Hub and the field devices on the tank. With fewer devices on the Tankbus, an even longer cable would be allowed.

Table 3-4shows the maximum distance between a 2410 Tank Hub and the field devices on a tank for different cable cross-sectional areas. The table shows the maximum distance to a tank at a total current consumption of 250 mA as well as for a typical installation as outlined above.

	Cable characteristics		Maximum distance to tank (m/ft)
Cross-sectional area		Typical loop	Maximum Current		Typical installation
		resistance	consumption		(128 mA)
		(Ω/km)	(250 mA)
20	AWG (0.5 mm2)	66	212	(695)	414 (1358)
18	AWG (0.75 mm2)	42	333	(1092)	651 (2136)
17	AWG (1.0 mm2)	33	424	(1391)	829 (2720)
16	AWG (1.5 mm2)	26	538	(1765)	1052 (3451)

Section 3. Installation 3-9