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.
However, normally the current consumption is less than 250 mA. A typical 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 Rosemount 2410 Tank
Hub and the field devices on the tank. With fewer devices on the Tankbus, an even longer
cable would be allowed.
Table 3-4 shows the maximum distance between a Rosemount 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.
Table 3-4: Maximum Distance from Power Source to Field Devices on the Tank for
Different Cable Areas
Cable characteristics Maximum distance to tank (m/ft)
Cross-sectional area Typical loop
resistance (Ω/km)
Maximum Current
consumption (250
mA)
Typical installation
(128 mA)
20 AWG (0.5 mm
2
) 66 212 (695) 414 (1358)
18 AWG (0.75 mm
2
) 42 333 (1092) 651 (2136)
17 AWG (1.0 mm
2
) 33 424 (1391) 829 (2720)
16 AWG (1.5 mm
2
) 26 538 (1765) 1052 (3451)
Related information
Cable selection for the Tankbus
Example 1
The example illustrated in Figure 3-2 includes a tank located 300 m away from a
Rosemount 2410 Tank Hub acting as power supply. In the calculations below it is assumed
that the cable length between the field devices on the tank can be ignored.
The tank is equipped with the following field devices: a Rosemount 5900S Radar Level
Gauge, a Rosemount 2240S Multi-input Temperature Transmitter, and a Rosemount 2230
Graphical Field Display. The total current consumption of the three devices is 110 mA (see
Table 3-2).
Installation Reference Manual
December 2019 00809-0100-2410
36 Reference Manual
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