Emerson Rosemount 2410 Reference Manual page 42

Installation
March 2017
Example 2
The second example, illustrated in
acting as power supply to the field devices on both tanks.
The first tank is located 300 m away from the Rosemount 2410 Tank Hub and the second tank a further
350 m away.
Both tanks have two field devices: a Rosemount 5400 Radar Level Transmitter and a Rosemount 644
Temperature Transmitter. The total current consumption of the two devices is 32 mA (see
page
Figure 3-3. Example of installation on two tanks
Rosemount 2410 Tank Hub
The total operating current of the connected field devices on the two tanks is 32+32 mA=64 mA. This is
within the output capability of the Rosemount 2410 Tank Hub.
Calculations
The tank hub is powered by an intrinsically safe power supply: 12.5 V, 250 mA.
Voltage drop to the first tank:
64 mA x 0.30 km x 42 /km=0.80 V.
Voltage at first tank =12.5 V - 0.80 V=11.70 V.
Voltage drop between first and second tank:
32 mA x 0.35 km x 42 /km=0.47 V.
Voltage at second tank =12.5 V - 0.80 V - 0.47 V=11.23 V.
For both tanks the input voltage to the field devices is above the minimum requirement of 9 V.
The field devices may be connected to the Tankbus via segment couplers as illustrated in
spur length must not exceed 60 m according to the FISCO standard. In the example above, it is assumed
that the voltage drop between the segment coupler and the devices can be ignored.
32
28).
Tankbus
300 m
Voltage drop=0.80 V
Figure 3-3, includes two tanks with a Rosemount 2410 Tank Hub
Rosemount 5400
Level Transmitter
Rosemount 644
Temperature Transmitter
Segment
coupler
Voltage drop=0.47 V
Reference Manual
00809-0100-2410, Rev DA
350 m
Segment
coupler
Table 3-2 on
Figure 3-3. The
Installation