IM-P192-02
MI Issue 2
26
Fig. 22
V (
vo
lts
)
R (ohms)
TVA flowmeter
operating range
V = 0.022R + 6
9 V
V
28 V
Power supply requirements
A nominal 24 Vdc is needed to power the flowmeter. However, the TVA flowmeter will operate
correctly as long as the power supply is in the range shown in Figure 20. A single, stand-
alone, supply may be capable of powering several transmitters. It can be mounted in a control
room or in the field, but cannot be on the same loop. Follow the power supply manuacturer’s
recommendations with regard to mounting and environmental considerations.
The graph (Figure 22) shows the range of power supply voltages and loop resistances over
which the TVA flowmeter is capable of operating. The loop resistance includes all the wiring.
Cable length
Generally the maximum cable length between the TVA flowmeter and the power supply is
300 m (984 ft).
However the actual cable length is governed by the number of network devices, the total
resistance of the network and the cable capacitance.
Suggested cable type:
for both loop and pulse should be shielded twisted pairs, each core,
seven stranded wire with cross sectional area of 0.5 mm
²
.
EMC cable glands suitable for M20 x 1.5 to EN 50262 / IP68 are recommended.
The cable gland / body torque setting is 13 N m (9.58 lbf ft).
The gland nut torque setting (with cable fitted) is 12 N m (8.85 lbf ft).
