VA Master FAM540
METAL CONE VARIABLE AREA FLOWMETER | OI/FAM540-EN REV. E
13
Figure 3: Terminals 31 / 32, power supply / load
U
V
Power supply
R
B
Maximum permissible load in the power supply (z. B. indicator)
The minimum voltage U
V
= 0 V is based on a load of 0
Ω
.
Signal cable
The Ex calculations are based on temperatures of 80 °C (176 °F)
at the cable input. For this reason, cables with a specification of
80 °C (176 °F) must be used.
For cables limited to 70 °C (158 °F), a maximum ambient
temperature of T
amb
= 60 °C (140 °F) applies.
The resulting new maximum measuring medium temperatures
are determined as follows:
• Calculate a new ambient temperature:
T
amb
new = T
amb
+ 10 °C (18 °F).
• Use the calculated ambient temperature T
amb
new to
determine the new associated permissible measuring
medium temperatures in the tables.
• Please use the limit value tables with the original ambient
temperature T
amb
to determine the relevant temperature
class. See
Safety specifications ATEX / IECEx
on page 14,
Tables 1 to 5.
Example:
• T
amb
= 50 °C (122 °F) becomes T
amb
new = 60 °C (140 °F).
• Determine the measuring medium temperature T
amb
= 60
°C (140 °F).
• Determine the temperature class for T
amb
= 50 °C (122 °F).
Earthing
1
Ground terminal
2
Potential equalization in accordance with EN 60079-0
Figure 4: Grounding
The FAM540 housing must be correctly earthed in order to
ensure proper function and safe operation.
Copper wires with a minimum cross-section of 6 mm
2
(AWG 10)
must be used to connect to the potential equalization.
Note
The operator must make sure that when connecting the
protective ground (PE), there are no potential differences
between protective ground (PE) and potential equalization, even
in the event of a fault.
Change from two to one column
