EN.IO.APC.APR.ALW
20
Revision 02.A.005/2020.06
The maximum resistance value in the power circuit (along with the power cables resistance) is de-
fined by the formula:
(for transmitters in Exd, Exi/Exd version)
(for transmitters in standard, Exi version)
where
:
U
– voltage at the supply terminals of the 4…20 mA current loop [V].
Umin
– minimum supply voltage of transmitter
➔
Permissible transmitter supply voltages
R
L_MAX
– maximum power supply line resistance [Ω].
7.2.6. Shielding, equipotential bonding
When using a cable in the screen, connect the screen on one side at the transmitter
’s power supply
point.
7.3. Equipotential bonding
When using an intrinsically safe transmitter with an additional overvoltage protection, having the des-
ignation
“SA version” on the plate, the transmitter should be powered from a galvanically separated
power source or, if this is not possible, equipotential bonding of the transmitter and the power supply
device should be ensured by means of equipotential bonding conductors. In this respect the locally
applicable regulations must be observed.
7.4. Overvoltage protection
Transmitters comply with EMC standards for safety-related products used in general industrial envi-
ronment. Transmitters in standard and flameproof versions are fitted with overvoltage protection. In
intrinsically safe transmitters, in order to increase the resistance to excessive surge, it is possible to
use the overvoltage protection
SA
version. Transmitters with integrated overvoltage protection
SA
should be grounded.
Overvoltage protection parameters in transmitters in standard, Exd or Exi SA versions:
−
discharge threshold voltage: 230 V DC;
−
discharge threshold impulse voltage: 450 V (impulse 100
V/µs);
−
discharge threshold impulse voltage: 600 V (impulse 1000
V/µs);
−
discharge current for 1 surge
: 20 kA, 8/20 µs;
−
discharge current for 10 surges: 10 kA, 8/2
0 µs;
−
discharge current for 300 surges
: 200 A, 10/1000 µs.
7.5. Final inspection of cabling
After completing the electrical installation of the transmitter it is necessary to check the following:
−
does the supply voltage measured at the transmitter terminals at maximum set current match
the range of supply voltage specified on the transmitter nameplate?
−
Is the transmitter connected according to the information given in section (
➔
to transmitter internal terminals
)?
−
Are all the screws tightened?
−
Are the transmitter covers tightened?
−
Are the cable gland and the gland plug tightened?
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