Nivus OCM F, Инструкция по эксплуатации

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Installation and Connection
OCM F - rev. 05 / 06.04.2018 page 29
14.7 Overvoltage Protection Precautions
Reduction of the possible cable length with overvoltage protection
The use of overvoltage protection elements for sensors in Non-Ex areas will reduce the
maximum possible cable length.
The line resistance is 0.3 Ohm/wire. This resistance must be taken into account consider-
ing the allowed total resistance.
Observe the “Technical Instructions of Doppler sensors”.
Overvoltage protection elements are subject to natural wear and tear and therefore shall be
inspected regularly and replaced if necessary in the course of maintenance measures as
well as after electric malfunctions.
For effective protection of the OCM F transmitter it is necessary to protect power supply and
mA inputs and outputs.
NIVUS recommends
•
for the mains supply the types
>EnerPro 220 Tr< for 230 V AC
and/or
>EnerPro 24 V< for 24 V DC
•
for the mA-out-/inputs the type
>DataPro 2x1 24 V / 24 V<
The flow velocity sensors are internally protected against overvoltage. In case of an expected
high hazard potential it is possible to protect the sensors by using a combination (on a single
end) of the following Types.
•
for Ex sensors
>SonicPro 3x1 24 V / 24 V Ex<
and
>DataPro 2x1 12 V / 12 V 11μH Tr (N)<
•
for Non-Ex sensors
>SonicPro 3x1 24 V / 24 V<
and
>DataPro 2x1 24 V / 24 V Tr<
Permissible cable length
If using the sensors in Ex areas consider the connected loads of the overvoltage protection
devices as well as capacity and inductance of the NIVUS sensor cables (KDA) additionally.
The maximum permissible NIVUS cable lengths in Ex areas are:

Single-side overvoltage protection: 135 m

Double-side overvoltage protection: 120 m
Observe the connection direction
Observe the non-reversed connection (p-side to transmitter) as well as a correct, straight
wiring supply. Ground (earth) must lead to the unprotected side.
The overvoltage protection devices are ineffective if wired incorrectly.