IM 12D7B2-E-H
3-2-4. Access to terminal and cable
entry
1. To access terminals remove the front
cover of the EXA SC200 by releasing the
4 captive screws.
2. Pull the sensor cable into connection
space and connected the wires to the
terminals as indicated by the numbers on
the wires. Make sure all connections are
firm and do not touch each other.
3. Screw the gland securely and tighten it to
keep out moisture. DO NOT use a
wrench to tighten the nut.
4. A hose connection can be used to guide
the cables coming from an immersion fit-
ting through a protective plastic tubing to
the transmitter. This adaptor has to be
bought separately.
3-2. Wiring of sensors
3-2-1. General precautions
Generally, transmission of signals from the
conductivity sensor is at a low voltage and
high impedance level. Thus care must be
taken to avoid interference.
Before connecting the sensor cable to the
transmitter make sure the next conditions
are met:
- the sensor cable is not to be mounted in
tracks together with high voltage and or
power switching cables;
- use only the standard conductivity cable
with a maximum length of 10 metre;
- mount the transmitter within the distance
of the cable.
NOTE:
The outside earth terminal should be con-
nected to site ground by a large area con-
ductor (e.g. a flat earth strip) for best protec-
tion against interference.
3-2-2. Additional precautions for instal-
lations in hazardous areas
Make sure that the total of capacitancesand
inductances connected to the input termi-
nals of the EXA SC200 do not exceed the
limits given in the certificate.This sets a limit
to the cable and extensions used.
The intrinsic safe version of the EXA SC200
instrument can be erected in Zone 1.
The sensors can be installed in Zone 0 or
Zone 1 if a safety barrier according to the
limits given in the system certificate is used.
3-2-3. Grounding the liquid
In all circumstances, the sensor side of the
measuring loop is grounded to the measu-
ring liquid through one of the electrode con-
tacts in the conductivity cell. The supply and
output signal are isolated to avoid uninten-
tional ground loops.
6
Summary of Contents for SC200
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