Yokogawa EXA ISC202 2-wire Conductivity Transmitter/Analyzer - Manual (Page 35)

IM 12D06A03-01E
Installation and wiring 3-3
DISTRIBUTOR
RECORDER
CURRENT OUTPUT
12 180 100 0
Supply
mA-Output
2,5 or 10 m
SENSORS
Safety Barrier
ISC202S only
INPUT OUTPUT
SUPPLY
COMPUTER
HAND HELD
COMMUNICATOR
MODE
HOLD FAIL
YES N O ENT
MEASURE
DISPLA Y
H O L D
MODE
C A L
Figure 3-6. System configuration
3-3. Wiring of sensors
3-3-1. General precautions
Generally, transmission of signals from Inductive Conductivity sensors is at a low voltage and current
level. Thus a lot of care must be taken to avoid interference. Before connecting sensor cables to the
transmitter make sure that the following conditions are met:
• the sensor cables are not mounted in tracks together with high voltage and or power switching cables.
• only standard sensor cables or extension cable are used.
• the transmitter is mounted within the distance of the sensor cables (max. 10 m) + up to 50 m WF10
extension cable.
• the setup is kept flexible for easy insertion and retraction of the sensors in the fitting.
3-3-2. Additional precautions for installations in hazardous areas
Make sure that the total of capacitance and inductances connected to the input terminals of the EXA
ISC202S 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 ISC202S instrument can be mounted in Zone 0 or 1 (ISC202S-B, -N,
-D).
• The sensor can be installed in Zone 0 or Zone 1 if a safety barrier according to the limits given in the
system certificate is used.
• Ensure that the total of capacitance and inductances connected to the terminals of the EXA ISC202S
do not exceed the limits given in the certificate of the safety barrier or distributor.
• The cable used should preferably have a BLUE colour or marking on the outside.
• Installation for (sensors in Zone 0 or 1):
• Generally, the distributor with input/output isolation has no external earth connection. If there is an
earth connection on the distributor and the external connection of the transmitter is connected to
“protective” earth, the shield of the 2-wire cable may NOT be connected to “protective” earth at the
distributor too.
3-3-3. Installation in: Hazardous Area-Non-Incendive
The EXA ISC202S-N may be installed in a Category 3/ Zone 2/ Div.2 area without the use of safety bar-
riers. Maximum permissible supply voltage 31.5V.
mA
mA
mA
to 2.5 mm (26 to 14 AWG). The glands will form a tight seal on cables with an outside diameter in the
range of 6 to 12 mm (0.24 to 0.47 inches).