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MAN0530 Issue 15 - 07/17
2104M0506
3. INSTALLATION AND OPERATION
3.3 ELECTRICAL CONNECTIONS
3.3.1 General
All ranges of Searchline Excel comply with the EMC requirements EN50270. In order to
maintain compliance with these standards it is essential that the electrical installation of Excel
is engineered correctly.
Electrical installation standards vary for different countries, companies and applications and it
is the responsibility of the installation design authority to determine the applicable standards
and ensure compliance with them. When designing electrical installations for Excel, Honeywell
Analytics recommend that the installation design authority considers the following:
Any earthing regime employed must avoid earth loops.
The following information is provided to assist with proper earthing of Searchline Excel:
• Searchline Excel has an earth wire (green and yellow) for connection to protective earth.
This is connected to the enclosure and isolated from the other wires. Maximum voltage
between earth and the other wires is 350 V.
• There is an earthing point on the outside of the Searchline Excel enclosure for connection
to protective earth.
• Searchline Excel does not require an "instrument earth" connection.
In addition, consider the following points:
General recommendations
1. In general, correctly engineered star earthing arrangements minimise earth current crosstalk
and noise, improving the reliability and performance of instrumentation.
2. The use of a single, screened / shielded cable for each field device ensures good screening
/ shielding and reduces crosstalk.
Field Cabling
1. The entire length of the field cabling connected to a unit should be screened / shielded.
The screen / shield should be connected to a low noise instrument earth at one end.
2. The screens / shields of field cabling must not be connected in a manner that creates earth
loops or that will result in the screens / shields carrying large currents from heavy plant or
equipment.
3. If armoured cable is being used it is necessary to prevent the armour becoming connected
to the screen / shield.
4. For installations where the field cable conductors run through conduit or armour connected to
protective earth, the conduit or armour should not be considered as a sufficient screen /
shield. A separate cable screen / shield, connected to a low noise instrument earth should
be employed.
5. The field cabling conductors should have sufficient cross sectional area to ensure that the
minimum supply voltage at the field device is 18 Vdc.
18
Searchline Excel
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