TMT142 HART® Wiring
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3.3 Shielding and potential equalization
Please take note when installing the device:
If screened (shielded) cables are used then the shielding connected to the output (output signal
4 to 20 mA) must be at the same potential as the shielding at the sensor connection!
When operating in plants with high electromagnetic fields, it is recommended that all cables be
shielded using a low ohm ground connection. Due to the possible danger of lightning strikes,
shielding is also recommended for cables that are run outside buildings!
3.4 Degree of protection
The device conforms to the requirements to IP67 ingress protection. In order to fulfill an IP67
degree of protection after installation or service, the following points must be taken into
consideration:
• The housing seals must be clean and undamaged when inserted into their grooves. The seals
must be dried, cleaned or replaced if necessary.
• All housing screws and screw caps must be firmly tightened.
• The cables used for connection must be of the correct specified outside diameter (e.g. M20 x
1.5, cable diameter from 8 to 12 mm; 0.315 to 0.47 in).
• Firmly tighten the cable gland (Fig. 4).
• The cables must loop down before they enter the cable glands (“water trap”, Fig. 4). This
means that any moisture that may form cannot enter the gland. Install the device so that the
cable glands are not facing upwards.
• Cable glands not used are to be blanked off using the dummy plugs provided.
• Do not remove the grommet from the cable gland.
A0024523
Fig. 4: Connection hints to retain IP67 protection
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