Grounding the instrument
NOTICE
Star or daisy chain configurations are not allowed under any circumstances.
The LWT must be grounded in accordance with national electrical codes, using a protective earth (PE)
terminal by means of a short connection to an equipotential bonding. The equipotential bonding
conductor must have a maximum cross-section of 4 mm² (12 AWG).
PE terminals are available inside and outside the instrument housing (see Figure 12). Both terminals are
electrically interconnected.
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Figure 12 Position of the two PE terminals
If using the external PE terminal, you must connect the grounding wire to the monitored vessel.
When grounding the LWT with a shielded wire, connect the wire to the PE terminal located inside the
housing. That shielded wire should only be grounded at one end, not both.
NOTICE
The LWT instrument has a ½-inch NPT/M20 cable gland entry.
The most effective way to ground the LWT housing is a direct connection to a ground with a maximum
impedance of 5 mΩ.
Outside installations or installations exposed directly or indirectly to lightning discharges shall have
a secondary lightning protection module. Use of a protected terminal block in combination with a
lightning arrestor module is mandatory for the continuous protection of users and installations.
22
User Guide
Internal PE terminal
External PE terminal