Grounding - ABB LWT300 series User Manual

ELECTROSTATIC DISCHARGES
Before performing any connection, operators shall make sure that they have discharged
all static electricity from their body before touching electronic components.
• All connections must be established in a de-energized state.
• Before installing the instrument, make sure that the appropriate supply voltage is available.
• The power supply shall be equipped with short circuit protection and auto restart functions.
• For continuous installation protection, a double insulation power supply (5 kV or higher) shall be
used for the current loop.
• In an industrial environment where EMIs (electromagnetic interferences) are extremely present (e.g.,
rock quarries, mines, large chemical plants, etc.), ABB recommends the use of noise filters on the DC
power supply to the instrument and on signal isolators' 4 – 20 mA output.
• Instruments will not work if exposed to common mode voltages in excess of the maximum allowed
supply voltage.

Grounding

• Ground the instrument according to requirements (see "Grounding the instrument" on page 22).
WARNING
Ensure that the equipment or any device or power cord connected to the instrument
is properly grounded.
If an interruption of the protective earthing connection is suspected, make sure that
the equipment is not used. All protective earthing connections (grounding) must be
active at all times. The absence of grounding can lead to a potential shock hazard that
could result in serious personal injury.
Use the instrument only if a properly grounded power source is available in
accordance with the local electrical code.
• To avoid injury or property damage in external installations exposed to lightning, a transient voltage
suppression module or galvanic isolator shall be installed, with proper grounding, before entering a
building with a cable. Refer to local building and electrical codes for proper practices.
NOTICE
The presence of noise on the instrument 4 – 20 mA output can be a sign of poor or
intermittent grounding, insufficient cable shielding, or noisy power line in the vicinity.
4
User Guide