User manual - METER SWE-73-L
4.3.
CONNECTION METHOD
Caution
- Installation should be conducted by qualified personnel . During installation all
available safety requirements should be considered. The fitter is responsible for
executing the installation according to this manual, local safety and EMC
regulations.
- Wiring must meet appropriate standards and local regulations and laws.
- In order to secure against accidental short circuit the connection cables must be
terminated with appropriate insulated cable tips.
- Tighten the clamping screws. The recommended tightening torque is 0.5 Nm.
Loose screws can cause fire or defective operation. Over tightening can lead to
damaging the connections inside the units and breaking the thread.
- In the case of the unit being fitted with separable clamps they should be inserted
into appropriate connectors in the unit, even if they are not used for any
connections.
- If the unit is equipped with housing, covers and sealing packing, protecting
against water intrusion, pay special attention to their correct tightening or
clamping. In the case of any doubt consider using additional preventive
measures (covers, roofing, seals, etc.). Carelessly executed assembly can
increase the risk of electric shock.
Due to possible significant interference in industrial installations appropriate measures
assuring correct operation of the unit must be applied. To avoid the unit of improper
indications keep recommendations listed below.
–
Avoid common (parallel) leading of signal cables and transmission cables together with
power supply cables and cables controlling induction loads (e.g. contactors). Such cables
should cross at a right angle.
–
Contactor coils and induction loads should be equipped with anti-interference protection
systems, e.g. RC-type.
–
Use of screened signal cables is recommended. Signal cable screens should be
connected to the earthing only at one of the ends of the screened cable.
–
In the case of magnetically induced interference the use of twisted couples of signal
cables (so-called “spirals”) is recommended. The spiral (best if shielded) must be used
with RS-485 serial transmission connections.
–
In the case of measurement or control signals are longer than 30m or go outside of the
building then additional safety circuits are required.
–
In the case of interference from the power supply side the use of appropriate anti-
interference filters is recommended. Bear in mind that the connection between the filter
and the unit should be as short as possible and the metal housing of the filter must be
connected to the earthing with largest possible surface. The cables connected to the filter
output must not run in parallel with cables with interference (e.g. circuits controlling relays
or contactors).
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