DKS PD96, Руководство пользователя, Страница: 11 / 57

User manual for meter with U/I input PD96
11
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
protectionsystems, 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 interference from the power supply side the use of appropriate
antiinterference 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).
Connection of the power supply, and the measurement and controlling signals should
be made by screw connectors mounted inside the housing.
Figure 4.2. Mehtod of cable insulation replacing and cable terminals
All connections must be made while power supply is disconnected !