W.E.ST. PQ-132-U, Technical Documentation Manual

Page: 10 / 34

Page 10 of 34 PQ-132-U 05.06.2020
3 Use and application
3.1 Installation instructions

This module is designed for installation in a shielded EMC housing (control cabinet). All cables which
lead outside must be screened; complete screening is required. It is also necessary to avoid strong
electro-magnetic interference sources being installed nearby when using our open and closed loop
control modules.

Typical installation location: 24 V control signal area (close to PLC)
The devices must be arranged in the control cabinet so that the power section and the signal section
are separate from each other.
Experience shows that the installation place close to the PLC (24 V area) is most suitable. All digital
and analogue inputs and outputs are fitted with filters and surge absorbers in the device.

The module should be installed and wired in accordance with the documentation bearing in mind EMC
principles. If other consumers are operated with the same power supply, a star-shaped ground wiring
scheme is recommended. The following points must be observed when wiring:

The signal cables must be laid separately from power cables.

Analogue signal cables must be screened .

All other cables must be screened if there are powerful interference sources (frequency
converters, power contactors) and cable lengths > 3 m. Inexpensive SMD ferrites can be
used with high-frequency radiation.

The screening should be connected to PE (PE terminal) as close to the module as
possible. The local requirements for screening must be taken into account in all cases. The
screening should be connected to at both ends. Equipotential bonding must be provided
where there are differences between the connected electrical components.

If having longer lengths of cable (> 10 m), the diameters and screening measures should
be checked by specialists (e. g. for possible interference, noise sources and voltage drop).
Special care is required if using cables of over 40 m in length, and if necessary the
manufacturer should be consulted if necessary.

A low-resistance connection between PE and the mounting rail should be provided. Transient
interference is transmitted from the module directly to the mounting rail and from there to the local
earth.

Power should be supplied by a regulated power supply unit (typically a PELV system complying with
IEC364-4-4, secure low voltage). The low internal resistance of regulated power supplies gives better
interference voltage dissipation, which improves the signal quality of high-resolution sensors in
particular. Switched inductances (relays and valve coils) which are connected to the same power
supply must always be provided with appropriate overvoltage protection directly at the coil.