schmersal PSC1-C-10 Series, Руководство по установке

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Installation manual
PSC1-C-10 Installation manual V2.6 Page 60 of 173
Version: 57E
4.2.2.6 Safety-related assessment of the encoder types and their combination
Due to the monitoring functions implemented in the PSC1 series, in applications with encoder systems
there are initially no special requirements on the internal layout of the encoder electronics, i.e. it is
generally possible to use standard encoders.
In general, a safety-related assessment of the overall arrangement is to be undertaken. During this
process the information from the manufacturer of the encoder (PFH, MTTF) as well as the DC from the
tables in 4.2.2.2 are to be used.
On the usage of individual encoders, as a minimum a fault exclusion is required for the mechanical
actuation chain as well as the single-channel part considering the applicable specifications from EN ISO
13849-1. The information in 4.2.2 is also to be followed.
PL d and higher according to EN ISO 13849-1 is in general achieved with a combination of two
encoders with essentially different technology and separate mechanical attachment.
The usage of a compact encoder with internal dual-channel layout with different technology is just as
suitable for applications up to PL e according to EN ISO 13849-1, however considering the specific fault
exclusions required and their admissibility. Generally encoders with proven safety-related properties
should be used for this purpose; their safety level should correspond as a minimum to the level
required.
Safety instructions:
•
The usage of standard encoders or a combination of standard encoders is permissible. A
safety-related assessment is required for the overall arrangement comprising encoders, other
sensors/switching elements for triggering the safety function, the PSC1 module and the
shutdown channel. To determine the safety level achieved, among other data the information
from the manufacturer (PFH, MTTF) and the DC as per the specifications in 4.2.2 is to be used.
•
On the usage of only one encoder, the fault exclusion shaft fracture / fault in the mechanical
encoder connection is required. For this purpose suitable measures are to be taken, e.g.
positive locking of the encoder connection using a slot and key or locking pin. The applicable
information from the manufacturer as well as EN ISO 13849-1 in relation to the requirement
and admissibility of the fault exclusion are to be followed.
•
Preferably, only encoders with proven safety-related properties are to be used as individual
encoders. This encoder's safety level must correspond as a minimum to the safety level
required for the overall arrangement. The instructions from the manufacturer in relation to
diagnostic measures, mechanical connection and measures for the supply of power are to be
followed.
•
SIN/COS encoders: the internal layout of the sensor system must be designed such that the
output signals for both tracks are generated independently of each other and common cause
failures are excluded. In addition, the mechanical layout is to be verified, e.g. fastening of the
code disc to the shaft. Preferably, encoders with proven safety-related properties are to be
used.