Function Description; Integrated Protection Mechanisms - Pilz PNOZ ma1p Operating Manual

Function Description

4 Function Description
4.1

Integrated protection mechanisms

The relay conforms to the following safety criteria:
The circuit is redundant with built-in self-monitoring.
}
The safety function remains effective in the case of a component failure.
}
The analogue input module can be used for applications up to SIL3.
For applications in accordance with SIL2 or SIL3, input devices must be attached that are
certified for SIL2 in accordance with IEC 61508. The output signal of the input device must
be monitored, i.e. actual and set value must be compared with one another. In the event of
a deviation, a reaction must occur that the PNOZmulti recognises and to which it reacts.
SIL2 applications:
}
SIL2 applications are only possible for current measurement. If the analogue input
module is to be used for current measurement on SIL2 applications, both inputs can be
used independently for current measurement.
SIL3 applications:
}
If the analogue input module is to be used for SIL3 applications, both inputs must be
configured. They will then be combined to form a SIL3 input. To do this, connect a suit-
able encoder to each input. The analogue input module will then check the feasibility of
the input signals, i.e. the values measured from both input signals are compared.
Operating Manual PNOZ ma1p
21687-EN-04
NOTICE
For SIL3 applications, set a maximum permitted deviation between the
measured values of both input signals (tolerance) in the PNOZmulti Config-
urator. A tolerance is only entered to balance out the imprecision of the sig-
nal recording, the encoder and the analogue input module. To maintain
safety, the tolerance should be set as low as possible. Please note that the
maximum safety-related measurement error for the overall system is
composed of the following measurement errors:
Error during signal recording
+ Sensor measurement error
+ Max. measurement error in the event of a potential module error
To ensure that your application switches off safely in the event of a critical
process variable, the configuration of the range limits/threshold values must
be increased/decreased to take into account the maximum measurement
error.
11