P
14 Posts in this encyclopedia categoryPerformance Level (PL)
Discrete level for safety-related performance. PL "a" is the lowest, PL "e" the highest level. [EN ISO 13849-1]
Periodic test
The periodic test for ESPE type 2 simulates the response of the
sensor part in order to detect a dangerous failure. It is prescribed for
the verification of the function of ESPE type 2 according to EN 61496-1
and is carried out by the SAG connected to the sensor.
Plastic housing
See electronics enclosures, control cabinet enclosures, distribution enclosures.
Position monitoring
Monitoring the position of a safety guard (e.g. safety door) with the aid of suitable signal transmitters and evaluation unit.
Position switch
Position switch is part of the interlocking device of a guard. It
changes its switching state depending on a mechanically given control
command. There are position switches without and with guard locking
(guard locking device).
Probability of Failure dangerous per Hour (PFHd)
Probability of Failure dangerous per Hour or probability of a
dangerous failure per hour. The failure limit value PFD is determined
for small demand rates, while the failure limit value PFH applies to
large or uninterrupted demand rates.
Probability of Failure on Demand (PFD)
Probability of Failure on Demand or average probability that the safety function will not be executed on demand.
Protection class
Standardised classification of the protection of a device against
contact, foreign bodies and water. According to IEC/EN 60529, the degree
of protection is indicated by the code letters IP and two code numbers.
The first code number describes the protection against contact and
foreign bodies, the second code number the protection against water.
Proximity Devices with defined behaviour under Fault conditions (PDF)
PDF is a proximity switch for safety functions with defined behaviour
under fault conditions (PDF), in which a switching operation is
triggered by a change in optical, magnetic, electrostatic, acoustic or
other fields. The generated switching signal may be used for
safety-relevant controls of machines.
Proximity switch
Proximity switches (inductive, optical or capacitive) change their
switching state when bodies or liquids approach. They are predominantly
equipped with semiconductor outputs.
Pull-wire switch
Rope pull switch causes a stop category 0 when a ripcord is pulled or the rope breaks.
Push-button monitoring
The function of the push-button is monitored by a dynamic signal change when the push-button is released.This
prevents, for example, the system from being switched on, which would
be caused by a short-circuited push-button (e.g. due to manipulation or a
short circuit).