P
Part-Revolution Clutch
A type of clutch that may be engaged or disengaged
during the machine cycle. Part-revolution clutched
machines use a clutch/brake mechanism, which can
arrest machine motion at any point in the stroke or
cycle.
Pass-Through Hazard
A pass-through hazard is associated with applications
where personnel may pass through a safeguard
(which issues a stop command to remove the
hazard), and then continues into the guarded area,
such as in perimeter guarding. Subsequently, their
presence is no longer detected, and the related
danger becomes the unexpected start or restart of the
machine while personnel are within the guarded area.
Point of Operation
The location of a machine where material or a
workpiece is positioned and a machine function is
performed upon it.
PSDI (Presence-Sensing Device Initiation)
An application in which a presence-sensing device is
used to actually start the cycle of a machine. In a
typical situation, an operator manually positions a part
in the machine for the operation. When the operator
moves out of the danger area, the presence sensing
device starts the machine (no start switch is used).
The machine cycle runs to completion, and the
operator can then insert a new part and start another
cycle. The presence sensing device continually
guards the machine. Single-break mode is used when
the part is automatically ejected after the machine
operation. Double-break mode is used when the part
is both inserted (to begin the operation) and removed
(after the operation) by the operator. PSDI is
commonly confused with "Trip Initiate." PSDI is
defined in OSHA CFR1910.217. Banner safety light
curtain systems may not be used as PSDI devices on
mechanical power presses, per OSHA regulation 29
CFR 1910.217.
Q
Qualified Person
A person who, by possession of a recognized degree
or certificate of professional training, or who, by
extensive knowledge, training and experience, has
successfully demonstrated the ability to solve
problems relating to the subject matter and work.
R
Receiver
The light-receiving component of a safety light curtain
system, consisting of a row of synchronized
phototransistors. The receiver, together with the
emitter (placed opposite), creates a "screen of light"
called the defined area.
Reduced Resolution
A feature that allows a safety light curtain system to
be configured to produce an intentionally disabled
light beam(s) within the light curtain, which increases
the minimum object sensitivity. The disabled beam(s)
appears to move up and down (float) to allow the
feeding of an object through the defined area at any
point without tripping the safety outputs (for example,
OSSDs) and causing a Auto Start/Restart (Trip) or
Manual Start/Restart (Latch) condition. Sometimes
called Floating Blanking.
Reset
The use of a manually operated switch to restore the
safety outputs to the On state from a lockout or a
Manual Start/Restart (Latch) condition.
Resolution
See
Minimum Object Sensitivity
.
S4B Safety Light Curtain
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