Safety glossary, Glossary of safety terms – Banner EZ-SCREEN Safety Light Curtain Systems User Manual
Page 60
page
60
Banner Engineering Corp.
•
Minneapolis, U.S.A.
www.bannerengineering.com • Tel: 763.544.3164
EZ-SCREEN Grid
Instruction Manual
Safety Glossary
ANSI (American National Standards Institute): An associa-
tion of industry representatives which develops technical
standards, including safety standards. These standards
represent a consensus from a variety of industries on good
practice and design. ANSI standards relevant to application
of the EZ-SCREEN System include ANSI B11.1 (mechanical
power presses), ANSI B11.2 (hydraulic power presses), and
ANSI/RIA R15.06 (industrial robots and robot systems).
Blocked condition: A condition of the EZ-SCREEN Grid
System when an opaque object of sufficient size
blocks/interrupts one or more beams of the light grid. When
a Blocked condition occurs, OSSD1 and OSSD2 outputs
simultaneously turn off within the system response time.
Control reliability: A method of ensuring the performance
integrity of a control system. Control circuits are designed
and constructed so that a single failure or fault within the
system does not prevent the normal stopping action from
being applied to the machine when required, or does not
create unintended machine action, but does prevent
initiation of successive machine action until the failure is
corrected.
Designated Person: A person or persons identified and des-
ignated in writing, by the employer, as being appropriately
trained and qualified to perform a specified checkout
procedure.
Diverse redundancy: A design feature in which two
components of different design, running from two different
instruction sets (if programmed components), constantly
check all system components, including each other.
Emitter: The light-emitting component of the EZ-SCREEN
Grid System, consisting of a grid of synchronized modulat-
ed infrared LEDs. The emitter, together with the receiver,
creates a vertical “light grid” used to detect a body or torso
as a person enters a hazardous area.
Final Switching Device (FSD): The component of the
machine’s safety-related control system that interrupts the
circuit to the machine primary control element (MPCE)
when the output signal switching device (OSSD) goes to
the OFF-state.
FMEA (Failure Mode and Effects Analysis): A testing pro-
cedure by which potential failure modes in a system are
analyzed to determine their results or effects on the system.
Component failure modes that produce either no effect or a
lockout condition are permitted; failures which cause an
unsafe condition (a failure to danger) are not. Banner EZ-
SCREEN Systems are extensively FMEA tested.
Forced-guided contacts: Relay contacts that are mechani-
cally linked together, so that when the relay coil is energized
or de-energized, all of the linked contacts move together. If
one set of contacts in the relay becomes immobilized, no
other contact of the same relay will be able to move. The
function of forced-guided contacts is to enable the safety
circuit to check the status of the relay. Forced-guided con-
tacts are also known as “positive-guided contacts,” “captive
contacts,” “locked contacts,” or “safety relays.”
Full-revolution devices: A type of machine drive arranged
such that, once started, the machine can only be stopped
when the full cycle is complete. Examples include positive
key clutches and similar mechanisms. Banner EZ-SCREEN
Systems may not be used with full-revolution devices.
Hard guarding: Screens, bars, or other mechanical barriers
that prevent a person from entering or remaining in the
hazard area undetected.
Internal lockout: A lockout condition that occurs due to an
internal EZ-SCREEN System problem. Indicated by the red
Status indicator (only) flashing. Requires the attention of a
Qualified Person.
Latch condition: The response of the OSSD outputs (they
turn OFF) when an object blocks/interrupts a light beam of
the EZ-SCREEN Grid system operating in Latch mode. A
manual reset must be performed after all objects are
removed (all beams clear) to reset the output latch and
allow the outputs to turn ON.
Lockout condition: A condition of the EZ-SCREEN Grid
System that is automatically attained when the System
detects internal or certain external errors. A lockout
condition causes all of the EZ-SCREEN Grid System OSSD
outputs to turn or remain OFF, sending a stop signal to the
guarded machine. To restore the EZ-SCREEN Grid System to
Run mode, all errors must be corrected and a manual reset
must be performed.
Machine primary control element (MPCE): An electrically
powered element, external to the EZ-SCREEN System, which
directly controls the machine’s normal operating motion in
such a way that it is last (in time) to operate when motion is
either initiated or arrested.
Machine response time: The time between the interruption
by the EZ-SCREEN OSSDs and the instant when the danger-
ous parts of the machine reach a safe state by being
brought to rest.
Glossary of Safety Terms
Terms shown in italics in the definitions below are themselves defined elsewhere in the glossary.