Banner SI-HG63 Hinge Style Switches - Manual (Page 9)

When multiple safety interlock switches are series connected, the failure of one switch in the system may be masked or not be detected
at all. The following two scenarios assume two positive-opening safety interlocking switches on each guard, both connected in series to
switches of a second guard (dual channel hookup) and monitored by a safety module or safety controller:
• Masking of a failure—If a guard is opened but one switch fails to open, the redundant safety interlocking switch on that guard opens
and a protective (safety) stop occurs. If the faulty guard is then closed, the module/controller will not reset because one channel did
not open, thus complying with the required fault detection. However, if a second "good" guard is cycled (opening and then closing
both of the channels), the failure appears to be corrected (input requirements satisfied) and the module/controller allows a reset. This
system is no longer redundant and, if the second switch fails, may result in an unsafe condition (the accumulation of faults resulting in
loss of the safety function).
• Non-detection of a failure—If a functional guard is opened, both channels open and the module/controller initiates a protective
(safety) stop. If a guard with a faulty safety interlocking switch is then opened and closed before the good guard is re-closed, the
faulty switch is not detected. The system is no longer redundant and may result in a loss of safety if the redundant switch fails to open
when needed.
The system in either scenario does not inherently comply with the safety standard requirements of detecting a single fault and preventing
the next cycle (not a Category 4 application per ISO 13849-1). In multiple-guard systems using series-connected safety interlocking
switches, it is important to periodically check the functional integrity of each interlocked guard individually. Open and close each guard
separately while verifying that the machine properly responds. Operators, maintenance personnel, and others associated with the
operation of the machine must be trained to recognize failures and be instructed to correct them immediately.
WARNING: Series Connection of Safety Interlock Switches
Monitoring multiple guards with a series connection of safety interlock switches may result in a failure being
masked or not detected at all. When such a configuration is used, periodic checks must be performed regu-
larly to verify proper operation. All failures must be immediately corrected (for example, immediately replac-
ing a failed switch), or the loss of the safety stop signal or an inappropriate reset may lead to serious injury
or death.
Maintenance
Checkout
At switch installation or replacement and at machine set up, a Designated Person 2 must test each switch for proper machine shutdown
response and check the switch(es) and installation for proper operation, physical damage, mounting (looseness), and excessive environ-
mental contamination. This must also take place on a periodic schedule determined by the user, based on the severity of the operating
environment and the frequency of switch actuations. Adjust, repair, or replace components as needed. If inspection reveals contamina-
tion on the switch, thoroughly clean the switch and eliminate the cause of the contamination. Replace the switch and/or appropriate com-
ponents when any parts or assemblies are damaged, broken, deformed, or badly worn; or if the electrical/mechanical specifications (for
the environment and operating conditions) have been exceeded. Always test the control system for proper functioning under ma-
chine control conditions after performing maintenance, replacing the switch, or replacing any component of the switch.
Repairs
Do not attempt any repairs to the safety interlocking switch. It contains no field-replaceable components. Return it to Banner
Engineering for warranty repair or replacement.
Contact Banner Factory Application Engineering. They will attempt to troubleshoot the system from your description of the problem. If
they conclude that a component is defective, they will issue a return merchandise authorization (RMA) number for your paperwork, and
give you the proper shipping address.
Important: Pack the safety interlocking switches carefully. Damage which occurs in return shipping is
not covered by warranty.
2 A Designated Person is identified in writing by the employer as being appropriately trained to perform a specified checkout procedure.
Hinge Wing Safety Interlock Switches
Datasheet
129465_web Rev.
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