Product category:
Machine Safety Components
News Release from: Rockwell Automation (Allen-Bradley Guardmaster ) | Subject: Solenoid key release units
Edited by the Engineeringtalk Editorial
Team on 12 April 2002
Solenoid release units ensure electrical
isolation
Guardmaster Prosafe's new solenoid key release units can be incorporated into virtually any process or access control system to ensure its safe operation.
Guardmaster Prosafe's new solenoid key release units can be incorporated into virtually any process or access control system to ensure its safe operation Ruggedly constructed from 316L stainless steel, the key release units ensure the electrical isolation of machinery, allowing safe access into machine enclosures
This article was originally published on Engineeringtalk on 17 Jul 2008 at 8.00am (UK)
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Although designed primarily for use with Guardmaster Prosafe's mechanical key interlock systems, the single or multiple direct-drive solenoid key release units can also be used in conjunction with other control equipment such as PLCs, or with dedicated stop motion or failsafe timers on machines with run down cycles.
Moving machinery such as food processing, packaging machines and robot welding lines are particularly dangerous and in these applications the use of the key release unit with a dedicated timer can help to ensure that all movement has stopped before the operator can enter the enclosure.
The key to the greater safeguarding provided by the solenoid release unit is a design that allows a trapped key to be removed only when a signal is given to an internal solenoid locking mechanism.
Further reading
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On receipt of this signal the previously trapped key can be removed and used in the next sequence of operation.
This could be to provide access to a gate, or gates, directly, or more often to initiate a further operation, such as the release of multiple keys in a key exchange unit.
In all cases, however, once the key is removed - as indicated by an LED on the unit's front panel - the solenoid cannot return to the locked position even if power is removed.
As an added safeguard, the position of the solenoid is monitored via a positively driven contact ensuring that, in the unlikely event the solenoid fails to re-lock the key, it is impossible for the machine to start up.
Manufactured 316L stainless steel, and equipped with a dust cap as standard, the key release units are built to withstand the harsh conditions encountered in processing and automation applications.
They have a direct drive mechanism to give the positive operation described in the "Safety of machinery" standard BS EN 292, are CE marked and are fully tested and approved to standards EN1088, IEC60947-5-1 and GSET 19.
Available in single or multiple (three or four) key configurations, the key release units are supplied with 24V DC, 110V AC/DC or 230V AC rated solenoids and easy to clean replaceable code barrels.
The latter feature means that new keys can be introduced into the system quickly, should the original ones be lost, removing the requirement to keep a complete set of spare keys.
(This was Engineeringtalk's Top Story on 11 April 2002).
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