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Interlocks are the key to safety

A Rockwell Automation - Allen-Bradley Guardmaster product story

Edited by the Engineeringtalk editorial team Mar 11, 2002

The new Guardmaster-Prosafe range of single- and dual-key trapped-key interlocks have an antitamper mechanism which makes them the most practicable and reliable method of safety power interlocking.

The new Guardmaster-Prosafe range of single- and dual-key trapped-key interlocks have a unique antitamper mechanism which makes them the most practicable and reliable method of safety power interlocking for installations in industrial, process, petrochemical, nuclear, automotive and machine tool environments, where safe entrance to enclosures is required following the electrical isolation of machinery.

Interlocks in the Guardmaster-Prosafe range are offered in single key and dual key access configurations, both of which have unique stainless steel coded keys and barrels to satisfy even the most complicated of interlocking systems.

The units have a direct drive mechanism to give the positive operation described in the "Safety of machinery" standard BS-EN292.

They are CE marked and are fully tested and approved to standards EN1088, IEC 60947-5-1 and GSET19.

In addition to the above approvals, the Guardmaster-Prosafe range is the only one to carry the prestigious BG mark, a sign of safety, independently tested by the German Berufsgenossen-schaftliches Institutfur Arbeitssicherneit, 'BIA'.

Guardmaster-Prosafe single key access units are designed for the interlocking of hatches, guards and doors on machines where full body access is not required.

They are extremely reliable and have the advantage of not requiring electrical wiring to the guard.

With single key access units, the key, after it has been turned to release the guard-locking unit remains trapped and cannot be removed until the guard is closed and locked again.

As a result, it is impossible to open the guard without first isolating the power source, and it is also impossible to switch on power to the machine without closing and locking the guard.

Dual key Guardmaster-Prosafe interlocks are designed for applications where full body access to an enclosure is required.

They can be used in one of two modes: sequential key exchange, with one key in and one out, or dual key insertion with both keys trapped to operate.

In the former mode, one key, the primary, remains trapped after being inserted and rotated.

The secondary key is then inserted and turned, allowing the guard to be opened.

The secondary key can now be removed and used as the next stage of an interlocking sequence, or be retained as a personnel key to ensure that machinery cannot be restarted whilst the key holder is inside the hazard area.

By using a combination of Guardmaster-Prosafe system components, virtually any safety interlocking or operation sequencing requirement can be catered for.

A Guardmaster-Prosafe Key Exchange unit is fundamental in linking together devices in more complex sequences.

It can be mounted at a convenient central point and be used to release multiple keys under preset conditions.

Further details of the new Guardmaster-Prosafe interlocks are contained within the new Guardmaster catalogue.