Product category:
Machine Safety Components
News Release from: Schmersal UK | Subject: AZ16zi, AZ17zi and AZ20zi switches
Edited by the Engineeringtalk Editorial
Team on 14 March 2000
Safety interlock switch can never be
bypassed
Schmersal (UK) have introduced a new range of safety interlock switches that are activated by an individually-coded, geometrically-unique, actuating key with 15,000 different combinations.
Schmersal (UK) Ltd, specialists in man-machine safety systems, have introduced a new range of safety interlock switches that are activated by an individually-coded, geometrically-unique, actuating key with 15,000 different combinations Conventional safety interlock switches are only available with a standard key (actuator), designed to prevent the guard switch being bypassed using screwdrivers, paperclips and other objects
This article was originally published on Engineeringtalk on 30 May 2000 at 8.00am (UK)
Related stories
Light barriers take on space limitations
Schmersal (UK) Ltd, specialists in man-machine safety systems, have introduced the SLC400 range of optoelectronic safety light grid barriers and curtains, designed to guard plant and machinery
Bus-capable safety systems for mobile cranes
For mobile crane manufacturer Liebherr, data bus technology offers significant advantages. As well as providing vital bus-capable components, Schmersal was involved in the design of a bus system too.
However, these switches can be bypassed using a similar standard key obtained from another machine or from the stores department.
This practice is particularly common in plants where a large number of machines are fitted with the same type of switch.
Schmersal individually-coded, safety interlock switches represent a new generation of mechanical guard switches.
Further reading
Working safely with machines
In this article Terry Hayward, general manager of Schmersal UK Ltd, discusses man-machine safety and the options available.
A safety guard door handle which is easier to use
Schmersal (UK) have introduced a safety guard door handle with an integral unlock button, designed to simplify machine guarding operations without affecting operator safety
And with 15,000 key combinations available, engineers can now specify a switch, safe in the knowledge that it can never be bypassed with a key from another machine.
The tamper-resistant design includes non-removable actuating heads and high-strength stainless steel keys that tolerate mechanical abuse without damage.
The three versions available - AZ16zi, AZ17zi and AZ20zi - are designed for use as safety interlocks on moveable machine guards which, when open, expose operators or maintenance personnel to machine hazards.
Typical applications include protective gratings, hinged or swiveling covers, access panels and other types of moveable guards.
An IP67 rating also makes the switches ideal for hostile environments.
All versions are of two-piece design, consisting of a switch mechanism and an individually-coded actuator key that is hard-mounted directly to the moveable guard.
When the guard is opened the normally-closed (NC) contacts are forced to open through a direct mechanical linkage with the key.
The positive-break NC contacts ensure that, when the key is removed, the circuit is interrupted and the machine is stopped.
When the guard is closed the key forces the NC contacts to re-close and NO contacts to re-open.
The switches are also available in 3 pole versions with one normally open and two normally closed.
This gives greater flexibility because two contacts can be connected directly to an appropriate safety relay with the third available as a signaling contact.
To allow flexibility when installing the switches, four key entry locations are available on the AZ16zi and AZ17zi, and two are available on the AZ20zi.
The AZ20zi also features high-speed key withdrawal.
All switches meet stringent international safety standards including BG, UL and CSA.
• Schmersal UK: contact details and other news
• Email this article to a colleague
• Register for the free Engineeringtalk email newsletter
• Engineeringtalk Home Page
Search the Pro-Talk network of sites
