Product category:
Machine Safety Monitoring and Control
News Release from: Schmersal UK | Subject: BNS-AES coded door guarding system
Edited by the Engineeringtalk Editorial
Team on 27 September 2004
Coded system guards up to 20 doors
Compatibility problems are claimed to be a thing of the past with the latest BNS-AES coded door guarding system from Schmersal.
Compatibility problems are claimed to be a thing of the past with the latest BNS-AES coded door guarding system from Schmersal As Schmersal's Steven Hill explains: "Matching safety sensors to relay modules can lead to problems if the units selected don't have the correct current and voltage input restrictions on the safety relay"
This article was originally published on Engineeringtalk on 14 Mar 2000 at 8.00am (UK)
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"Problems are caused by high input currents being switched through the reed contacts when the safety guard is closed".
"The excessive current, which may be caused by a high input capacitance on the connected control module, can lead to the NC contact of the safety sensor welding closed".
The Schmersal system, which can be used to guard a single door to Control Category 4 or up to 20 doors to Control Category 3, consists of matched BNS safety sensors and AES modules - and every system selected is approved by the German notified body BG to ensure that components are compatible with, and suitable for, the relevant safety function.
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The noncontact BNS coded sensors, which are completely encapsulated and have an ingress protection rating of IP67, are designed to meet the increasing demands for safety sensors to withstand harsh environments and conditions.
The high degree of sealing is ideal for applications where machine wash down or the prevention of dust or powder ingress is an important requirement, and the smooth wipe clean surfaces also make BNS sensors ideal for the food and beverage industries.
The system's coding is operated by a special magnetic field with a specific polarisation and field strength that is applied to switch the reed contacts.
The precise arrangement of the reed contacts within the safety switch has been selected so that the contacts only change state when a unique magnetic field is present.
The BNS coding system prevents manipulation by standard magnets and the versatility of the sensor itself means it can be mounted behind stainless steel panels to prevent tampering by machine operators.
The noncontact BNS design, which can be fitted to virtually any profile and surface, also provides greater tolerance for actuator and sensor alignment than fixed mechanical switches with separate actuators, which can in time suffer from misalignment problems.
The system's small physical size is particularly suited to monitoring small guard doors and entry flaps requiring small actuating radii that can be hard to achieve with larger mechanical switches and actuators.
The BNS-AES system consists of a magnetic safety switch, actuator and safety module.
The range is capable of monitoring a single guard door to EN954-1 Control Category 4 or up to 20 doors to EN954-1 Control Category 3.
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