Product category:
Machine Safety Monitoring and Control
News Release from: Rockwell Automation | Subject: Self Monitoring Contact Block
Edited by the Engineeringtalk Editorial
Team on 17 July 2001
Extra safety from self-monitoring switch
contact
A new Self Monitoring Contact Block for use with the Allen-Bradley 800E pushbutton range features a patent pending design to monitor its installation to the emergency stop actuator
Rockwell Automation introduces the innovative, Allen-Bradley Self Monitoring Contact Block for use with the Allen-Bradley 800E pushbutton range Designed to provide enhanced protection to all installations, particularly safety critical or process applications, the new contact block features a patent pending design to monitor its installation to the emergency stop actuator
This article was originally published on Engineeringtalk on 8 Aug 2008 at 8.00am (UK)
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The unique contact block comprises a set of self-monitoring, early make, normally open contacts, which close automatically when the block is correctly installed on the actuator.
These contacts are wired in series with the standard normally closed contact and this arrangement eliminates the concerns associated with a damaged or incorrectly installed contact block.
Correct installation of the contact block is vital if the normally closed contacts are to be opened on operation.
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If the block is damaged or becomes detached, the contacts may not open no matter how hard or often the actuator is operated.
There is often no advance warning of this condition since the contact block cannot be seen at the rear of the control panel.
Clearly the safety implications for the plant and personnel could be very serious.
Using the new Allen-Bradley Contact Block ensures that if it becomes separated from the actuator, the circuit is interrupted by the self- monitoring, normally open contact.
This prevents operation of the equipment and immediately alerts the operator to the fault condition.
When the block is correctly installed, only the operation of the actuator will break the circuit through the normally closed contact.
There are a variety of circumstances that may result in contact blocks becoming separated from the actuator.
For example, a contact block latch may not have been secured correctly following maintenance or a machine upgrade, or it may have been damaged during routine maintenance work.
Alternatively, the cause could be excessive vibration over a long period or wiring that does not have adequate slack.
On installations where the safety or cost implications associated with an emergency stop pushbutton failing to stop equipment could be disastrous, the new Allen-Bradley Self Monitoring Contact Block removes these unknown factors and provides the ultimate solution.
They are low cost, quick to install, and can be retrofitted to existing installations.
The Allen Bradley 800E range of Emergency Stop operators comprises 30mm, 40mm and 60mm units with plastic or metal bodies.
When combined with the Self Monitoring Contact Block they provide the highest level of protection to personnel and equipment. Request a free brochure from Rockwell Automation ...
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