Jemtech’s safety switches use technology similar to RFID with a reader in the switch body and an active transponder tag in the switch key.
The new line of high sensitivity safety switches incorporates larger antenna coils in the switch and key. The larger area of these coils allows for much greater misalignment of the pair. In some applications, this misalignment is inherent in the plant, and the greater sensitivity in the switches is very beneficial.
The coils allow sensing distances of more than 50mm face-to-face at misalignments of more than 30mm in any direction off centre. Misalignment of up to 65mm off centre is tolerated at sensing distances of 30mm or less.
The upgraded device has been used to detect the safe positioning of overhead gantry cranes. These cranes use automated positioning, but with the various mechanical tolerances in the positioning, it is necessary to have the high sensitivity available in these devices.
Other applications include conveyor systems, trolley position sensing and applications where the moving plant has wide tolerances in the safe parked positions.
High sensitivity safety switches are designed with polyurethane plastic outer housings and polyurethane rubber encapsulation. Available with cable tails or IP68 plugs as options, the safety devices can be used in hose-down, condensing and corrosive atmospheres. There are no cavities in the housing or moving parts.
The safety switches use dual redundant microprocessor channels as well as dual receivers to ensure that failure of any part of the device can be detected at or before the next safety demand. This is a key advantage over mechanical switches that cannot detect failure until the switching demand and may have to be duplicated in some applications to provide sufficient safety.