Electromechanical switch-operated guard locking meets transponder-coded safety engineering

April 10, 2015
“You can put the actuator in any of the four directions, and you don’t even have to rotate it.”

The CTP series solenoid locking safety switch from Euchner can be used to monitor the position of movable machine guarding by means of inductive coding. These safety systems are designed for use in areas where tamper-resistant safety is required. The CTP features a narrow profile, thermoplastic housing, an inductive read head with integrated evaluation module and a digitally coded actuator.


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The safety switch CTP combines electromechanical safety-switch-operated guard locking or guard-lock monitoring with transponder-coded safety engineering. The transponder technology allows a single CTP to achieve Category 4 PLe, according to EN ISO 13849-1, without additional fault exclusion. “Many of our safety switches have the integrated evaluation built-in,” explains Mark Czapla, electrical engineer, Euchner USA. “It doesn’t require external modules. Coming out of the switch, you have two safety PNP signals, similar to a light curtain. With this switch, you can chain up to 20 switches together and retain PLe and Category 4, with a single output connection to a safety PLC or safety system control.”

The CTP also exceeds the requirements in EN ISO 14119 for a Type 4 switch with a high coding level. It’s designed for applications in which a high performance level and a locking force of up to 2,500 N are required.

“Anybody who has any of our TP or STP and who requires multiple switches on a door or a guard can put this on instead and have the same level of protection using this single item,” says Czapla. “One CTP guard can replace two of the others. The CTP is design for any type of people protection where you have stored energy hazards, specifically anywhere you have a switch and you want it to be very difficult to bypass.”

Also read: Consider the need for safety switches

The CTP is equipped with a diagnostic function, and an LED indicator is integrated on the front panel so the device status is immediately apparent. With the CTP, it’s also possible to connect monitoring outputs and a diagnostics output directly to the PLC. Depending on the version, the CTP is also suitable for direct connection to safe control systems or for the series connection of up to 20 devices.

“The switch is only going to respond to the actuator to which it was installed,” explains Czapla. “You can’t just use any mechanical switch. It’s much more difficult to bypass. The new design of the head is different, too, in that it will work in all four directions for the actuator. It’s a little more forgiving. Many years ago, they created a part number for each of the four directions. You’d need four times as many part numbers. It’s a bookkeeping or inventory issue. Now you don’t have to do that. You can put the actuator in any of the four directions, and you don’t even have to rotate it.”

The narrow design of the CTP makes possible straightforward and space-saving mounting on the safety guard. The plastic housing with metal head and IP 69K protection are designed to give the CTP application flexibility.

“It’s Unicode,” says Czapla. “It could be used in machine tools, grinders, processing robotics, and all kinds of dangerous machinery you want to keep employees away from while they’re running. Unicode has been on all of our RFID safety switches for years. The IP69K rating means it can be used where you have food-grade applications you need to wash down. It’s made to withstand the washing and harsh chemicals.”

More on the CTP series solenoid locking safety switch

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About the Author

Mike Bacidore | Editor in Chief

Mike Bacidore is chief editor of Control Design and has been an integral part of the Endeavor Business Media editorial team since 2007. Previously, he was editorial director at Hughes Communications and a portfolio manager of the human resources and labor law areas at Wolters Kluwer. Bacidore holds a BA from the University of Illinois and an MBA from Lake Forest Graduate School of Management. He is an award-winning columnist, earning multiple regional and national awards from the American Society of Business Publication Editors. He may be reached at [email protected] 

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