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Feedback: Monitoring of pneumatic
and manual valves must be possible.
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- For all actuators according to VDI / VDE 3845.
- Valve position visible via target pucks / switching cams.
- AS-i dual sensor for quick and safe installation due to ”plug & play”.
- Also available as complete set incl. all the accessories for a valve.
- High machine uptime: long-lasting and maintenance-free products.
Introduction
In industrial processes where liquids, air or gases are used valves are needed for dosing and control. There is a wide variety of valve types; butterfly or ball valves being the most common quarter-turn types. These valves are seldom operated manually. Pneumatic valve actuators are normally used for mechanical positioning. The valve position must be monitored electronically. Mechanical switches are still often used for position feedback on the actuator shaft. For other solutions several proximity sensors are used together with a switch target for position detection. Disadvantage: Mounting is mechanically complex. During switch mounting the signal wires can be reversed when they are connected in the top-mounted junction box. Where there are temperature fluctuations condensing humidity leads to corrosion and thus malfunction.
Operating principle
An innovative design eliminates the disadvantages of these conventional solutions. In 1992 ifm electronic developed a standard which is now used by many leading actuator manufacturers. A round switch target, known as a ”puck”, with two metal screws offset by 90° is mounted on the actuator shaft. The screws are located at a different height. A compact dual proximity switch (type IND) with two integral sensors detects the upper or lower metal screw depending on the valve position and thus the two switch positions.
Due to the simple construction the system operates safely with no wear at all. It is virtually resistant to external influence and meets the protection rating IP 67. Under certain conditions the unit can even be self-cleaning. The sensors are also resistant to mechanical stress such as vibration and shock.
Special design AS-i (T5)
An extended design is the series T5. In addition to the inductive dual sensor, the unit provides an integrated connection for the solenoid valve. The connection to the control unit is made via a two-wire AS-i cable.
The asset:
Up to 30 other units can be connected to this line and separately controlled via the AS-i master.
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