Electronic shaft speed monitoring

Motion Control & Drives

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August 2009 Motion Control & Drives

Speed monitoring of driven machinery is quite common. In multiconveyor systems, for example, it can be disastrous if conveyor A stops and conveyor B does not. There is a trend to replace mechanical speed switches with electronic devices, which is quite simple once some application pitfalls have been overcome. The current speed monitor range from Synatel addresses these problems to provide users with trouble free electronic speed monitoring solutions.

Sensing

Synatel’s PU1DR speed monitor is a complete integrated device in a DIN package. Totally sealed – calibration is achieved magnetically – the unit is designed to provide a fixed 80% under-speed alarm with appropriate time delay. All that is required to set the unit is to apply the calibration magnet at the same time that the machinery is started. This has two effects:

* The normal running speed is established, and the 80% set-point calculated.

* The normal run-up time is established.

The PU1DR accepts power supplies from 12-240 VDC and 24-240 VAC. It is provided with an SPDT relay output for alarm purposes. A two wire version is available in an M30 package.

Installation is the difficult part

A typical installation requires a suitable target, a mounting bracket for the sensor and a safety guard for protection. Synatel has introduced its Whirligig which integrates all these functions in a single package to make things simpler. The Whirligig is fitted to the end of the shaft to be monitored by means of an M12 stud at the rear centre of the round housing. Inside this housing is a multiblade rotor designed to generate 2, 4 or 8 pulses per revolution. A mounting position is provided for the PU1DR, or similar sensor, and adaptors are available for standard M30 proxies. A flexible tail is provided to anchor the assembly to the stationary surround structure.

Magmount is even easier

The use of the Whirligig requires that the shaft to be monitored be drilled and tapped M12 for mounting which can on occasions prove to be troublesome. Magmount overcomes the problem. The Magmount consists of a steel boss drilled M12 to accept the stud on the Whirligig and backed with a super-magnet. The magnet then clamps to the end of the shaft and the assembly is completed in seconds.

The Magmount is of course not suitable for stainless steel shafting.

For more information contact Rod McLeman, Blanes Pressure Solutions, +27 (0)11 422 1749, [email protected], www.pressuresolutions.co.za

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