"Loss of Motion" Detector for Rotary Heat

Are you trying to detect the belt's motion or the drum's motion? What is the belt's compostion and also the drum? Does the belt drive idler rollers as it moves? Is this an operator error? What if the belt stops moving and you successfully detect it, what action would be taken? Is the damage already done? If so, you may need to interlock the belt controls to some temperature controls.

Seems like it would be worth the cost to replace the belt with a chain drive.

Add a pulse wheel to the motor drive pulley. Calibrate it to the standard running rpm of the motor. Use a hall effect sensor to detect the motion of the pulse wheel. When the speed drops below a threshold value cut the current to the heating elements and begin a timed shut down of the belt drive so that the drum continues to turn until the surface temp is well below the danger point. You might want to consider installing an emergency power supply that continues to turn the motor in event of power loss so that the material in process as well as the belt suffer minimal damage.

Belt slip, underspeed and zero speed sensing is standard in the materials handling industry (Conveyor belts etc.) Any of the automation and control companies have the necessary hardware for a variety of regimes. For a starting point try Schnieder Electric, also companies such as Turck and Effector.

This is Greg Again,

I guess I forgot to include some information:

- we don't care about whether the drive is turning or not (yes, it is chain driven variable). That is not where the problem is really.

- we need to attach an alarm to a "loss of motion" sensor of some sort so that people in the neighboring department can go and fix the problem (the department that uses this machine works different hours and they leave with the heating elements turned off, but the belt must remain turning to dissapate heat and keep things from burning while it cools down. Therein lies the problem...as the temperature drops, that is when the belt might be too "stretched" -for lack of a better word- from the previous heat and may lag and just sit on the drum and shafts while the motor still turns.)

We need something self-contained that actually has contact with the belt itself to see if the BELT stops turning.

Thanks again

Greg

Sounds like an application for a zero motion sensor....many out there, check http://www.ssac.com/standard/ff-md1.htm for applications I've also had success with Rayteck's small infrared temperature sensor...reliable in a hot and dirty environment...if monitoring temperature of the belt or drum is a concern...

Actually spelled "Raytek"...sorry

My 'Laser Mouse' is fairly good at detecting motion. I looked at hall effect sensors, they mostly seem to have a max operating temp of 150C or 302F. might be a problem? An indellible black laundry marker pen might be useful, making a sort of uniform 'bar code' at the edge of the belt? An optical sensor could detect motion.

What you need is an automatic belt tesioner. It is self evident that the drum diameter will shrink as it cools and the belt can start slipping. A tensioner will compensate for this. I would also look into driving the tail pulley with a sincronized drive or if not sincronized use overruning clutches on both drives. That might also work. But the tensioner is the least expensive and simplest solution. CsMFarkas

If you want to sense motion Keyence has some innovative and cost efficient systems that come with Alarms. If your looking to have someone else figure it out for you try ATS Automation Tooling Systems out of Cambridge, Canada. Huge expertise in automation. They can make it stop on its own.