Detecting Belt Slippage

Don't put a sensor on the belt, put it on the pulley. The pulley will have a shaft that you can put a sensing plate or bolt. If it has a set screw or key, you might be able to use that. If the belt slips the pulses will change in frequency or stop altogether if the belt breaks.

One other method we use in to utilize existing instruments. For example: we have a blower that supplies air to a dryer. The dryer has a pressure transmitter on the hot air inlet ducting. If the pressure dips, we know that the belt is slipping.

Hi, do you need the belt to slip, all v-belts slip, the amount of slip is determined by the condition of the pulleys and belt, also the tension on the belt. But even if the drive was set up perfectly, a wrapped v-belt will still slip about 5-7%.

If you do want slip then use a timing belt, then there will be no slip.

Big Kev.

There are many commercial belt slip detectors available. Turck, Effector and Mann (now a division of Moeller) come to mind. Other means using your PLC (if you have one) are possible, but this is the easiest. All approaches listed utilise prox switches and targets on pulleys.

You can install a zero-speed switch on the driven pulley. There are a few different types, I have used ones from A-B and Electro-Sensors.

You could certainly use prox switches on the driven and drive pulleys (counting pulses and comparing ratio). However, given reasonably good design, the motor will not ordinarily be running at its maximum torque. When something jams, torque will go up dramatically, given a reasonably tight belt in good condition. So if you sense torque, (via amperage draw) you can shut down the motor before belt damage or motor damage occurs.

Ken,

Belt slip protection work for all sources of belt slip which is why we use them on conveyors. Once the belt slips the torque usually decreases particularly when the rubber starts to melt or burn. The electronic shear pin approach seems simple but ends up unreliable in practice.