Furnace fan shaft rotation detection

[oldpilot]

Hello All;
Would anyone know the best way to verify shaft
rotation when this furnace is in operation? If the
belts brake on the 1 15/16 dia fan shaft the load is
scrap. I need some kind of warning system for the
operator. I was considering a two piece shaft collar
around the shaft with a 1/2 inch dowel pin sticking out
about 2 inches and a prox switch but rotation is 1200
RPM and it might be too fast. Any better ideas??

Thanks in Advance!
oldpilot

 

[BobM3]

How about a tachometer with a low speed alarm? You could use your dowel pin/prox switch as the input to the tach. Actually, more than 1 pulse/revolution would be desirable for the tach. A gear with a prox. switch is often used. Almost anything that generates a pulse can be used with a tachometer.

 

[hydtools]

Look at a magnetic pickup speed switch to sense underspeed and activate an alarm.

http://www.govconsys.com/dynalco_products.htm

Ted

 

[limey1]

Q. Does the operator have a backup plan if, when the drive belts break? How is the batch to be saved in the event of a failure even with a warning in place?