Re: Zero Speed Switch
Hello,
I think, generally there is one zero speed switch for conveyor or elevator. In case of conveyor, suppose the zero speed switch is at tail end. The conveyor will stop whether the belt snaps anywhere in carrying run or anywhere in return run, because there will not be tension in the belt and consequently drive pulley will not be able to move the belt.
Possibly, equipment can be provided with 2 zero speed switches (at 2 different items), so that even if one switch fails, the other switch will protect the equipment. The switches command will go parallel, and with the inbuilt functional logic that the stop command from any of the switch will stop the equipment. Such logic should also display the failure of the particular switch, for remedial measure.
Ishwar G. Mulani
Author of Book : Engineering Science And Application Design For Belt Conveyors (new print November, 2012)
Author of Book : Belt Feeder Design And Hopper Bin Silo
Advisor / Consultant for Bulk Material Handling System & Issues.
Pune, India.
Tel.: 0091 (0)20 25871916
Email: conveyor.ishwar.mulani@gmail.com
Website: www.conveyor.ishwarmulani.com ■
Zero Speed Switch
Dear Bulk-onliners,
I've found a recommendation about zero speed switches at CEMA book (6th Edition page 340). It says:
"A zero speed switch should be placed on every non- powered fixed major pulley in a conveyor system. Major pulleys would include terminal pulleys and bend pulleys."
It means that a belt conveyor with a counterweight and snub should have switches at tail, bending, and snub pulleys which is 4 switches (since there are two bend pulleys).
Is it really done in belt conveyor design? I have seen many conveyors designed by creditable companies, they just put one zero speed switch at tail drum.
Is there any other reference for it?
thanks
samad ■