Plant Power Requirements 3

[jdemitrovic]

I have a conveyor system that I am installing. I only have available 30amps @ 480 VAC. How should I size an additional buck/boost transformer? If I add up all the motor FLA's I am at about 50 amps, however they may not all run at the same time. With all the motors running will I draw the theoritical 50 amps? What is a realistic number that I need to provide? I am trying to prevent costly upgrades and materials.

 

[sreid]

I think it would be unusual for all the motors to be drawing FLA all the time. FLA might happen for a worst case fully loaded belt. Also, the motors might be oversized by the conveyor manufacturer.

 

[controlsdude]

I refer you to NEC article 430.24 if continuous motor
if not continuous article 430.22(e)

I have been in mhe industry for >10 years, I have always rated the panel with multiple motors*1.25. I do not think you can not get away with a 60 amp feed. You stated above motors maybe on continously.

 

[gepman]

You need to follow the NEC as controlsdude says. I don't quite understand your question since a transformer will change your voltage put it doesn't increase the amount of power available.

I will say that I have seen the most absurdly sized motors on conveyors, both under and over sized. I guess it is due to the inability to either calculate the friction or allow for lack of maintenance.

 

[jdemitrovic]

gepman

Sorry for the confusion. I have 230 VAC available. The transformer gets me to the required 480 VAC. My current transformer is only a 30 kva transformer and I do not think this will be sufficient for this system. As far as the motor sizing I agree with you however in this case I believe the motors are sized appropiately. Thanks.

 

[BJC]

The real test of a conveyor system is when you have an unintentional shutdown. Many systems won't start a loaded belt system. You may need a stiff enough system to let you jog one belt at a time. Or lots of shovels and wheelbarrows.

 

[gepman]

You will need at least 45 kVA to get 50A but with starting motors you will probably want to upsize it. You do NOT want to overload dry type transformers for any period of time. Also if you have FVNR starters you need to check the size of the transformer versus the largest motor that will be started due to inrush of the motor. Don't start all of your conveyors at the same time.

 

[controlsdude]

yes you can usually get the programmer to start one motor at a time sequence. but trying to get away with not putting in the right size feed is not a way to start a conveyor project. been their done that

yes and customers always want to load up or overload product on conveyors.

worst I saw was pallet conveyor where they were always putting 2000# pallets on all the time. it had these air bag accumulation conveyor next to a tcar. the programming fixes I had to put just to make rate. makes my teeth grind remembering that experience.