energy consumption in a given situation 1

[maryden]

Simply put, if a nine ton payload needs to be hoisted a distance of between sixty and one hundred metres upwards how much energy would the crane used consume? And how many times would a crane motor (as found on a bridge crane type) be able to work with hoisting this weight four times an hour (fifteen minute cycle x 4) before it needs a service? I am new to this and would be grateful for some help, please.

 

[jraef]

Are you just trying to estimate the energy consumption or are you trying to size the motor? If it is energy consumption, you can assume all of the other important considerations in design are already done and use the formula

P = WV²/550*g*t

where P = Power in HP,
W = total weight (including drum, wire and load),
V = Velocity of the lift
g = acceleration of gravity and
t = duty cycle time.

If you are trying to properly size a motor for a hoist application, stop now and turn this over to someone who knows ALL of the very important safety considerations. The fact that you even have to ask immediately identifies you as unqualified to perform this vital safety related task. If you are being told to do it anyway, have your boss pre-write and sign the letters to the survivors of the future victims of a failed application when the hoist drops a load on someone.

"Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
— Kilgore Trout (via Kurt Vonnegut)
For the best use of Eng-Tips, please click here -> faq731-376

 

[electricpete]

Good points.

I'm not familiar with the work equation in that form, but I'll take jeff's word on it

.
Regarding energy consumptionA, of course in addition to work output, we a also consider motor losses, resistor losses, and mechanical losses.

Working on a tiny phone again excuse my typo's

=====================================
(2B)+(2B)' ?

 

[waross]

I get about 2 1/2 KWHrs per lift.
According to convert-to.com
1 foot pound (ft lb) = 0.00 037 661 609 706 watt hours (Wh)
I rounded up to 6,000,000 ft lbs. and rounded the final answer up another 10% to allow for the weight of rigging and mechanical losses.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[stevenal]

Might want to consider motor efficiency as well.

 

[waross]

Simply put, if a nine ton payload needs to be hoisted a distance of between sixty and one hundred metres

I based my estimate on the maximum 100 meters. More than enough to allow for efficiency when the shorter lifts are averaged in.

Bill
--------------------
"Why not the best?"
Jimmy Carter