97catintenn
Senior Member
- Location
- Columbia, TN
What did 17kw have to do with it. The ranges are 13.2kw. So according to note one, you have to...WHAT?
Cooking Equipment
- Thread starter Flight987
- Start date
- Status
What did 17kw have to do with it. The ranges are 13.2kw. So according to note one, you have to...WHAT?
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
The OP has more than one question in this thread. The 17kW pertains to earlier problem.
97catintenn
Senior Member
- Location
- Columbia, TN
Part of the problem is figuring up the load on one phase and assume it's balanced for the equation. Then multiply your answer by 1.5 to get the total load on the three. To get the load on one phase, you have to take twice the max. load between any two phases per 220.54. Then goto Table 220.55 for the adjustment.
36 ranges with a 3 phase system, will come out to have 12 ranges between any two phases. so twice the max is going to be 24 ranges @ 13.6kw. Goto Table 220.55 Column C/ 24 ranges =39kw. But our range is over 12kw, it's 13.6 which rounds up to 14kw. So you must increase the 39kw by 10% which gives you 42.9kw.
42.9kw...but that's just on two legs of the three phase system. So, multiply by 1.5 to get the total for all three phases.
97catintenn
Senior Member
- Location
- Columbia, TN
Aww, sorry. That's what I get for just jumping in. i thought you were on a different calculation. And the OP said he didn't know what 17kw had to do it, so I thought we were all talking about the same problem.
I see that in220.55
I see that in220.55
I printed off your Inf.. I get the 12 ranges Between any two phases = 24 You round it up, because it is .6?
What if it was .3? Then we round down? Why do we round them off any way? What if the example was a
odd number, like 37 ranges.
No, I didn't make it to 42.9 kw.
Is your 10 percent the figured two major fraction's? Maybe I did get the 39kwx1.10=42.9
So if we rounded down then the major fraction would be 1.05?
Your turn.
I see that in220.55
I printed off your Inf.. I get the 12 ranges Between any two phases = 24 You round it up, because it is .6?
What if it was .3? Then we round down? Why do we round them off any way? What if the example was a
odd number, like 37 ranges.
No, I didn't make it to 42.9 kw.
Is your 10 percent the figured two major fraction's? Maybe I did get the 39kwx1.10=42.9
So if we rounded down then the major fraction would be 1.05?
Your turn.
Last edited:
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Okay you got this far, we have solved for 2 of the 3 phases, let's get the third.
We can divide by 2 and then multiply by 3, or more simply multiply our answer by 1.5.
42.9 x 1.5 = 64.35.
We can divide by 2 and then multiply by 3, or more simply multiply our answer by 1.5.
42.9 x 1.5 = 64.35.
97catintenn
Senior Member
- Location
- Columbia, TN
Glad to see you're back and asking questions. I'm working on these too. For the first question, you asked if I rounded up the .6? The .6 came from the kw rating of the range, not the total count. If you have 37 ranges and three phases, you are going to have more between two of the phases than the others, so you calculate the total using those numbers. 37 ranges. Phase AB=12ranges Phase BC=12ranges and Phase AC=13ranges.
So, you would work twice the max...max in this case is going to be 13ranges on phase AC. twice 13=26ranges for the calculation. There is no rounding for this part.
The rounding came in when you said the ranges were 13.6kw. Remember Note 1 says that for kw and major fraction thereof, you add 5%. For 13.6 you add 10% (the .6 is a major fraction).
So, back to figuring with 24 ranges @ 12kw comes to according to table 220.55...39kw. This has to be increased by the 10% we figured in the above line.
Then you have to figure the total power for all three phases
It's a long equation
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Glad to see you're back and asking questions. I'm working on these too. For the first question, you asked if I rounded up the .6? The .6 came from the kw rating of the range, not the total count. If you have 37 ranges and three phases, you are going to have more between two of the phases than the others, so you calculate the total using those numbers. 37 ranges. Phase AB=12ranges Phase BC=12ranges and Phase AC=13ranges.
So, you would work twice the max...max in this case is going to be 13ranges on phase AC. twice 13=26ranges for the calculation. There is no rounding for this part.
The rounding came in when you said the ranges were 13.6kw. Remember Note 1 says that for kw and major fraction thereof, you add 5%. For 13.6 you add 10% (the .6 is a major fraction).
So, back to figuring with 24 ranges @ 12kw comes to according to table 220.55...39kw. This has to be increased by the 10% we figured in the above line.
Then you have to figure the total power for all three phases
Alot of fun these problems,eh?
97catintenn
Senior Member
- Location
- Columbia, TN
Yeah. I've been working on motor calcs. Those seem to take too much time just to figure feeders, overcurrent protection, and short circuit protection...and then I turn the page and it goes to the calculation when you have several motors to calculate together.:happyno: I'm just hoping I score high enough with the other questions to skip the motor calcs.
- Status