Electrical Load demand calculations

At first, you have to make clear what kind of load it is, so that we can have relevant coeficient to mulitiply.

Thanks for your reply. It has mixed type of loads, mainly single phase lights, fans, air conditioners, water storage geysers. One no. 3 HP 3 phase 440 volts pump motor. Please also advice me how to distribute loads so that I can gain maximum advantage with minimum installation and recurring cost.

you need to mention following data also to be able to do load calculation:

1) how many electric motors are there which you are using in your house, what are their types (3phase , 1 phase etc).

2)are you using starters in your house for above motors, are they likely to be started together ?

3) will these motors run all at the same time.

4)what is the total connected load of your house.

5) Is it likely that all the connected load will be switched on together.

6) also, considering Future expansion is very important, you can take 10 to 30% extra for future expansoion depending on expansion that is possible.

Thanks for your reply. Yes I ll use 1 no. 3 HP 3 phase 440 Volts motor for water pump, and may be single phase motors in air condition machine etc.

For these motors I ll use starters as recommended.

Total connected load is about 24 Kilowatts

I ll not use all the loads together normally, but may be (not sure) some time i ll use during any party at home. But please advice as per normal and regular uses.

At present there is no scope of any expansion of area of my house, so if it is necessary to consider expansion any time, I think 10% will be enough for me.

Thanks again, and waiting got your advice.

The maximum demand is depending on the loads you run at the same time. If you run all the loads at the same time you will have your 24KVA on your demand meter reading. Some of the utilities they make you sign an agreement for your demand. This demand agreement will have a minimum and maximum range usually +/-15%. So if you sign agreement for 20KVA, you will be okay to run between 17 to 23KVA (the range you have to check with your utility company). Let us assume in the winter your demand in a particular month is 10KVA, means still you have to pay your minimum agreed demand of 17KVA, If you demand in the summer may be is 24KVA, which is more than your maximum 23KVA, so you have to pay a penality (ratchet) price for 24KVA for the next 12 months no matter how low your KVA is for the next consecutive 11 months are.

My point is:

1 - when you sign agreement if it is possible try to sign for one year. But most of them they force you to sign for 5 years.

2- If you get for one year agreement sign for a high (may be 18KVA demand, you will get +/- 15% range)

3- Track your KVA demand in a year (from your bill) and determine what is the maximum KVA was in a year, so when you sign agreement in the next term that will be your maximum KVA.

4- some people they use 65% coincident demand factor (24 x .65) = 15.6KVA but it has some risk.

I hope this helps if you need further information, put it in this blog

In determining power requirements a "Load Analysis" must be prepared. Yes you can do it yourself if you know how with simple math. The idea behind it is the fact that if you totaled the connected load in your residedance or onsite power and used that for sizing your power source, you would need a transformer or generator somewhere near the size of your house! I deal with onsite power and sizeing a generator is a critical path! We have to know this information prior to buying generators/engines and it has to be right. Now back to your question: Power usage is calculated on a duty factor, e.g., how much load in kw and how many parts of a 24 hour period it is used. For example, suppose you have electric heating that is say, 10 kw. Your heating unit kicks on about 30% of the time in a 24 hour period. You then have a usage factor of 0.3 time 10 kw equal 3 kw. These usage factors imminated from recording equipment, documented and handed down in many industires. These factors are determined by application, however, some are the same for the example above. Common sense tells us that the example I used was based on a warmer climate that northern states/countries.