Foe Maxmium Demand Question No 3.

I was looking at the example on pg 360.

You have to put in 3 phase load and balance it ,the answer they looking for is the max current in the phase.
The trick is ensure try to balance the load as close as possiable,
I wiil attempt later,

let me know if you had worked out.
thanks.

I did try and balance it.

Determine the maximum demand of the heaviest loaded phase in a domesticv electrical instalation having the following load-

21 Lighting points 3 + 2 = 5A

28 10A single socket outlets
+
8 10A socket outlets = 10A + 5A = 15A

1 range(2 hotplates 6kW/230v =13.04A

6.8kW oven) 6800/230= 14.78A

1 air conditioner- (single phase 4.8kW) 4500/230 = 19.56 x 0.75= 14.67A

1 clothes dryer - ( single phase 4.8kW) see reg pg360 = 10.43A

1 washing machine - ( single phase self heating - 3.2kW) = 6.96A

1 3phase instantaneous water heater (5.3kW per phase) 5300/230 = 23 x 0.333= 7.67A per phase

1 3 phase motor rated at 7.5A per phase = 7.5A per phase



arrange into 3 phase

RED YELLOW BLUE

5A

10A 5A

13.04A 13.04A

14.78A


6.96A

10.43A

14.67A

7.67 7.67 7.67

7.5 7.5 7.5


Total


Red= 50.17 Yellow= 43.64 Blue= 44.62


Max demand red phase= 50.17A

I hope this is right,can some one check this please.

re balance red= 45.17 yellow = 48.64 blue = 44.62

total demand = yellow phase = 48.64A


is it right please any one

Hi Has any one done question No 3 on maximum demand.on peer work book

Re: Maximum demand, Please explain.

--------------------------------------------------------------------------------

re balance red= 45.17 yellow = 48.64 blue = 44.62

total demand = yellow phase = 48.64A


is it right please any one

Please reply.

I got 69.03A , 42.84A and 43.82A

Question 4 i got 272.76A , 224.88A and 203.31A. Not sure if these are right. Views and opinions please.

BTW the last calulation was worked out a while back. So it may be totally wrong.

Q4 is not right,I think,please see example on pg361.

Is this not total 72,9A?

If got
Ai)28p+16+2=46p= 7A
B)13p+18+1= 15A
C)30,2A+6,5A=36,7A
F) 14,2A
total: 72,9A

Nope. Have a look at mine and Askars

And what is with the clothes drier? U both don´t calculate anything for this one, but it has an demand of 6.5A. It doesn´t count as laundry equipment? confused

Dont take cloth dryer.check the explaination on the max demand notes.

Hm...i still have the same.

Clothesdryer = Group C) Ranges, cooking appliances, laundry equipment or socket-outlets rated at more than 10A for the connection thereof

3000W:240V=12,5A x0,5=6,25A

Can´t find a note which say something else!!!

Don´t know where i can edit my post, so double post.

Was at peer today, and u have to add the 6,25A from the clothes dryer to the max demand .