Maximum demand, Please explain.
#31
Just Joined
Joined: Jun 2010
Posts: 25
Re: Maximum demand, Please explain.
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 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.
#32
Re: Maximum demand, Please explain.
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 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.
#33
Just Joined
Joined: Jun 2010
Posts: 25
Re: Maximum demand, Please explain.
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.
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.
#34
Just Joined
Joined: Jun 2010
Posts: 25
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
total demand = yellow phase = 48.64A
is it right please any one
#35
Just Joined
Joined: Jun 2010
Posts: 25
Re: Maximum demand, Please explain.
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.
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.
#36
Re: Maximum demand, Please explain.
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.
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.
#37
Re: Maximum demand, Please explain.
Question 4 i got 272.76A , 224.88A and 203.31A. Not sure if these are right. Views and opinions please.
#38
Re: Maximum demand, Please explain.
BTW the last calulation was worked out a while back. So it may be totally wrong.
#39
Just Joined
Joined: Jun 2010
Posts: 25
Re: Maximum demand, Please explain.
Q4 is not right,I think,please see example on pg361.
#40
Just Joined
Joined: Jul 2010
Posts: 13
Re: Maximum demand, Please explain.
Determine the maximum demand of a single phase 240V domestic installation.
28 Lighting points
+
8m Lighting track + 2 50W exhaust fans = 28+16+2= 46 points. Which is 3+2+2=7A
13 10A single socket outlets
+
9 10A double socket outlets + 1 1200 watts strip heaters = 13+9+1= 23 points so that would be 10+5=15A
2 50W exhaust fans
1 1200Watts strip heaters
1 14.5KW range 14500/240 = 60.41 x 0.5 = 30.2A
1 3.4kW storage H.W.S. 3400/240 = 14.16A
1 3.0kW clothes drier N/A
Total = 66.36A
This is what i get after revising the above. Just wondering where you get the extra 0.5A from?
28 Lighting points
+
8m Lighting track + 2 50W exhaust fans = 28+16+2= 46 points. Which is 3+2+2=7A
13 10A single socket outlets
+
9 10A double socket outlets + 1 1200 watts strip heaters = 13+9+1= 23 points so that would be 10+5=15A
2 50W exhaust fans
1 1200Watts strip heaters
1 14.5KW range 14500/240 = 60.41 x 0.5 = 30.2A
1 3.4kW storage H.W.S. 3400/240 = 14.16A
1 3.0kW clothes drier N/A
Total = 66.36A
This is what i get after revising the above. Just wondering where you get the extra 0.5A from?
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
#43
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Joined: Jun 2010
Posts: 25
Re: Maximum demand, Please explain.
Dont take cloth dryer.check the explaination on the max demand notes.
#44
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Joined: Jul 2010
Posts: 13
Re: Maximum demand, Please explain.
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!!!
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!!!
#45
Just Joined
Joined: Jul 2010
Posts: 13
Re: Maximum demand, Please explain.
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 .
Was at peer today, and u have to add the 6,25A from the clothes dryer to the max demand .