Heater wiring in Star or Delta

Thread Starter

kallileo

Joined Dec 25, 2013
5
I have a 12kW heater which has 3x 4kW 230V elements.
I wire it into Star connection and apply ~3, 400V in order to have 230V phase voltage and the line current is around 18A.
1. How much will the power increase if the heater is wired in Delta at 400V (if it doesn't burn)?
2. What will be the line current if I wire it in Delta and apply ~3, 240V (I suppose the power will remain the same)?
 

inwo

Joined Nov 7, 2013
2,419
I have a 12kW heater which has 3x 4kW 230V elements.
I wire it into Star connection and apply ~3, 400V in order to have 230V phase voltage and the line current is around 18A.
1. How much will the power increase if the heater is wired in Delta at 400V (if it doesn't burn)?
2. What will be the line current if I wire it in Delta and apply ~3, 240V (I suppose the power will remain the same)?
If you almost double the voltage, elements will burn out.:eek:
Ohms law. Resistance stays the same,

Each element drawing 29 amps. 11.6 KW

Line current 50 amps. total of 35KW

Line current in delta is greater than element current by the square root of 3. ~1.732

Not considering increased resistance at incandescence.
 
Last edited:

Thread Starter

kallileo

Joined Dec 25, 2013
5
At the moment I wire it in Star and I get 18A line current and 12kW at 400V, which is normal.
If the voltage is lowered to 230v and I wire it in Delta shouldn't the line current remain the same since I lowered the voltage?
 

inwo

Joined Nov 7, 2013
2,419
I have a 12kW heater which has 3x 4kW 230V elements.
I wire it into Star connection and apply ~3, 400V in order to have 230V phase voltage and the line current is around 18A.
1. How much will the power increase if the heater is wired in Delta at 400V (if it doesn't burn)?
2. What will be the line current if I wire it in Delta and apply ~3, 240V (I suppose the power will remain the same)?
Which is it?:confused:

The current will follow the voltage across each element.

edit: amplitude
 
Last edited:

Thread Starter

kallileo

Joined Dec 25, 2013
5
If your going to end up with the same wattage and current, why change it?
I need it be installed on ~3, 230V and I need to calculate the line current to choose proper circuit breaker.
The resistance of every heating element is 13Ω.
According to the calculation I did the power remains the same but the line current will increase to 30A.

Delta:
I(phase) = 230V / 13Ω = 17,5A
I(line) = 1,73*I(phase) = 30A

I(line) = 30A
P=1,73*30*230 = 12kW

I believe that the calculations are correct.
 
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