Resistance & Diameter of heating element

AI Thread Summary
The discussion centers on the discrepancies between theoretical and measured resistance values of a heating element designed for a 220V, 9KW power supply. The calculated resistance is 5.4 Ohms, while a multimeter shows 17 Ohms, prompting inquiries about the reasons for this difference. Participants explain that the heating element's connection configuration, either star (Y) or delta, affects resistance measurements, with delta connections requiring three times the resistance of Y connections. Additionally, the voltage supply in KSA is confirmed to be 220V per phase, with 380V between phases, which contrasts with the typical 208V three-phase supply in the US. The conversation highlights the complexities in calculating resistance and diameter of heating elements, emphasizing the need for accurate configurations and measurements.
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Design of heating element:

Supply Voltage: 220V/3Ph/60HZ, Power: 9KW

Resistance= VXV/P= 220X220/9000= 5.4 Ohms, But when physically when measure the resistance of wire using multimeter it is showing 17 ohms. Can you explain why there is differnece in practical and theortical value.

Also, to find the diameter divide the found resistance by length and select the dia close to having resisitivity(R/L= Ohm/Meter) of above formula. But same as with this caluculation there is large deviation in values.

or can anyone provide a link to the literature find the resistance & dia of heater element.

Thanks in advance for help
 
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How is the heating element connected to three phase power?

And more, we usually have 208V three phase in the US, don't we? Where does the 220V come from?
 
Phrak said:
How is the heating element connected to three phase power?

And more, we usually have 208V three phase in the US, don't we? Where does the 220V come from?


The elements are connected in star or Y connection.

here KSA 220V/3PH is available.
 
I see. Apparenly the voltage of each leg of the Y is 220 VAC. So from each leg to another leg is 380 VAC.

If your heating element is connected in delta configuration, each leg of the delta should have three times the resistance of a Y element.

380*380/9000 = 16 Ohms.
 

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