Resistance & Diameter of heating element

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SUMMARY

The discussion focuses on the resistance and diameter calculations of a heating element designed for a 220V three-phase system with a power rating of 9KW. The theoretical resistance calculated using the formula \( R = \frac{V^2}{P} \) yields 5.4 Ohms, while a physical measurement using a multimeter shows 17 Ohms, indicating discrepancies due to factors such as wire length and temperature. The diameter of the heating element is determined by dividing the resistance by the length and selecting a diameter that corresponds to the resistivity. The heating element is connected in a star (Y) configuration, with each leg measuring 220 VAC, resulting in a line-to-line voltage of 380 VAC.

PREREQUISITES
  • Understanding of three-phase electrical systems
  • Knowledge of resistance and resistivity calculations
  • Familiarity with heating element design principles
  • Experience with multimeter usage for resistance measurement
NEXT STEPS
  • Research the impact of temperature on resistance in heating elements
  • Learn about the differences between star (Y) and delta configurations in three-phase systems
  • Explore the calculation of resistivity and its application in heating element design
  • Investigate the standards and variations in three-phase voltage systems across different regions
USEFUL FOR

Electrical engineers, heating element designers, and technicians involved in three-phase power systems and heating applications will benefit from this discussion.

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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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