Solving Delta Connected Load: Find Phase Current in PU and SI Units

In summary, we have a balanced 3 phase load operating at 90% nominal voltage and 100% line current. If the load is delta connected, the phase current in per unit and SI units can be calculated. The correct per unit line current value is 0.58 pu, but the given answer is 6.7A. The discrepancy may be due to the incorrect use of the formula for delta connected loads where I phase = I line/√3. This results in a factor of 1/√3 difference in the calculation. Additionally, the delta connection produces 1/3 of the instantaneous power compared to the same impedance and voltage.
  • #1
vvl92
13
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A balanced 3 phase load is rated at S=10KVA and 500V. The device is operating at 90% nominal voltage and 100 % line current.

The question is:
if the load is delta connected, find the phase current in per unit and SI units.

I calculated correctly that the per unit line current value is 0.58 pu, but the answer given for Ip=6.7A and I don't see why.

I calculated S=VI* S/V=I*=20A and 6.7 is 20/3...I thought that for delta connected load, you Iphase=Iline/√3... I am out by a factor of 1/√3 please explain!
 
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  • #2
Also can anyone explain why delta connection produces 1/3 of the instantaneous power given the same Z and V?
 

1. What is a delta connected load?

A delta connected load is a type of electrical connection where three loads are connected in the shape of a triangle. This type of connection is commonly used in three-phase systems.

2. How do you solve for phase current in a delta connected load?

To solve for phase current in a delta connected load, you can use the formula Iph = Iline/√3, where Iph is the phase current and Iline is the line current. This formula applies to both PU (per unit) and SI (International System of Units) units.

3. What are PU and SI units?

PU (per unit) units are a method of expressing the magnitudes of electrical quantities, such as voltage and current, in a relative or percentage form. SI (International System of Units) units are the standard units of measurement used in the scientific community, including electrical quantities such as volts, amps, and ohms.

4. Why do we need to convert between PU and SI units?

Converting between PU and SI units allows for easier comparison and analysis of electrical quantities, as well as simplifying calculations and equations. It also ensures consistency and accuracy in measurements across different systems and countries.

5. What are some common applications of solving for phase current in a delta connected load?

Solving for phase current in a delta connected load is useful in various industries, including power distribution, renewable energy systems, and industrial automation. It is also important in troubleshooting electrical issues and designing efficient electrical systems.

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