How Do You Calculate Voltage Drop in a Transformer?

In summary, Dyn Transformer voltage drop is the reduction in voltage that occurs when electricity flows through a transformer due to the resistance of its internal components. It is important to properly calculate and account for voltage drop in transformer design and installation to ensure efficient and safe performance of electrical systems. Ohm's Law can be used to calculate voltage drop, taking into account factors such as current, resistance, wire size, length, and load power factor. Excessive voltage drop can result in decreased efficiency, increased energy costs, and potential damage to equipment. To reduce voltage drop, larger wire size, shorter wire length, and minimizing load power factor can be utilized, as well as selecting a transformer with lower internal resistance and conducting regular maintenance and inspections.
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Homework Statement



A 3MVA 11kV/415V 3 Phase Transformer has the following parameters
+ve sequence resistance = 0.00355pu
+ve sequence reactance = 0.0901pu

Primary PHASE current to the transformer is 55A and the load power factor on secondary is 0.85 lagging. Calculate voltage Drop

The attempt at a solution

R = 0.00355pu = 0.355%
X = 0.0901pu = 9.01%

Secondary current (star so line and phase current will be same) = 55 * 11000/415 = 1457.83A

R(ohms) = (10*%R*kVsecondary2)/Txfr kVA = (10*0.3555*0.4152)/3000 = 0.0002038Ω

X(ohms) = (10*%X*kVsecondary2)/kVA = (10*9.01*0.4152)/3000 = 0.0051725Ω

Φ = cos^-1(0.85) = 31.788°

Volt Drop = Sqrt(3) * 1457.83 * (0.0002038*0.85 + 0.0051725*sin(31.788)) = 7.32V

Does this mean that the voltage to the load will be 415-7.32 = 407.68V?? This is the bit I would like confirming if the remainder of the calculations happen to be correct?

Thank you :)
 
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  • #2


Hi there,

Thank you for sharing your solution for this problem. Your calculations seem to be correct and the voltage drop you have calculated is the voltage drop across the transformer. This means that the voltage at the load will be 407.68V, as you have correctly stated. It is important to consider voltage drop when designing electrical systems to ensure that the voltage at the load is within acceptable limits.

If you have any further questions or concerns, please feel free to ask. Keep up the good work!
 

Related to How Do You Calculate Voltage Drop in a Transformer?

1. What is Dyn Transformer voltage drop?

Dyn Transformer voltage drop is the reduction in voltage that occurs when electricity flows through a transformer. This is due to the resistance of the transformer's windings and other internal components, which causes a drop in voltage as the electricity passes through.

2. Why is Dyn Transformer voltage drop important?

Dyn Transformer voltage drop is important because it affects the performance and efficiency of electrical systems. Excessive voltage drop can result in reduced power quality, equipment damage, and increased energy costs. Therefore, it is crucial to properly calculate and account for voltage drop in transformer design and installation.

3. How is Dyn Transformer voltage drop calculated?

Dyn Transformer voltage drop can be calculated using Ohm's Law, which states that voltage drop (V) is equal to the product of current (I) and resistance (R). In simpler terms, voltage drop is directly proportional to the amount of current flowing through the transformer and the resistance of its internal components. Other factors such as wire size, length, and load power factor also play a role in voltage drop calculation.

4. What are the effects of excessive Dyn Transformer voltage drop?

Excessive Dyn Transformer voltage drop can result in decreased system efficiency and increased energy costs. It can also cause voltage fluctuations, which can damage sensitive electronic equipment. In extreme cases, it can lead to overheating and failure of the transformer itself.

5. How can Dyn Transformer voltage drop be reduced?

Dyn Transformer voltage drop can be reduced by using larger wire size, shorter wire length, and minimizing the load power factor. Properly sizing the transformer for the load and selecting a transformer with lower internal resistance can also help reduce voltage drop. Regular maintenance and inspection of the transformer can also prevent excessive voltage drop due to wear and tear.

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