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Fault Impedance is a measure of the resistance and reactance in an electrical circuit that is used to calculate the fault current that flows through the circuit in the event of a fault. Check FAQs
Zf=EaI1-(Z1+Z2)
Zf - Fault Impedance?Ea - A Phase EMF?I1 - Positive Sequence Current?Z1 - Positive Sequence Impedance?Z2 - Negative Sequence Impedance?

Fault Impedance using A-Phase EMF(LLF) Example

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With units
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Here is how the Fault Impedance using A-Phase EMF(LLF) equation looks like with Values.

Here is how the Fault Impedance using A-Phase EMF(LLF) equation looks like with Units.

Here is how the Fault Impedance using A-Phase EMF(LLF) equation looks like.

51.3427Edit=29.38Edit2.001Edit-(7.94Edit+-44.6Edit)
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Fault Impedance using A-Phase EMF(LLF) Solution

Follow our step by step solution on how to calculate Fault Impedance using A-Phase EMF(LLF)?

FIRST Step Consider the formula
Zf=EaI1-(Z1+Z2)
Next Step Substitute values of Variables
Zf=29.38V2.001A-(7.94Ω+-44.6Ω)
Next Step Prepare to Evaluate
Zf=29.382.001-(7.94+-44.6)
Next Step Evaluate
Zf=51.3426586706647Ω
LAST Step Rounding Answer
Zf=51.3427Ω

Fault Impedance using A-Phase EMF(LLF) Formula Elements

Variables
Fault Impedance
Fault Impedance is a measure of the resistance and reactance in an electrical circuit that is used to calculate the fault current that flows through the circuit in the event of a fault.
Symbol: Zf
Measurement: Electric ResistanceUnit: Ω
Note: Value should be greater than 0.
A Phase EMF
A phase EMF is defined as the electromagnetic force of the a-phase in open conductor fault.
Symbol: Ea
Measurement: Electric PotentialUnit: V
Note: Value can be positive or negative.
Positive Sequence Current
Positive Sequence Current consists of balanced three-phase voltage and current phasors which are exactly at 120 degrees apart rotating counterclockwise in ABC rotation.
Symbol: I1
Measurement: Electric CurrentUnit: A
Note: Value can be positive or negative.
Positive Sequence Impedance
Positive Sequence Impedance consists of balanced three-phase voltage and current phasors which are exactly at 120 degrees apart rotating counterclockwise in ABC rotation.
Symbol: Z1
Measurement: Electric ResistanceUnit: Ω
Note: Value should be greater than 0.
Negative Sequence Impedance
Negative Sequence Impedance consists of balanced three-phase impedance phasors which are exactly at 120 degrees apart rotating counterclockwise in ACB rotation.
Symbol: Z2
Measurement: Electric ResistanceUnit: Ω
Note: Value can be positive or negative.

Other Formulas to find Fault Impedance

​Go Fault Impedance using Positive Sequence Current (LLF)
Zf=V1-V2I1

Other formulas in Impedance category

​Go Positive Sequence Impedance using Positive Sequence Voltage and A-Phase EMF(LLF)
Z1=Ea-V1I1
​Go Positive Sequence Impedance using A-Phase EMF and Positive Sequence Current(LLF)
Z1=EaI1-(Zf+Z2)

How to Evaluate Fault Impedance using A-Phase EMF(LLF)?

Fault Impedance using A-Phase EMF(LLF) evaluator uses Fault Impedance = A Phase EMF/Positive Sequence Current-(Positive Sequence Impedance+Negative Sequence Impedance) to evaluate the Fault Impedance, The Fault Impedance using A-phase EMF(LLF) formula is defined as the resistance that is present in an electrical power system when a fault occurs. The fault impedance represents the opposition to the flow of fault current in the power system, and it is an important factor in determining the magnitude of the fault current. Fault Impedance is denoted by Zf symbol.

How to evaluate Fault Impedance using A-Phase EMF(LLF) using this online evaluator? To use this online evaluator for Fault Impedance using A-Phase EMF(LLF), enter A Phase EMF (Ea), Positive Sequence Current (I1), Positive Sequence Impedance (Z1) & Negative Sequence Impedance (Z2) and hit the calculate button.

FAQs on Fault Impedance using A-Phase EMF(LLF)

What is the formula to find Fault Impedance using A-Phase EMF(LLF)?
The formula of Fault Impedance using A-Phase EMF(LLF) is expressed as Fault Impedance = A Phase EMF/Positive Sequence Current-(Positive Sequence Impedance+Negative Sequence Impedance). Here is an example- -37.857341 = 29.38/2.001-(7.94+(-44.6)).
How to calculate Fault Impedance using A-Phase EMF(LLF)?
With A Phase EMF (Ea), Positive Sequence Current (I1), Positive Sequence Impedance (Z1) & Negative Sequence Impedance (Z2) we can find Fault Impedance using A-Phase EMF(LLF) using the formula - Fault Impedance = A Phase EMF/Positive Sequence Current-(Positive Sequence Impedance+Negative Sequence Impedance).
What are the other ways to Calculate Fault Impedance?
Here are the different ways to Calculate Fault Impedance-
  • Fault Impedance=(Positive Sequence Voltage-Negative Sequence Voltage)/Positive Sequence CurrentOpenImg
Can the Fault Impedance using A-Phase EMF(LLF) be negative?
No, the Fault Impedance using A-Phase EMF(LLF), measured in Electric Resistance cannot be negative.
Which unit is used to measure Fault Impedance using A-Phase EMF(LLF)?
Fault Impedance using A-Phase EMF(LLF) is usually measured using the Ohm[Ω] for Electric Resistance. Megohm[Ω], Microhm[Ω], Volt per Ampere[Ω] are the few other units in which Fault Impedance using A-Phase EMF(LLF) can be measured.
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