Fault Current(LLF) Calculator

✖A phase EMF is defined as the electromagnetic force of the a-phase in open conductor fault.ⓘ A Phase EMF [E_a]			+10% -10%
✖Positive Sequence Impedance consists of balanced three-phase voltage and current phasors which are exactly at 120 degrees apart rotating counterclockwise in ABC rotation.ⓘ Positive Sequence Impedance [Z₁]			+10% -10%
✖Negative Sequence Impedance consists of balanced three-phase impedance phasors which are exactly at 120 degrees apart rotating counterclockwise in ACB rotation.ⓘ Negative Sequence Impedance [Z₂]			+10% -10%

✖The fault current is the electrical current which flows through a circuit during an electrical fault condition.ⓘ Fault Current(LLF) [I_f]

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Formula

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Fault Current(LLF)

Formula

`"I"_{"f"} = (sqrt(3)*"E"_{"a"})/("Z"_{"1"}+"Z"_{"2"})`

Example

`"-1.388097A"=(sqrt(3)*"29.38V")/("7.94Ω"+"-44.6Ω")`

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Fault Current(LLF) Solution

STEP 0: Pre-Calculation Summary

Formula Used

Fault Current = (sqrt(3)*A Phase EMF)/(Positive Sequence Impedance+Negative Sequence Impedance)
I_f = (sqrt(3)*E_a)/(Z₁+Z₂)
This formula uses 1 Functions, 4 Variables

Functions Used

sqrt - A square root function is a function that takes a non-negative number as an input and returns the square root of the given input number., sqrt(Number)

Variables Used

Fault Current - (Measured in Ampere) - The fault current is the electrical current which flows through a circuit during an electrical fault condition.
A Phase EMF - (Measured in Volt) - A phase EMF is defined as the electromagnetic force of the a-phase in open conductor fault.
Positive Sequence Impedance - (Measured in Ohm) - Positive Sequence Impedance consists of balanced three-phase voltage and current phasors which are exactly at 120 degrees apart rotating counterclockwise in ABC rotation.
Negative Sequence Impedance - (Measured in Ohm) - Negative Sequence Impedance consists of balanced three-phase impedance phasors which are exactly at 120 degrees apart rotating counterclockwise in ACB rotation.

STEP 1: Convert Input(s) to Base Unit

A Phase EMF: 29.38 Volt --> 29.38 Volt No Conversion Required
Positive Sequence Impedance: 7.94 Ohm --> 7.94 Ohm No Conversion Required
Negative Sequence Impedance: -44.6 Ohm --> -44.6 Ohm No Conversion Required

STEP 2: Evaluate Formula

Substituting Input Values in Formula

I_f = (sqrt(3)*E_a)/(Z₁+Z₂) --> (sqrt(3)*29.38)/(7.94+(-44.6))

Evaluating ... ...

I_f = -1.38809745571123

STEP 3: Convert Result to Output's Unit

-1.38809745571123 Ampere --> No Conversion Required

FINAL ANSWER

-1.38809745571123 ≈ -1.388097 Ampere <-- Fault Current

(Calculation completed in 00.004 seconds)

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Home » Engineering » Electrical » Power System » Fault » Shunt Faults » Unsymmetrical Faults » L-L Fault » Current » Fault Current(LLF)

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Created by Nisarg

Indian Institute of Technology,Roorlee (IITR), Roorkee

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Chandigarh University (CU), Punjab

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< 10+ Current Calculators

Positive Sequence Current using A-Phase EMF(LLF)

Go Positive Sequence Current = A Phase EMF/(Positive Sequence Impedance+Negative Sequence Impedance+Fault Impedance)

B-Phase Current using A-Phase EMF(LLF)

Go B Phase Current = (sqrt(3)*A Phase EMF)/(Positive Sequence Impedance+Negative Sequence Impedance)

Fault Current(LLF)

Go Fault Current = (sqrt(3)*A Phase EMF)/(Positive Sequence Impedance+Negative Sequence Impedance)

Positive Sequence Current using Fault Impedance(LLF)

Go Positive Sequence Current = (Positive Sequence Voltage-Negative Sequence Voltage)/Fault Impedance

B-Phase Current using Fault Impedance (LLF)

Go B Phase Current = (B Phase Voltage-C Phase Voltage)/Fault Impedance

C-Phase Current using Fault Impedance (LLF)

Go C Phase Current = (C Phase Voltage-B Phase Voltage)/Fault Impedance

Positive Sequence Current (LLF)

Go Positive Sequence Current = (-1)*Negative Sequence Current

Negative Sequence Current(LLF)

Go Negative Sequence Current = (-1)*Positive Sequence Current

B-Phase Current (LLF)

Go B Phase Current = (-1)*C Phase Current

C-Phase Current(LLF)

Go C Phase Current = (-1)*B Phase Current

Fault Current(LLF) Formula

Fault Current = (sqrt(3)*A Phase EMF)/(Positive Sequence Impedance+Negative Sequence Impedance)
I_f = (sqrt(3)*E_a)/(Z₁+Z₂)

What is a line to line fault?

A line-to-line fault, also known as a three-phase fault, is a type of electrical fault that occurs in a three-phase power system. This type of fault occurs when a failure occurs between two phases of the power system, causing a current to flow from one phase to the other.

How to Calculate Fault Current(LLF)?

Fault Current(LLF) calculator uses Fault Current = (sqrt(3)*A Phase EMF)/(Positive Sequence Impedance+Negative Sequence Impedance) to calculate the Fault Current, The Fault Current(LLF) formula is defined as the high level of electrical current that flows in a power system when a fault occurs. Fault Current is denoted by I_f symbol.

How to calculate Fault Current(LLF) using this online calculator? To use this online calculator for Fault Current(LLF), enter A Phase EMF (E_a), Positive Sequence Impedance (Z₁) & Negative Sequence Impedance (Z₂) and hit the calculate button. Here is how the Fault Current(LLF) calculation can be explained with given input values -> 0.968551 = (sqrt(3)*29.38)/(7.94+(-44.6)).

FAQ

What is Fault Current(LLF)?

The Fault Current(LLF) formula is defined as the high level of electrical current that flows in a power system when a fault occurs and is represented as I_f = (sqrt(3)*E_a)/(Z₁+Z₂) or Fault Current = (sqrt(3)*A Phase EMF)/(Positive Sequence Impedance+Negative Sequence Impedance). A phase EMF is defined as the electromagnetic force of the a-phase in open conductor fault, Positive Sequence Impedance consists of balanced three-phase voltage and current phasors which are exactly at 120 degrees apart rotating counterclockwise in ABC rotation & Negative Sequence Impedance consists of balanced three-phase impedance phasors which are exactly at 120 degrees apart rotating counterclockwise in ACB rotation.

How to calculate Fault Current(LLF)?

The Fault Current(LLF) formula is defined as the high level of electrical current that flows in a power system when a fault occurs is calculated using Fault Current = (sqrt(3)*A Phase EMF)/(Positive Sequence Impedance+Negative Sequence Impedance). To calculate Fault Current(LLF), you need A Phase EMF (E_a), Positive Sequence Impedance (Z₁) & Negative Sequence Impedance (Z₂). With our tool, you need to enter the respective value for A Phase EMF, Positive Sequence Impedance & Negative Sequence Impedance and hit the calculate button. You can also select the units (if any) for Input(s) and the Output as well.

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