Bolted Fault Current Calculator

Bolted Fault Current Equation:

\[ I_{sc} = \frac{V}{Z} \]

Bolted Fault Current (I_sc):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Bolted Fault Current?

Bolted fault current is the maximum current that would flow in a circuit during a short circuit condition where all phases are connected together with zero impedance. It represents the worst-case scenario for electrical fault conditions.

2. How Does the Calculator Work?

The calculator uses the bolted fault current equation:

\[ I_{sc} = \frac{V}{Z} \]

Where:

\( I_{sc} \) — Bolted fault current (A)
\( V \) — System voltage (V)
\( Z \) — Total impedance (ohms)

Explanation: The equation calculates the maximum possible short-circuit current by dividing the system voltage by the total impedance in the fault path.

3. Importance of Bolted Fault Current Calculation

Details: Accurate bolted fault current calculation is essential for proper protective device coordination, equipment rating selection, and ensuring electrical system safety and reliability.

4. Using the Calculator

Tips: Enter system voltage in volts and total impedance in ohms. Both values must be positive numbers greater than zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between bolted fault and arcing fault?
A: Bolted fault assumes zero impedance connection, while arcing fault includes the impedance of the arc, resulting in lower current values.

Q2: Why is bolted fault current important for equipment selection?
A: Electrical equipment must be rated to withstand the maximum possible fault current to prevent catastrophic failure during short circuit conditions.

Q3: How does impedance affect fault current?
A: Higher impedance results in lower fault current, while lower impedance leads to higher fault current values.

Q4: What factors contribute to system impedance?
A: System impedance includes transformer impedance, cable impedance, busway impedance, and any other components in the fault path.

Q5: When should bolted fault current calculations be performed?
A: Calculations should be performed during system design, after any system modifications, and as part of regular electrical system maintenance and analysis.