1. What is Capacitor Inrush Current?

The inrush current is the instantaneous high current that flows when a capacitor is initially connected to a power source. This occurs because the uncharged capacitor initially acts as a short circuit.

2. How Does the Calculator Work?

The calculator uses the inrush current formula:

Where:

• \( I_{peak} \) — Peak inrush current (amps)
• \( V \) — Applied voltage (volts)
• \( ESR \) — Equivalent series resistance (ohms)

Explanation: The equation calculates the maximum current that flows when a capacitor is first energized, based on the voltage and the capacitor's internal resistance.

3. Importance of Inrush Current Calculation

Details: Understanding inrush current is critical for circuit design as excessive inrush current can damage components, trip circuit breakers, or cause voltage dips in the power supply.

4. Using the Calculator

Tips: Enter the applied voltage in volts and the capacitor's equivalent series resistance in ohms. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: Why is inrush current higher than steady-state current?
A: Because initially the capacitor acts as a short circuit (no charge), allowing maximum current flow limited only by ESR.

Q2: How can I reduce inrush current?
A: Common methods include using current-limiting resistors, NTC thermistors, or soft-start circuits.

Q3: Does capacitor size affect inrush current?
A: While capacitance doesn't appear in the basic formula, larger capacitors typically have lower ESR, which can lead to higher inrush currents.

Q4: Is inrush current dangerous?
A: It can be, as it may exceed component ratings or cause arcing in switches and contacts.

Q5: How does temperature affect inrush current?
A: ESR typically increases with lower temperatures, which would reduce inrush current slightly.