Rectifier Ripple Factor
r = √((Vrms/Vdc)² − 1)
Quick answer
This calculator solves r = √((Vrms / Vdc)² − 1) for Ripple Factor. With Output RMS Voltage 120 V, Output DC Voltage 56.4 V, the result is 1.878. It solves in 3 directions, so you can enter the values you have and get the one you need.
Calculator
Formula
Description
The ripple factor measures how much residual AC remains on a rectified, filtered DC output, defined as the ratio of the RMS ripple to the DC value. It is the standard figure of merit for a power-supply filter: a smaller ripple factor means cleaner DC. An unfiltered half-wave output has r ≈ 1.21 and full-wave ≈ 0.48; a reservoir capacitor brings it down to a few percent.
Variables
- r — Ripple factor (fraction)
- Vrms — Total RMS of the output (DC + ripple) (V)
- Vdc — DC (average) component (V)
Practical Notes
Multiply by 100 for a percentage. Adding a filter capacitor or an LC/π filter reduces r dramatically; linear regulators then reject the rest.
Symbols and units
| Symbol | Meaning | Default unit | Accepted units |
|---|---|---|---|
| r | Ripple Factor | — | — |
| Vrms | Output RMS Voltage | V | pV, nV, µV, mV, V, kV |
| Vdc | Output DC Voltage | V | pV, nV, µV, mV, V, kV |
Step by step
- 1. What you know: Output RMS Voltage 120 V, Output DC Voltage 56.4 V
- 2. The relation: r = √((Vrms / Vdc)² − 1)
- 3. Substitute: Vrms = 120 V, Vdc = 56.4 V
- 4. Result: Ripple Factor = 1.878
Worked examples
Minimum range
Given: Output RMS Voltage 3.3 V, Output DC Voltage 1.55 V
Result: Ripple Factor = 1.88
Low range
Given: Output RMS Voltage 33 V, Output DC Voltage 15.5 V
Result: Ripple Factor = 1.88
Typical
Given: Output RMS Voltage 120 V, Output DC Voltage 56.4 V
Result: Ripple Factor = 1.878
High range
Given: Output RMS Voltage 2.3 kV, Output DC Voltage 1.08 kV
Result: Ripple Factor = 1.88
Maximum range
Given: Output RMS Voltage 23 kV, Output DC Voltage 10.8 kV
Result: Ripple Factor = 1.88
Solving for each variable
Solve for Ripple Factor
Output RMS Voltage 3.3 V, Output DC Voltage 1.55 V → 1.88
Solve for Output RMS Voltage
Ripple Factor 0.025, Output DC Voltage 0.726 V → 0.7262 V
Solve for Output DC Voltage
Ripple Factor 0.025, Output RMS Voltage 0.33 V → 0.3299 V
How Ripple Factor changes with Output RMS Voltage
| Output RMS Voltage (input) | Ripple Factor (result) |
|---|---|
| 0.48 kV | 1.518 |
| 0.84 kV | 3.021 |
| 1.2 kV | 4.434 |
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<p><a href="https://vbatpower.com/formulas/ripple-factor/">Rectifier Ripple Factor</a> Calculator by vbatpower.com</p>Frequently asked questions
How do you calculate Rectifier Ripple Factor?
Use r = √((Vrms / Vdc)² − 1). With Output RMS Voltage 120 V, Output DC Voltage 56.4 V, Ripple Factor works out to 1.878.
What is the formula for Rectifier Ripple Factor?
The formula is r = √((Vrms / Vdc)² − 1). The ripple factor measures how much residual AC remains on a rectified, filtered DC output, defined as the ratio of the RMS ripple to the DC value.
How do you find Output RMS Voltage when you know the other values?
Rearrange for Output RMS Voltage: with Ripple Factor 0.025, Output DC Voltage 0.726 V, Output RMS Voltage is 0.7262 V.
How do you find Output DC Voltage when you know the other values?
Rearrange for Output DC Voltage: with Ripple Factor 0.025, Output RMS Voltage 0.33 V, Output DC Voltage is 0.3299 V.
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