Enter two of the three values into the calculator to compute the missing field using the 3 Phase Breaker formula (assumes a balanced three-phase system at unity power factor, PF = 1).
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3 Phase Breaker Formula
The following equation is used to calculate the total load, line voltage, or circuit current in a balanced three-phase electrical system at unity power factor (PF = 1).
TL = (√3 × V × CB) / 1000
- Where TL is the total load in kilowatts (kW) at PF = 1
- V is the line voltage in volts (V)
- CB is the circuit current in amperes (A) (often used to estimate breaker current)
If the power factor (PF) is not 1, use TL = (√3 × V × CB × PF) / 1000 and CB = (TL × 1000) / (√3 × V × PF). Actual breaker selection should follow applicable electrical code requirements (for example, continuous-load sizing and the next standard breaker rating).
What is a 3 Phase Breaker Calculator?
Definition:
A 3 Phase Breaker Calculator is a tool used to estimate a missing parameter in a three-phase electrical system, helping with load calculations and electrical safety planning.
How to Use the 3 Phase Breaker Calculator?
Example Problem:
The following example outlines the steps and information needed to calculate a missing field in a three-phase breaker system.
First, determine the known values. In this example, assume the total load is 20 kW (PF = 1) and the line voltage is 400 V.
Next, leave the Circuit Breaker Size field empty to let the calculator compute its value.
Finally, calculate the circuit breaker size using the formula above:
CB = (TL × 1000) / (√3 × V)
CB = (20 × 1000) / (√3 × 400)
CB ≈ 28.87 A
FAQ
What parameters are required for the 3 Phase Breaker Calculator?
The calculator requires two out of the three parameters: total load (kW, assuming PF = 1), line voltage (V), and circuit breaker size (A); the missing parameter is then computed automatically.
How do I choose which field to leave empty?
You should leave exactly one field empty so that the calculator can determine its value based on the other two provided inputs.
Can this calculator be applied to all three‐phase systems?
While it is designed for most standard balanced three‐phase systems, it assumes unity power factor (PF = 1) and does not replace electrical-code sizing requirements; variations in system configuration and load characteristics might require additional considerations, so consulting an electrical professional is recommended when in doubt.