Calculate electrical load, current or voltage from any two inputs with basic, single-phase AC or three-phase power factor options and units.
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Voltage from Load Formula
The following basic formula applies to DC or a single-phase unity-power-factor load. For single-phase AC, use V = P / (I × PF). For balanced three-phase AC, use VLL = P / (√3 × Iline × PF), or VLN = P / (3 × Iline × PF).
Variables:
- Where V is the Voltage from Load (volts)
- EL is the electrical load (watts)
- I is the circuit current (amps); the three-phase modes use line current
For the basic DC relation, divide real electrical load by circuit current. AC calculations also require power factor and the selected phase/voltage basis.
| Electrical Load (W) | Total Current (A) | Voltage (V) |
|---|---|---|
| 3.3 | 1 | 3.3 |
| 5 | 1 | 5 |
| 10 | 2 | 5 |
| 9 | 1 | 9 |
| 12 | 1 | 12 |
| 24 | 2 | 12 |
| 60 | 5 | 12 |
| 45 | 3 | 15 |
| 19 | 1 | 19 |
| 38 | 2 | 19 |
| 24 | 1 | 24 |
| 48 | 1 | 48 |
| 96 | 2 | 48 |
| 60 | 0.5 | 120 |
| 120 | 1 | 120 |
| 230 | 1 | 230 |
| 240 | 1 | 240 |
| 277 | 1 | 277 |
| 4000 | 10 | 400 |
| 4800 | 10 | 480 |
| Basic DC or single-phase unity-power-factor table. Uses V = P / I with base units: watts (W), amperes (A), volts (V). For reference: 1 kW = 1000 W, 1 kA = 1000 A, 1 mA = 0.001 A. | ||
How to Calculate Voltage from Load?
The following two example problems outline how to calculate the Voltage from Load.
Example Problem #1:
- First, determine the electrical load (watts). In this example, the electrical load (watts) is measured to be 7.
- Next, determine the total current (amps). For this problem, the total current (amps) is calculated to be 6.
- Finally, calculate the Voltage from Load using the formula above:
V = EL / I
Inserting the values from above and solving the equation with the imputed values gives:
V = 7 / 6 = approximately 1.1667 (volts)
Example Problem #2:
Using the same process as example problem 1, we first define the variables outlined by the formula. In this case, the values are:
electrical load (watts) = 4
total current (amps) = 10
Entering these values into the formula or calculator above gives us
V = 4 / 10 = .40 (volts)
