Example Data Table
| Case |
VLL |
Mode |
Banks |
Branch Z |
Angle |
Expected Use |
| Temporary heater bank |
480 V |
Balanced |
1 |
12 Ω each |
30° |
Panel demand check |
| Parallel equipment set |
240 V |
Balanced |
2 |
8 Ω each |
0° |
Resistive site load |
| Mixed branch loading |
415 V |
Unbalanced |
1 |
10, 12, 15 Ω |
15°, 25°, 35° |
Uneven delta branch review |
Formula Used
Delta phase voltage: Vphase = VLL
Parallel branch impedance: Zeq = Zbranch ÷ N
Branch current: IAB = VAB ÷ ZAB(eq)
Line current: IA = IAB − ICA
Line current: IB = IBC − IAB
Line current: IC = ICA − IBC
Total complex power: Stotal = Σ(Vphase × Iphase*)
Balanced shortcut: Iline = √3 × Iphase
Design current: Idesign = Imax line × demand factor × safety factor
How to Use This Calculator
- Enter the line-to-line voltage for the construction panel.
- Select balanced mode when all delta branches match.
- Select unbalanced mode when branch impedances differ.
- Enter branch impedance values in ohms.
- Enter each impedance angle in degrees.
- Set the number of identical delta banks in parallel.
- Add demand and safety factors for planning current.
- Press Calculate to view results above the form.
- Use CSV or PDF buttons to export the same calculation.
Construction Delta Load Planning
A parallel delta load calculator helps plan three phase loads used on construction projects. It can support temporary panels, heaters, welders, pumps, compressors, and motor groups. A delta connection places each load branch across the line voltage. That means each branch sees full line to line voltage. This is different from a wye connection. In a balanced case, the line current is higher than the branch current by the square root of three. In an unbalanced case, phasor math gives a better result.
Why Parallel Delta Loads Matter
Many construction sites use repeated equipment banks. Several identical delta loads may be connected in parallel. Parallel branches reduce equivalent impedance. Lower impedance raises current. The calculator treats the entered branch impedance as one load bank. It then divides branch impedance by the number of identical banks. This gives an equivalent delta branch for the set. The tool also keeps phase angle in the calculation, so real power and reactive power remain visible.
Reading the Results
The result table shows branch current, line current, total apparent power, real power, reactive power, power factor, and load unbalance. These values help compare demand against panel capacity. The design current uses the largest line current. It then applies the demand factor and the safety factor. This gives a planning current for conductor and breaker review. It is not a final code approval.
Practical Use on Site
Use the calculator before adding temporary equipment. Start with the line voltage. Enter branch impedance values from nameplates, test data, or engineering notes. Use the balanced mode when all three branches match. Use the unbalanced mode when one branch differs. Set the number of parallel banks. Add a demand factor when the full connected load will not run at the same time. Add a safety factor for continuous duty or conservative planning. Export the CSV for spreadsheets. Export the PDF for a field record. Always compare results with electrical rules. Check manufacturer data, conductor ratings, and temperature limits. Get a professional review. This calculator supports construction estimating, but site conditions still control final decisions. Keep records with dates, assumptions, and equipment names, because later changes can shift feeder demand and planned protection sizes on site.
FAQs
What is a parallel delta load?
It is a delta connected three phase load where identical load banks are connected in parallel. Parallel banks lower equivalent impedance and raise current.
Why does the calculator use line-to-line voltage?
In a delta connection, each branch is connected directly across two lines. Therefore, branch voltage equals line-to-line voltage.
What does impedance angle mean?
Impedance angle shows how much current lags or leads voltage. Positive angles usually represent inductive loads. Negative angles usually represent capacitive loads.
When should I use unbalanced mode?
Use unbalanced mode when AB, BC, and CA branches have different impedance values or angles. It gives phasor-based line current results.
What is design current?
Design current is the largest calculated line current after demand and safety factors are applied. Use it for planning checks only.
Can this select a final breaker?
No. It suggests the next common amp size for review. Final breaker selection must follow code, conductor limits, equipment ratings, and duty type.
Why is current unbalance important?
High unbalance can overheat conductors, motors, and equipment. It may also show incorrect branch loading or faulty field data.
Can I export the calculation?
Yes. Use the CSV button for spreadsheets. Use the PDF button for a simple field report with summary values.