Load Flow Planning Chart

Use this worksheet after the calculator result to record source voltage, source impedance, radial model boundary, load kW, PF, cable impedance, current, voltage drop, voltage regulation, losses, efficiency, and next-modeling notes.

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Quick reference table

A load flow planning chart is a calculator-led worksheet for a simplified distribution screen. It documents source impedance, radial model boundary, load power, load power factor, cable impedance, voltage regulation, losses, equipment voltage limits, adopted NEC checks, IEEE practice context, utility source data, and AHJ or facility requirements before a formal model or field validation.

Load flow planning worksheet

Load flow planning worksheet
Checkpoint	Record from calculator	Review before next model
Model boundary	Simple radial, voltage regulation, loss, or distribution mode	Confirm the calculator model matches the question
Source	Source voltage and source impedance	Confirm utility, transformer, or generator basis
Load	Load kW and PF	Confirm demand, diversity, and phase balance
Cable path	Length, resistance, reactance	Confirm route and conductor data
Voltage result	Load voltage, drop, regulation	Compare with equipment tolerance and voltage-drop target
Loss result	Resistive losses, reactive losses, efficiency	Review heat, energy, and conductor alternatives

Simplified model limits

Simplified model limits
Condition	Record on worksheet	Why it may need deeper modeling
Multiple sources	Utility, generator, tie, or parallel source notes	A single radial source cannot represent all operating states
Unbalanced load	Phase currents and single-phase load notes	Balanced three-phase math can hide neutral and phase-voltage issues
Motor starting	Starting current and voltage dip case	Running load flow can miss acceleration voltage behavior
Transformer taps or regulators	Tap position and control mode	Regulating equipment changes voltage profile
Harmonics or nonlinear loads	THD, VFD, UPS, rectifier notes	RMS current, heating, and voltage distortion may change results

Formula basis

Load current = kW x 1000 / (sqrt(3) x voltage x PF) for balanced three-phase. Voltage drop screen = multiplier x current x impedance.

Load current is calculated from load power, voltage, power factor, and system type.
Source impedance and cable impedance define the simplified model boundary used by the calculator.
Voltage regulation compares source and load voltage under the selected load condition.
Losses estimate the resistive and reactive loss values used for planning review.

Worked examples

Radial feeder planning recordRecord source voltage, source impedance, load kW, PF, cable length, cable R and X, load current, voltage drop, load voltage, and losses before changing conductor size.

Generator-backed distribution screenWhen the source may be a generator, keep generator voltage, source impedance, motor-starting load, voltage regulation, and load-sequencing notes beside the calculator result.

Assumptions. Balanced load and line-to-line voltage assumptions behind this chart.

The worksheet uses a simplified calculator model and does not replace coordinated short-circuit, voltage regulation, protection, or network load-flow review.
Unbalanced systems, multiple sources, motor starting, transformer taps, harmonics, and dynamic loads need deeper modeling or measurement.
Changing conductors or equipment from this screen still requires ampacity, protection, equipment terminal, available fault current, and project-load checks.

Code and standard notes. Planning limits that should be checked before final equipment selection.

Use this chart as a planning worksheet; verify adopted NEC requirements, IEEE power system practices, utility source data, equipment voltage limits, manufacturer data, available fault current, and AHJ or facility requirements before design changes.

How to use this chart

1Start with the model boundaryRecord whether the calculator result is simple radial, voltage regulation, loss analysis, load distribution, or complete-analysis mode.

2Preserve impedance inputsCopy source impedance, cable resistance, cable reactance, and cable length because they control voltage and loss results.

3Mark modeling gapsUse the worksheet to list unbalanced phases, multiple sources, motor starting, harmonics, load diversity, or regulator items that need deeper review.

Worksheet checklist. Record source basis, review gaps, and assumptions before using the chart result.

Capture source and loadDocument source voltage, source impedance, load kW, load power factor, system type, and operating source condition.
Capture feeder dataRecord cable length, resistance, reactance, total impedance, load current, voltage drop, load voltage, and loss result.
Capture planning decisionList whether the result points to conductor change, voltage support, load balancing, generator review, equipment tolerance review, or formal modeling.

Common mistakes to avoid. Review these before turning chart current into an equipment decision.

Treating a simplified radial result as a full network load-flow analysis for multiple sources or dynamic loads.
Changing conductor size from voltage drop alone without checking ampacity, protection, equipment terminals, and project load assumptions.
Ignoring source impedance, transformer taps, motor starting, or unbalanced phase loading when those conditions are the real cause of the voltage issue.

Frequently asked questions

These answers explain how to use the chart without turning a quick reference into a final design decision.

Can this chart replace a load-flow model?

No. It documents the simplified calculator result so a fuller model, equipment review, or field measurement can be scoped.

Why record cable reactance as well as resistance?

Reactance affects voltage drop and regulation in AC systems, especially on longer feeders or lower power factor loads.