Engineering tools
Calculate a planning estimate, compare a scenario and send the inputs to an engineer. Choose from 26 tools for electrical systems and equipment.
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Move from estimate to verified design
Send the calculator result with your load schedule, single line diagram or site details. Our team will verify the assumptions and prepare a project quotation.
Worked examples
These examples use the default inputs. Change the live controls above for your own scenario; the reference examples below remain fixed.
Three-phase voltage unbalance — worked example
Example inputs
- L1–L2 voltage: 415 V
- L2–L3 voltage: 410 V
- L3–L1 voltage: 420 V
Example result
- Average line voltage: 415 V
- Maximum deviation: 5 V
- Voltage unbalance: 1.2 %
Assumptions & limits
- Unbalance (%) = 100 × maximum absolute deviation from the average / average.
- Use line-to-line readings taken under the same operating condition.
- No pass/fail limit or trip delay is selected. Check equipment limits and investigate supply conditions with a qualified engineer.
- This method uses voltage magnitudes only; it is not an IEC negative-sequence calculation.
- Preliminary planning only. Final selection needs project-specific engineering verification.
Method reference: US DOE — Energy Management for Motor-Driven Systems
DC control power budget — worked example
Example inputs
- DC output voltage: 24 V DC
- PLC and other continuous load: 25 W
- Simultaneously held DC coils: 6
- Holding power per DC coil: 3 W
- Simultaneous sensors: 10
- Power per sensor: 0.5 W
- Reserve allowance: 25 %
Example result
- Connected continuous load: 48 W
- Budget with reserve: 60 W
- DC output current budget: 2.5 A
Assumptions & limits
- Pload = PLC / other W + coil count × holding W + sensor count × sensor W.
- Pbudget = Pload × (1 + reserve / 100); Ibudget = Pbudget / DC voltage.
- Reserve is a planning assumption, not a manufacturer requirement.
- All listed loads must match the selected DC voltage. AC coil VA and DC coil watts are not interchangeable.
- Check coil pull-in peaks, simultaneous starting, temperature and altitude derating, overload behaviour and branch protection separately. This tool does not select a supply model.
- Preliminary planning only. Final selection needs project-specific engineering verification.
Method reference: MEAN WELL — Power supply selection FAQ
Managed EV charging capacity — worked example
Example inputs
- Connected charge points: 8
- Maximum power per charge point: 7.4 kW
- Site active-power limit: 100 kW
- Other simultaneous site demand: 60 kW
- Configured EV power cap: 30 kW
Example result
- Connected charging power: 59.2 kW
- Site headroom: 40 kW
- Managed EV allocation: 30 kW
Assumptions & limits
- EV allocation = min(connected power, max(0, site limit − other demand), configured EV cap).
- All limits are active power in kW, not kVA. The equal-share illustration assumes every connected point requests power.
- This is a snapshot: building demand and vehicle acceptance change over time.
- Verify phase loading, minimum charging current, metering, controller communications and fail-safe behaviour. A low allocation may require queued or paused sessions; it does not guarantee every vehicle can charge.
- This does not size cables, protection, service capacity or certify charger compatibility.
- Preliminary planning only. Final selection needs project-specific engineering verification.
Method reference: Schneider Electric — EV charging management systems
Methods and individual tools
Cable sizingCompare a protective-device rating with corrected cable capacity for the installation method you enter.Voltage dropEstimate feeder voltage drop from resistance, reactance and power factor, using your chosen voltage-drop limit.MCB / MCCB / ACB sizingFind a nominal current candidate using your design load, cable capacity and manufacturer correction factor.kVA ↔ ampsConvert apparent power and current, with active and reactive components at the power factor you enter.Motor starting currentEstimate motor current and explore a starting-current multiplier. Use nameplate and manufacturer data for the actual motor.Capacitor bank sizingEstimate required reactive-power correction and ideal capacitance for the connection you select.Short-circuit currentEstimate the initial symmetrical fault current at transformer terminals from its rating and impedance.Earthing conductorCalculate a protective conductor thermal minimum using the applicable material, insulation and initial-temperature assumption.Busbar sizingEstimate conductor area from a current-density assumption. Assembly temperature rise and fault strength need separate verification.Standby generator sizingBudget steady-state generator capacity using simultaneous demand, reserve and the manufacturer site-capacity factor.Lighting lumen methodEstimate luminaire quantity and connected load using photometric utilisation and maintenance factors you enter.UPS battery sizingEstimate nominal battery energy and amp-hours from load, runtime, inverter efficiency and usable capacity.Solar PV sizingBudget PV modules, storage and AC inverter capacity separately using site yield and simultaneous peak demand.Geared motor speed & torqueEstimate gearbox output speed and torque from motor power, ratio and efficiency. This does not select a gearbox.Water pumping dutyEstimate hydraulic, shaft and electrical power from required flow and total dynamic head.Development demand scenarioExplore a development load using explicit unit simultaneity, common services and future allowance.CT current conversionConvert a primary current to an ideal CT secondary current. This tool does not recommend protection settings.Motor energy comparisonCompare annual energy for the same shaft duty at two efficiencies, using your hours, tariff and installed replacement cost.Three-phase voltage unbalanceCompare three simultaneous line-to-line RMS readings. This magnitude calculation does not determine relay settings or negative-sequence voltage.DC control power budgetAdd simultaneous DC control loads and an explicit reserve to estimate continuous output watts and amps.Managed EV charging capacityCompare connected charging power with site headroom and your configured EV limit. This assumes functioning load management.CT secondary burdenCompare complete lead-loop and connected device burden with the CT rated burden.TT electrode and RCD checkScreen the RA × IΔn voltage constraint for a TT system; this is not a complete protection assessment.Third-harmonic neutral currentEstimate neutral current from identical, coherent third harmonics on three balanced phases.Capacitor-bank resonance screenEstimate resonance order for a plain capacitor bank and source impedance.Radial feeder fault currentEstimate a downstream three-phase fault using explicit source and conductor impedances.