Educational arithmetic worksheet

Document assumptions. Explore arithmetic. Hand the project to a qualified electrical professional.

This reference tool illustrates motor-current, starting-current, voltage-drop and loss arithmetic from user-entered data. It does not determine cables, protective devices, starters, drives, panel components or installation requirements.

Reference only · Not code compliance · Qualified review required

Interactive reference

Motor feeder arithmetic

Enter project data only when its source is known. Blank evidence inputs cause dependent outputs to be withheld.

Excluded: fault current, disconnection time, earth fault, short-circuit withstand, cable ampacity, derating, installation method, harmonics, protection coordination, local rules, manufacturer compatibility and installation.

1 · Motor arithmetic inputs Motor output

Phase Line voltage (V) Efficiency (%)Enter percent, for example 90 — not 0.9. Use nameplate or manufacturer data. Power factorUse nameplate or manufacturer data.

Calculated current is illustrative arithmetic from these inputs. It is not cable, protection or equipment data.

2 · User-supplied cable data Conductor area being documented (mm²)A record only. The tool never chooses or validates this area. One-way route length (m) AC resistance R (ohm/km) Reactance X (ohm/km) Source basis confirmed?

No resistance, reactance, current-density, ampacity or derating constants are embedded. Both R and X plus source confirmation are required.

3 · Starting and energy arithmetic Starting-method labelA documentation label only; the tool does not choose a method. Starting-current multiplierEnter only from nameplate, manufacturer or project-study evidence. No preset value is supplied. Multiplier source confirmed? Full-load-equivalent annual hours Energy tariff per kWhNo currency is inferred.

I understand this produces educational arithmetic only. It is not suitable for purchasing, equipment determination, wiring or installation. I will refer the final installation to a qualified electrical professional.

Professional handoff

Unrated review checklist

This is a question list, not a bill of materials, quotation or purchasing list. It contains no quantities, ratings or catalog numbers.

Project evidence

Motor nameplate and manufacturer data
Load duty, start frequency and acceleration needs
Supply characteristics and prospective fault current
Cable manufacturer R/X data and route details

Qualified review

Cable construction, installation method and derating
Fault protection, disconnection, earth fault and withstand
Protective device, isolator, contactor, overload, starter or drive coordination
Local rules, enclosure, harmonics, EMC, commissioning and documentation

Method and limits

Arithmetic, not a specification

Full-load current uses entered motor output, voltage, efficiency and power factor. Optional starting current multiplies that value by a user-entered evidence-based factor. Cable voltage drop uses user-entered AC resistance and reactance per kilometre, route length and power factor. Loss uses user-entered resistance. The conductor area is recorded but never used to infer suitability.

No statutory limit, acceptance comparison, equipment rating or installation instruction is produced. Annual energy and cost assume the displayed full-load current for every entered hour and are not a load-profile forecast.

Review sources and evidence boundaries →