Transformers, demand, ATS, busbars, power quality, and generators
Transformer Sizing Calculator
Estimate transformer kVA from connected load, demand factor, future growth, loading margin, ambient derating, and standard rating series.
Open calculatorPower Systems & Distribution
Power-system calculators for transformer capacity, demand, ATS selection, busbar duty, generators, harmonics, and distribution planning.
11 calculatorsTransformers, demand, ATS, busbars, power quality, and generators
Busbar Current Rating Calculator
Estimate busbar current from width, thickness, material, current-density reference, and derating factor.
Open calculatorTransformers, demand, ATS, busbars, power quality, and generators
ATS Selection Calculator
Select a preliminary ATS current rating, PC or CB class, pole arrangement, transfer-speed category, and UPS or STS requirement.
Open calculatorTransformers, demand, ATS, busbars, power quality, and generators
Busbar Short-Circuit Force Calculator
Estimate electrodynamic force between parallel busbars from peak short-circuit current, conductor spacing, and unsupported support span.
Open calculatorTransformers, demand, ATS, busbars, power quality, and generators
Branch Circuit Count Calculator
Estimate branch-circuit quantity from floor area, general load density, circuit voltage and rating, planned loading, dedicated circuits, and optional NEC dwelling circuits.
Open calculatorTransformers, demand, ATS, busbars, power quality, and generators
Electrical Panel Load and Spare Capacity Calculator
Calculate panel kVA, current, utilization, spare amperes, spare kVA, phase-load unbalance, and expansion impact from entered demand loads.
Open calculatorTransformers, demand, ATS, busbars, power quality, and generators
Transformer Impedance Calculator
Calculate transformer full-load current, ohmic impedance, R and X components, X/R ratio, and infinite-bus secondary fault current.
Open calculatorTransformers, demand, ATS, busbars, power quality, and generators
Generator Sizing Calculator
Estimate generator kW and kVA from running load, largest starting step, power factor, reserve, growth, altitude, and ambient derating.
Open calculatorTransformers, demand, ATS, busbars, power quality, and generators
Harmonic and THD Calculator
Calculate THD, total RMS, individual harmonic distortion, triplen content, crest-factor screen, and neutral-current warning from harmonic magnitudes.
Open calculatorTransformers, demand, ATS, busbars, power quality, and generators
Maximum Demand and Diversity Calculator
Combine lighting, socket, HVAC, motor, EV, and other loads with demand and simultaneity factors.
Open calculatorTransformers, demand, ATS, busbars, power quality, and generators
Residential Electrical Load and Service Size Calculator
Estimate dwelling demand, service current, standard service size, spare capacity, and EV charging impact using NEC screening or user-entered demand factors.
Open calculatorDesign the source and distribution path as one system
Power-system planning connects source capacity, transformer and generator behavior, maximum demand, transfer switching, busbar duty, power factor, harmonics, and available fault current.
The objective is to maintain capacity and acceptable voltage across credible operating states, including normal supply, standby supply, starting events, future growth, and faults.
Define the operating scenario before sizing equipment
Connected load, maximum demand, starting load, and emergency load are different quantities. Transformer, generator, ATS, feeder, and busbar sizing should use the scenario that actually governs each item.
Power quality can change equipment current and thermal stress even when kW demand appears acceptable. Harmonics, unbalance, low power factor, and source impedance should be reviewed where non-linear or motor loads are significant.
Applications
Where these calculators fit
Source sizing
Screen transformer and generator kVA, loading margin, impedance, and standby capacity.
Distribution capacity
Estimate maximum demand, feeder current, ATS duty, busbar loading, and future spare.
System performance
Review power factor, fault contribution, voltage regulation, and harmonic exposure.
FAQ
Should a transformer be sized from connected load?
Not automatically. Use justified demand, diversity, future growth, loading policy, ambient derating, harmonic duty, and starting requirements.
Why does transformer impedance matter?
Percent impedance affects voltage regulation and limits secondary short-circuit current, influencing protective-device and busbar duty.
Can an ATS be selected by amperes only?
No. Poles, utilization category, PC or CB class, short-circuit rating, transfer time, source arrangement, neutral treatment, and control requirements also matter.
Explore more
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