Free electrical engineering tools
Turn electrical inputs into usable design parameters.
A connected set of engineering calculators for circuit protection, motor control, surge protection, voltage monitoring, and solar DC applications.
Guided workflow
The JUTRION calculation chain
Move from source and load data to protection parameters through smaller checks that can be reviewed independently.
Engineering calculators
Find the right calculation
Circuit protection
Short-Circuit Current & Icu Calculator
Estimate transformer-secondary terminal fault current, then compare it with the breaker breaking capacity at the operating voltage.
Optional: upstream contribution and feeder impedance for a fuller result.
Open calculator →Circuit protection
Circuit Breaker Sizing Calculator
Calculate design current and screen a standard breaker rating against the cable current-carrying capacity.
Separated: B, C, or D curve suitability is checked in the inrush tool.
Open calculator →Circuit protection
MCB Inrush & Curve Checker
Compare equipment inrush and available fault current with the magnetic-trip bands of B, C, and D curves.
Not a guarantee: final performance follows the exact manufacturer curve.
Open calculator →Surge & voltage
SPD Parameter Selection Check
Translate supply arrangement, installation point, lightning exposure, and equipment withstand into a preliminary SPD requirement.
Important: Up is a coordination target and product value, not calculated from voltage alone.
Open calculator →Motor & switching
ATS Sizing Calculator
Convert the load into design current, the AC-31/AC-33 category, a standard ATS rating, and the pole configuration.
Decision: switched neutral and poles depend on the earthing and source.
Open calculator →Motor & switching
Generator Capacity for ATS
Estimate generator kW and kVA from diversified running load, the largest starting step, reserve, and environmental derating.
Required: confirm voltage dip and transient with the generator maker.
Open calculator →Circuit protection
Breaker Accessory Power Calculator
Estimate control-supply demand for shunt trips, undervoltage releases, motor operators, and related breaker accessories.
Compatibility: series, frame, AC/DC, contacts, and mounting must match.
Open calculator →Circuit protection
AFDD Requirement & Selection
Collect circuit and market information to define an AFDD or integrated AFDD-RCBO requirement and architecture.
Not universal: whether AFDD is required depends on local rules.
Open calculator →Solar & DC
PV String Voltage Calculator
Calculate cold-condition string open-circuit voltage and screen the module count against inverter voltage limits.
Required: use module and inverter datasheet limits.
Open calculator →Solar & DC
PV DC ATS Calculator
Calculate DC design current and organize the voltage, pole, source, and transfer requirements for a solar or battery DC ATS.
DC-specific: verify switching, isolation, and arc interruption at Vdc.
Open calculator →Solar & DC
DC MCB & MCCB Rating Calculator
Calculate DC design current and screen rated current, operating voltage, poles, cable capacity, and breaking capacity.
Critical: DC poles and series connection follow the breaker documentation.
Open calculator →Solar & DC
PV String Fuse Rating Calculator
Calculate a reference gPV fuse-current range and compare it with the module maximum series-fuse rating.
Standard route: design multipliers selectable for the applicable standard.
Open calculator →Solar & DC
PV Combiner Box Rating Calculator
Aggregate string current and voltage into reference input-fuse, output-device, busbar, isolator, and SPD requirements.
System tool: ratings remain subject to enclosure temperature.
Open calculator →Solar & DC
PV DC Isolator Rating Calculator
Screen minimum voltage, current, utilization category, and pole configuration for a PV array isolation point.
Product-specific: verify the switching configuration at Vdc.
Open calculator →Solar & DC
PV SPD Minimum Ucpv Calculator
Derive a minimum continuous operating voltage from the cold-condition array voltage, then screen SPD type and connection topology.
Do not use nominal: the max temperature-corrected Voc governs.
Open calculator →Motor & switching
AC Contactor Motor Sizing
Estimate motor full-load current and a preliminary AC-3 operational-current requirement for normal starting and stopping duty.
Product stage: coil, poles, auxiliaries, and life are selected after.
Open calculator →Motor & switching
Motor Overload Relay Setting
Translate motor nameplate current and application duty into a preliminary overload setting and trip-class check.
Motor data governs: use the nameplate current for final adjustment.
Open calculator →Surge & voltage
Voltage Threshold & Delay Setting
Build a preliminary voltage window, trip delay, and reconnection delay from the equipment tolerance and application behavior.
Application setting: delay rides through disturbances, not calculated from load.
Open calculator →Power distribution
Load Current & Power Calculator
Convert between kW, kVA, and current for DC, single-phase, and balanced three-phase loads.
Supports: preliminary sizing for breakers, ATS, contactors, CTs.
Open calculator →Power distribution
Cable Voltage Drop Calculator
Estimate conductor voltage drop and percentage loss for DC, single-phase, and three-phase circuits.
Boundary: resistance and reactance must match the conductor.
Open calculator →Power distribution
Cable Derating & Iz Calculator
Combine correction factors and check whether the corrected cable capacity remains above the selected breaker rating.
Required: base ampacity and factors from the adopted wiring tables.
Open calculator →Power distribution
Transformer Current Calculator
Calculate transformer line current on both sides from the kVA rating, voltage, and phase arrangement.
Supports: preliminary CT, ATS, MCCB, and ACB planning.
Open calculator →Power metering
CT Ratio & Burden Calculator
Select a reference CT ratio and estimate total secondary burden from meters, relays, and connecting leads.
Product check: accuracy class and saturation need the exact CT data.
Open calculator →Circuit protection
RCCB & RCBO Parameter Check
Organize residual-current waveform, protection purpose, load current, and expected standing leakage into a preliminary requirement.
Code dependent: sensitivity and selectivity follow the market rules.
Open calculator →Circuit protection
ACB Frame & LSIG Worksheet
Build preliminary frame-current and LSIG setting ranges from feeder load, conductor capacity, fault level, and coordination.
Coordination study: final settings need manufacturer curves.
Open calculator →After the calculation
Have the parameters but still need a suitable product?
Send the calculation summary to JUTRION when you need help checking an available configuration for the destination market.