HVAC Electrical Calculators | Chiller Trend

Electrical

Ohm’s Law & Power

Enter two values to calculate the other two.

Known Values

Voltage Optional

V

Current Optional

A

Resistance Optional

Ω

Power Optional

W

Calculate Reset

Calculated Values

Ohm’s Law result

—

Second calculated value

—

Advanced

Formula: V = I × R. P = V × I. Related forms are used depending on which two values are entered.

Assumptions: Ideal DC and simple resistive-circuit relationships.

Warnings: Measure resistance only on a de-energized circuit. Motors, coils, transformers, and drives require additional electrical relationships.

Electrical

Three-Phase kW

Estimate real power from voltage, current, and power factor.

Electrical Readings

Enter line voltage and line current. Replace the default power factor if measured.

Line voltage Required

V

Line current Required

A

Power factorEnter 0 to 1. Default

PF

Calculate kW Reset

Estimated real power

—

Apparent power

—

Power factor used

—

Advanced

Formula: kW = volts × amps × 1.732 × power factor ÷ 1000.

Assumptions: Voltage and current are treated as balanced three-phase line values.

Warnings: If power factor is estimated instead of measured, calculated kW is also estimated.

Electrical

Current Imbalance

Calculate current imbalance from three phase-current readings.

Phase Current

Enter L1, L2, and L3 current.

L1 current Required

A

L2 current Required

A

L3 current Required

A

Calculate Imbalance Reset

Current imbalance

—

Average current

—

Maximum deviation

—

Advanced

Formula: % imbalance = maximum deviation from average ÷ average current × 100.

Assumptions: All three readings are taken under the same operating condition and are directly comparable.

Warnings: Verify readings with a calibrated meter and compare against equipment-manufacturer limits.

Electrical

VFD Frequency to Motor RPM

Calculate synchronous motor speed and nameplate slip.

Motor and VFD

Enter VFD frequency and motor poles. Add nameplate full-load RPM to calculate nameplate slip.

VFD output frequency Required

Hz

Motor poles

Motor base frequency Default

Hz

Nameplate full-load RPMUsed to calculate nameplate slip at the motor base frequency. Optional

RPM

Reset

Synchronous motor speed

—

Base synchronous RPM

—

Nameplate slip RPM

—

Nameplate slip

—

Advanced

Formula: Synchronous RPM = 120 × frequency ÷ poles. Base synchronous RPM = 120 × base frequency ÷ poles. Slip RPM = base synchronous RPM − nameplate full-load RPM. Slip % = slip RPM ÷ base synchronous RPM × 100.

Assumptions: Nameplate slip describes the rated full-load condition at the motor base frequency.

Warnings: Actual shaft RPM under load depends on operating load, motor characteristics, and VFD control behavior. This calculator does not predict actual loaded shaft RPM at arbitrary VFD frequencies.

Electrical

Transformer VA / Control Amps

Calculate required VA or available control current.

Transformer Inputs

Choose what to calculate, then enter the requested values.

What do you want to calculate?

Secondary voltage Required

V

Load current Required

A

Calculate Reset

Required transformer capacity

—

Secondary voltage

—

Load current

—

Advanced

Formula: VA = volts × amps. Amps = VA ÷ volts.

Assumptions: This uses the basic single-phase volt-ampere relationship for transformer secondary loads.

Warnings: The result does not add sizing margin or account for inrush, duty cycle, simultaneous loads, fuse sizing, conductor sizing, or manufacturer requirements.