CSLB C-46 Solar ContractorSolar Thermal System InstallationMedium
A solar thermal installer is connecting a circulation pump to the electrical supply for a 240V, 60Hz system. The pump's nameplate indicates it draws 0.75 Amps and has a power factor of 0.85. What is the apparent power (VA) of this pump?
- A153 VA
- B180 VA
- C204 VA
- D240 VA
Show answer & explanationAnswer & explanation
Correct answer: B. 180 VA
Apparent power (VA) is calculated by multiplying voltage (V) by current (A). The power factor is used to calculate real power (Watts), not apparent power. So, 240V * 0.75A = 180 VA.
Why the other options are wrong
- A. Incorrect. This would be 240V * 0.75A * 0.85 (real power, not apparent power).
- C. Incorrect. This would be 240V / 0.75A or some other incorrect calculation.
- D. Incorrect. This is the voltage, not the apparent power.
Apparent Power (VA)
Apparent power is the product of the RMS voltage and RMS current in an AC circuit, measured in Volt-Amperes (VA). It represents the total power delivered to a circuit.
- Calculated as Voltage × Current (V × A).
- Includes both real (working) power and reactive (non-working) power.
- Used for sizing electrical components like transformers and wiring.
Memory trick: Voltage times Amps, that's VA's ramps.