kVAR (Reactive Power)

kVAR, kilovolt-amperes reactive, quantifies reactive power the portion of alternating-current power that flows back and forth between source and load without performing useful work. Reactive power is needed to build and maintain the magnetic fields in inductive devices (motors, transformers, chokes) and the electric fields in capacitive devices. It is the foam on the beer: present, real, and something the grid must still deliver and carry, even though it does not turn into heat in your hashboards.

Reactive power and power factor

The ratio of real power (kW) to apparent power (kVA) is the power factor. High reactive power means a low power factor, which forces conductors and transformers to carry extra current for the same useful output. Large commercial and industrial customers are often billed penalties for poor power factor, because the utility must size its infrastructure for the full apparent-power current.

What this means for miners

Modern ASIC power supplies use active power-factor correction, so a well-designed mining load draws very little reactive power its power factor sits near 0.95 to 0.99. That keeps kVAR low and avoids power-factor penalties. The reactive load in a Hashcenter usually comes not from the miners themselves but from cooling fans, pumps, and HVAC motors. Sites with many large motors may add power-factor-correction capacitors to inject leading kVAR and cancel the lagging kVAR of the motors, shrinking the apparent-power current and the bill.

Reactive power, real power, and apparent power together define how efficiently your facility uses the grid. Pair this entry with kVA (apparent power) to see the full triangle.