Power Factor

<p>Power factor is the cosine of the phase angle between voltage and current waveforms in an AC circuit. A power factor of 1.0 (unity) means all current drawn is doing useful work. A power factor below 1.0 means a portion of the current is reactive — it circulates between source and load without transferring energy.</p><p>Data centre IT loads typically present a power factor of 0.95–0.99, which is near-unity. UPS systems and generators must be sized in kVA, not kW, so a 1 MW IT load at 0.95 PF requires a UPS rated at approximately 1.05 MVA. Poor power factor on non-IT loads (older CRAC units, lighting) can increase distribution losses and penalise tariffs.</p>