Quick Facts
What Power Factor penalty is
Power Factor (PF) penalty is a financial charge applied to HT and large LT consumers whose power factor falls below a threshold (typically 0.95). The penalty multiplies the standard demand charge by a percentage for each 0.01 PF reduction below the threshold.
The mechanism incentivises consumers to maintain good power factor, which reduces network losses and improves grid efficiency.
Two billing approaches handle power factor:
PF penalty approach: Bill on kWh with separate penalty for poor PF. Used in some states.
kVAh billing approach: Bill on apparent energy directly, capturing PF impact. Used in Maharashtra, Gujarat, Karnataka, and others.
States have largely moved toward kVAh billing as it simplifies administration. Where PF penalty still applies, the calculation and impact are similar.
How PF penalty is calculated
Standard formula:
PF Penalty = Demand Charge × Penalty Rate × (Threshold PF - Actual PF) × 100Where:
Demand Charge is the standard monthly demand charge.
Penalty Rate is the percentage per 0.01 PF (typically 1% to 2%).
Threshold PF is typically 0.95.
Example for an HT consumer:
Contract Demand: 500 kVA.
Demand Charge: Rs 350 per kVA per month = Rs 1,75,000.
Recorded PF: 0.85.
Threshold: 0.95.
Penalty Rate: 1.5% per 0.01 PF.
Penalty: 1,75,000 × 0.015 × 10 = Rs 26,250.
Total Demand Charge: Rs 2,01,250 versus Rs 1,75,000 at PF 0.95.
The penalty of 15% on demand charges is meaningful enough to justify PF correction investments.
Why PF penalty exists
DISCOMs incur additional costs when consumers operate at poor PF:
Higher line losses: Reactive current flows through the network, increasing I²R losses.
Reduced grid capacity: Network conductors are sized for kVA; poor PF reduces effective kW capacity.
Voltage regulation issues: Reactive power impacts grid voltage.
Reduced transformer capacity: Transformers are rated for kVA, so poor PF reduces effective service capacity.
The PF penalty internalises these costs to the consumer, incentivising them to maintain good PF through capacitor installation or load management.
States with PF penalty (versus kVAh billing)
Approach varies by state:
States with PF penalty (separate calculation):
Uttar Pradesh (UPPCL).
Bihar (BSPHCL).
Rajasthan (JdVVNL, AVVNL, JVVNL).
Odisha (DISCOMs).
West Bengal (WBSEDCL).
Several Northeast states.
States with kVAh billing (PF captured directly):
Maharashtra (MSEDCL).
Gujarat (GUVNL DISCOMs).
Karnataka (BESCOM, others).
Tamil Nadu (TANGEDCO).
Andhra Pradesh.
Telangana.
Madhya Pradesh.
Delhi (BSES, Tata Power Delhi).
The trend has been toward kVAh billing, but several states retain PF penalty.
How PF is measured
By the trivector meter at the consumer’s connection:
The meter measures real power (kW) and apparent power (kVA) continuously.
PF is calculated as kW/kVA.
Monthly average PF (or worst-case PF in the period) is recorded.
For HT consumers, Class 0.5S or higher accuracy meters provide precise PF measurement.
Some meters report multiple PF metrics:
Average PF over the billing period.
Lowest PF in any sampling period.
PF for peak demand period.
PF for energy consumption period.
The specific metric used for penalty calculation depends on the state SERC’s tariff order.
How to maintain good PF
Power factor correction equipment:
Fixed capacitor banks: Sized for the average reactive power demand. Provide baseline correction but cannot adjust to varying load.
Automatic Power Factor Correction (APFC) panels: Dynamically switch capacitors based on real-time load. Maintain PF at target (typically 0.97 to 0.99) across changing load.
Solid-state PF correction: Premium electronic correction for rapid load changes. Used in some industrial applications.
Other strategies:
Replace inductive loads: LED lights (replacing fluorescent), variable frequency drives (replacing across-the-line motor starters).
Process optimisation: Avoid running large motors at partial load. Use proper motor sizing for actual loads.
Load management: Stagger large motor startups to avoid coincident reactive power demand.
For most HT facilities, APFC panels with capacitor banks of 200 to 1000 kVAR are standard.
APFC panel sizing and cost
APFC panel sizing for HT facilities:
Survey the facility’s reactive power demand range.
Size capacitor bank to provide reactive power for highest expected reactive demand.
Typical sizing: 0.3 to 0.7 times the kW demand.
For a 500 kW facility: 150 to 350 kVAR APFC panel.
Cost:
200 kVAR APFC panel: Rs 1.5 to Rs 3 lakh.
500 kVAR APFC panel: Rs 3 to Rs 6 lakh.
1000 kVAR APFC panel: Rs 6 to Rs 12 lakh.
Installation:
Located in the electrical room near the meter.
Connected to the LT or HT bus depending on capacitor type.
Wired with detuned reactors for harmonic stability.
Earthing and protection per code.
Payback:
For HT consumers paying PF penalty or kVAh on poor PF: 6 to 18 months.
For consumers without PF penalty: longer payback (no direct savings, only operational benefits).
Common PF penalty mistakes
Treating PF as fixed. PF varies through the day with load mix.
Installing fixed capacitor banks without APFC. Leads to overcompensation at light loads.
Skipping detuning reactors. Pure capacitors interact poorly with harmonics, causing damage.
Ignoring maintenance. Capacitor banks degrade; failed capacitors stop providing correction.
Missing the threshold. Operating just below threshold (0.94 instead of 0.95) triggers full penalty.
Best practices
Target PF of 0.97 to 0.99 for safety margin above threshold.
Install APFC panels for automatic correction.
Include detuning reactors for harmonic stability.
Maintain capacitor banks annually. Failed capacitors should be replaced promptly.
Monitor PF monthly through bill review or SCADA.
Coordinate with DISCOM on PF measurement methodology and any disputes.
Standards and references
PF penalty is governed by state SERC tariff orders. Capacitor banks comply with IS 12672 (power capacitors) and IEC 60931. APFC panels follow industry standards for low-voltage switchgear (IS 13947).
Related glossary terms
- Power Factor
- Trivector Meter
- kVAh Billing
- Contract Demand
- Maximum Demand Penalty
- HT vs LT Connection
- DISCOM
Key takeaways
Power Factor (PF) penalty is a financial charge applied to HT and large LT consumers operating below the PF threshold (typically 0.95). The penalty multiplies the demand charge by 1% to 2% per 0.01 PF below threshold. For HT consumers at PF 0.85, the penalty can add 15% to 20% to demand charges. APFC (Automatic Power Factor Correction) panels with capacitor banks maintain PF above threshold and pay back in 6 to 18 months. States are progressively moving to kVAh billing as an alternative that captures PF impact through apparent energy billing.