TNB power factor surcharge: what triggers it and how to stop paying it

What is power factor?

Power factor is the ratio between real power in kW and apparent power in kVA.

It describes how effectively the electrical current is being used for useful work.

Motors and other inductive loads can draw reactive power as well as real power, increasing current without an equivalent increase in productive work.

This is different from a simple measure of how many kWh the site uses.

TNB's power-factor guidance distinguishes the technical effect from the commercial effect. Low power factor can increase current and stress electrical infrastructure;

the bill may also show a surcharge when the applicable measured condition falls below the required threshold.

A review should therefore establish what the bill is measuring, not rely on a single instantaneous display reading.

What power factor does TNB require?

TNB's official guidance states that customers taking supply at 33 kV or below should maintain power factor at or above 0.85.

For supply at 132 kV or above, the stated threshold is 0.90.

These thresholds must not be applied indiscriminately to an account at another supply condition;

confirm the specific tariff and current billing rule with TNB where the category is unclear.

A medium-voltage industrial site should first check its recorded supply voltage, the power-factor figure on each bill, and whether a surcharge was charged.

Do not assume every site with motors is paying a penalty, or that a brief low-power-factor event necessarily reproduces the billed monthly value.

The commercial assessment needs the period and measurement basis used for that account.

How do I check whether a surcharge is correct?

Keep the original bill and identify the power-factor line, the measured figure, its billing period and the resulting surcharge.

Request clarification from TNB if the calculation basis is not explicit.

Reconcile the amount using the applicable official billing rule rather than treating a headline percentage found online as a complete formula.

Different parts of a surcharge rule may have different application conditions.

Distinguish current-period charges from earlier balances, credits and corrections.

Where detailed reactive-energy or demand measurements are available, compare them with the billed condition using consistent units and meter multipliers.

An unexplained difference may be a data or period issue; it is not automatically proof that a charge should be removed.

Preserve the calculation trail for any query to TNB.

What commonly causes low power factor?

TNB notes that operating motor-based equipment without load or below its recommended loading can contribute to poor power factor.

Sites with changing production schedules may also have compensation that does not match the load throughout the day.

Existing correction equipment can require inspection if switching stages, protection or maintenance conditions have changed.

A bill can identify the issue, but not diagnose every electrical cause.

Review the equipment actually operating during affected periods and whether the load pattern changed recently. Compare quiet shifts, production peaks and shutdown conditions.

Avoid attributing the problem to a specific motor solely because it is the largest item on the floor.

Use suitable measurements and qualified inspection to connect the billed condition with the installation.

Can a capacitor bank stop the surcharge?

Capacitors are a common method of compensating reactive power, and TNB lists them among ways to improve low power factor.

However, buying a bank without checking the installation is not a reliable bill-review recommendation.

The appropriate size, switching arrangement, harmonic conditions and protection depend on the actual load.

An existing bank may need repair or adjustment rather than complete replacement.

Correction should be designed and implemented by qualified electrical professionals. Avoid overcompensation and do not change protection or switching settings without an assessment.

A tariff review can quantify the surcharge currently being paid and identify the case for further investigation;

it should not present an unmeasured equipment proposal as a guaranteed technical solution.

Will correction also lower my kWh or maximum demand?

Keep each cost mechanism separate. Avoiding a power-factor surcharge is not the same as using less real energy or reducing the billed maximum demand in

kW. Improving current conditions may have technical benefits, but their value must be demonstrated using the relevant measurements.

Do not add a projected demand saving to a surcharge saving if both calculations are really describing the same assumed improvement.

A sound business case identifies the recurring surcharge that can reasonably be avoided, the cost of inspection, repair or new equipment, and the expected maintenance

requirements. It also states what has not yet been measured.

Compare the corrected condition over representative operating periods rather than assuming that a satisfactory reading during commissioning proves the full year's financial outcome.

How do I prevent the surcharge from returning?

After corrective work, check subsequent bills and retain the before-and-after measurements. Revisit the assessment when production schedules, major motors or power-electronic equipment change.

Follow the electrical professional's maintenance recommendations for installed correction equipment.

Billing evidence should confirm the commercial outcome, while measurement and maintenance records confirm that the technical condition is being managed.

Rukan reviews power factor alongside tariff fit, maximum demand and billing accuracy.

Our bill review can establish whether a surcharge is recurring and whether it warrants a technical investigation. We are not tied to selling equipment;

any affiliated supplier relationship would be disclosed. Upload available TNB bills on the homepage, and decide about implementation only after seeing the findings.