Power Factor Metering

Power factor is a measure of how efficiently electricity is being used. Maintaining a higher power factor benefits both the customer and the utility, while a lower power factor indicates inefficient use of electrical power. Higher power factors result in greater customer efficiency, lower power delivery system losses, and requires less system capacity to deliver the same load. Implementing the power factor adjustment will encourage customers to maintain a higher power factor, which will increase Oncor’s system capacity and result in fair competition to all customers.

Various types of power are at work to provide us with electrical energy. Listed below are these types of power:

Working Power - The "true" power used in all electrical appliances to perform the work. We refer to working power as kW or kilowatts.

Reactive Power - Inductive load, such as motors, compressors etc. require reactive power to generate and sustain a magnetic field in order to operate. We refer to this non-working power as kvars or kilovolt-amperes-reactive.

Apparent Power - Working power and reactive power make up apparent power, which is referred to as kVA or kilovolt-amperes.

Power Factor (PF) - The ratio of working power to apparent power, or the formula PF = kW / kVA.

Oncor's Tariff (5.5.5 Power Factor) allows for the adjustment of billing demand if the power factor is less than 95%. The power factor that will be used is the average power factor for the 15 minutes during the peak kW demand. The billing adjustment will occur after ratchets, transformer losses etc.

Tariff for Retail Delivery Service - Oncor Electric Delivery Company

5.5.5 Power Factor

If the Power Factor of Retail Customer's load is found to be less than 95% lagging as measured at the Meter, Company may require Retail Customer to arrange for the installation of appropriate equipment on Retail Customer's side of the Meter necessary to correct Retail Customer’s Power Factor between unity and 95% lagging as measured at Meter, or, if Retail Customer fails to correct its Power Factor consistent with this standard, the demand associated with Retail Customer’s use of Delivery Service, as determined in the appropriate Rate Schedules in Section 6.1 RATE SCHEDULES, may be increased according to the following formulas:

(1) Calculation of Power Factor Adjusted NCP kW. The NCP kW applicable under the Monthly Rate section shall be modified by the following formula:
Power Factor Adjusted Monthly NCP kW=(Actual Monthly NCP kW x 0.95)/Current Month Power Factor

(2) Calculation of Power Factor Adjusted 4-CP kW.

Each of the Retail Customer’s monthly coincident peak kW demands used to calculate the Retail Customer’s average 4 CP kW demand applicable under the Monthly Rate section shall be calculated using the following formula:

Power Factor Adjusted Monthly CP kW =(Actual Monthly CP kW demand at the time of the ERCOT peak x 0.95)/Monthly Power Factor

Power Factor Adjusted 4-CP kW=average of the Retail Customer’s Monthly CP kW as adjusted for power factor if applicable.

(3) Power Factor Adjusted Monthly NCP kW demands will be used in determining the Billing kW under the applicable tariff schedule.

If Company has a different power factor billing adjustment it shall conform to these calculations upon its next general rate case.

Should a Retail Customer's Power Factor deviate from the standard described above to the point that it is causing Delivery System problems for other Retail Customers, and the Retail Customer fails to correct the problem after sufficient notice, Company may install the necessary equipment on the Delivery System to correct the problem to the standard described above, and the Retail Customer shall be required to reimburse Company for the cost.

For answers to common questions regarding power factor, visit our power factor Q&A.

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