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:

Monthly Power Factor Adjusted Billing kW

The monthly power factor adjusted billing kW is calculated as follows:

(1) Calculate the Current Month Power Factor Adjusted NCP kW using the following formula - (Actual Monthly NCP kW x 0.95)/Current Month Power Factor.

(2) The Power Factor Adjusted Ratchet kW is determined by finding the highest value of the previous 11 months Power Factor Adjusted NCP kW multiplied by 80%. The Power Factor Adjusted NCP kW for each month is calculated using the actual power factor for that month.

(3) The monthly Power Factor Adjusted Billing kW is then determined by taking the higher of the Current Month Power Factor Adjusted NCP kW as calculated in (1) or the Power Factor Adjusted Ratchet kW as calculated in (2).

Determination of 4CP Power Factor Adjusted Billing kW

The 4CP Power Factor Adjusted kW is calculated as follows:

(1) The average of the retail customer’s 15 minute integrated demand at the times of the ERCOT peaks in June, July, August and September adjusted by the associated power factor from each of those intervals in accordance with the following formula – (Monthly CP x 0.95)/actual power factor at that interval.

This 4CP value will be in effect for the entire calendar year beginning in January of the following year.

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.

For additional information, click here. (Competitive Retailers Only)

To access Oncor tariffs on the Texas Public Utility Commission website, visit http://www.puc.state.tx.us/electric/rates/Trans/Oncor.pdf.

Get Adobe Reader You will need the Adobe Acrobat© Reader to view a .pdf file. To download the FREE viewer, click here and follow the simple instructions.