Eliminate fees by improving efficiency
Are you a commercial customer using large equipment in your facility? Do you know how efficiently your equipment is running? Did you know that you could be getting charged a Reactive Power fee if your facility’s power factor (efficiency rating) is below 95%? Learn how to find out if the equipment in your facility is running efficiently, and how to improve efficiency.
What is Reactive Power?
Reactive power is the non-working producing power that’s required to magnetize and start up equipment. And it’s one of the most significant ways that electricity is lost when it travels along power lines
The more reactive power that you use, the more energy the electric system loses. This results in the use of larger equipment on the distribution system that otherwise would be unnecessary.
Fortunately, you can reduce reactive power, and your utility bill, by improving your Power Factor.
What is Power Factor?
Power factor is a way of measuring how efficiently electrical power is being used within a facility’s electrical system by looking at the relationship between three components in an AC circuit:
- Real power (kW) – the work-producing power that’s used to actually run the equipment
- Reactive power (kVAr) – the non-work producing power that’s required to magnetize and start up equipment
- Apparent power (kVA) – the combination of real power and reactive power
In an AC circuit, power is used most efficiently when the current is aligned with the voltage.
However, most equipment tend to draw current with a delay, misaligning it with the voltage. What this means is more current is being drawn to deliver the necessary amount of power to run the equipment. And the more an equipment draws current with a delay, the less efficient the equipment is.
How Do I Calculate My Power Factor?
Formula Method: The best way to calculate power factor is by using the following formula:
Here’s a power factor rating of less than 95%, which means the customer would be responsible for a reactive power charge.
Maximum Real Power for billing period = 1,000 kW
Reactive Power at the time of maximum kW demand = 750 kVAr
Apparent Power = SQRT [(1,000 kW)2 + (750 kVar)2] = 1,250 kVA
Because the power factor is below 95%, a charge of $0.40 per kVar is applied to the bill. To lessen the charge, PCLP subtracts 1/3 of the kW (real power) when calculating for billable kVar (reactive power), as shown below.
Billable kVar = 750kVar – 1/3(1,000) = 416.7 kVar
Reactive Power charge = 416.7kVar X $0.40 = $166.68
Cosine Method: Another way to get the power factor is by getting the cosine of the power factor angle.
How Do I Improve Power Factor?
- Minimize operation of idling or lightly-loaded motors.
- Avoid operation of equipment above its rated voltage.
- Replace standard motors as they burn out with energy-efficient motors. Power factor is also significantly affected by variations in load. A motor must be operated near its rated capacity to get the highest power factor.
- Install capacitors in your AC circuit. (illustration below shows how capacitors can help correct your power factor)
Motor running without capacitors
Without a capacitor, the motor is pulling reactive power from the electric grid. The more this power has to travel to reach the motor, the more it gets wasted due to losses along the way. This ultimately leads to a lower power factor and higher electricity bills when the power factor is below 95% at the facility.
Motor running with capacitors
On the other hand, an installed capacitor provides the reactive power that is needed to start up and magnetize the motor, thus eliminating the need to get it from the electric grid. Since you’ll be using less electricity from the grid, you’ll have a higher power factor and lower electricity bills.