powerfactor improvment

How to improve the power factor?

It’s quite simple. By installing capacitors or capacitor banks. Improving the power factor of an electrical installation consists of giving it the means to “produce” a certain proportion of the reactive energy it consumes itself.

The capacitor is most frequently used, given:

1. Its non-consumption of active energy
2. Its purchase cost
3. Its ease of use
4. Its service life (approximately 10 years)
5. Its low maintenance (static device)

          Power diagram   📐📏

Power factor is the ratio of working power to apparent power. It measures how effectively electrical power is being used.

Low power factor means you are not fully utilizing the electrical power you're paying for.

A high power factor signals efficient utilization of electrical power, while a low power factor means poor utilization of electrical power..  

To determine power factor (PF), divide working power (kW) by apparent power (kVA). In a linear or sinusoidal system, the result is also referred to as the cosine θ.

                 PF = kW / kVA = cosine θ kVA

For example, if you had a boring mill that was operating at 100 kW and the apparent power consumed was 125 kVA, you would divide 100 by 125 and come up with a power factor of 0.80.                            

                     (kW) 100 / (kVA) 125 = (PF ) 0.80

• P – Active power
• S1 and S2 – apparent powers
  (before and after compensation)
• Qc – capacitor reactive power
• Q1 – reactive power without capacitor Q2: reactive power with capacitor

     How to calculate the power of capacitors

Based on electricity bills to calculate the capacitor banks to be installed, use the following method:

• Select the month in which the bill is highest (kVArh to be billed)
• Assess the number of hours the installation operates each month
• Calculate the capacitor power Qc to be installed

Qc = kVArh to be billed (monthly) / No. of hours’ operation (monthly)

1. Example for the subscriber 

• Highest reactive energy bill: December Number of kVArh to be billed: 70,000
• Monthly operating times: High-load + peak times = 350 hours

                 Qc (bank to be installed) = 70,000 / 350 = 200 kVAr

source:  http://electrical-engineering-portal.com