Tuesday, February 22, 2011

Power Factor (In Detail) #3

Related Posts
Power Factor #1
Power Factor #2

From our previous discussion we saw that Power Factor can be defined in 3 definitions. ie
  • The cosine of an angle between Voltage (V) and Current (I)
  • True Power / Apparent Power
  • Resistance / Impedance
Please note that in the above expressions, the value of Power Factor can never be greater than 1. A good power factor is always 0.9 or 0.89

In this post we are going to look into detail the Power Factor of angle between Voltage(V) and Current (I)

The power factor PF is mathematically defined as the cosine of the phase angle between voltage and current. True power is defined by the equation . The graphical representation produces a product of the voltage and current. This product is represented as a sine wave, which is twice the frequency of the voltage and current and represents the instantaneous power and its direction. If the power sine wave is completely on the positive side of the axis, it shows that the power in the system is traveling only in one direction, toward the load.

The area under this power sine wave curve represents the amount of energy delivered to the load. If the power sine wave is shifted, the difference in area between the positive and the negative sides represents the power delivered to the load. The negative side of the power sine wave represents the reflected power from a reactive load.

A lagging power factor is one in which the current is lagging behind the voltage and is characteristic of an inductive load.

A leading power factor is one in which the current is leading the voltage and is characteristic of a capacitive load. If the phase angle were to be shifted to be greater than 90 degrees in either direction, the load would effectively become the source.

Power Factor Correction
A power factor of one (1) or "unity power factor" is the goal of any electric utility company since if the power factor is less than one (<1) , they have to supply more current to the user for a given amount of power use. In so doing, they incur more line losses. They also must have larger capacity equipment in place than would be otherwise necessary. As a result, an industrial facility will be charged a penalty if its power factor is much different from 1.

Industrial facilities tend to have a "lagging power factor", where the current lags the voltage (like an inductor). This is primarily the result of having a lot of electric induction motors - the windings of motors act as inductors as seen by the power supply. Capacitors have the opposite effect and can compensate for the inductive motor windings. Some industrial sites will have large banks of capacitors strictly for the purpose of correcting the power factor back toward one to save on utility company charges.

Saturday, February 12, 2011

First Green Energy Centre to be set up in Nairobi, Kenya

Kenyans are set to reap the rewards of a new initiative to help local companies develop and set up climate friendly technologies that will create thousands of jobs.
World Bank’s Special Envoy for Climate Change Andrew Steer announced that the world’s first Climate Innovation Centre (CIC) will be established in Nairobi.

Mr Steer made the revelation yesterday during a conference at the Danish Embassy, Nairobi, dubbed "Green Growth in Kenya" which will focus on the private sectors role in promoting green growth in the context of the country’s changing climate.

The CIC is spearheaded by the Royal Danish Embassy and the Banks Information for Development Program and is expected to help Kenya’s private sector boost industry competitiveness, job creation and cut effects of climate change.

Climate technology
"The creative spark of private Kenyans and African entrepreneur can transform climate challenges into market opportunities. This Climate Innovation Center will provide the help to make it happen," he said.In the first five years, the CIC is expected to create more than 70 climate technology businesses, generating some 4,600 direct and indirect jobs.

"The private sector has a pivoted role in the economy, contributing to 80 per cent of Kenyans GDP. It is expected that 1.7 million informal SMEs will be assisted by CIC," said Geert Aagaard Anderson, the Danish Ambassador to Kenya.Meanwhile, Prime Minister Raila Odinga has said Kenya must take a green development path if it is to realise faster economic growth.He said the energy sector, which drives the country’s economic growth, has the potential to generate renewable energy of up to 7000MW, if fully exploited.

Tuesday, February 8, 2011

Kenya to build local power transformer plant

Kenya is set to construct the first electricity transformers manufacturing plant in the region to boost electricity distribution in the country.
According to the Kenya Power and Lighting Company the plant will manufacture and assemble transformer for local as well as regional market.

In a paid up advert in local dailies the company is calling interested firms to help in carrying out a study on the viability of such a project.

Late last year the company raised 9.8 billion shillings through a rights issue, which KPLC says was meant for upgrading its systems in the country.

KPLC has invited prequalification bids for a viability study on building a local transformer manufacturing plant to help meet the country's growing demand for power.

 Kenya suffers regular power failure owing to insufficient electricity generation capacity and a dilapidated transmission network which have been largely blamed on investor flights and high power bills.....