Tips for saving energy with capacitor banks

Discover how to make significant energy savings by installing capacitor banks.

In this article I will try to explain why putting capacitor to compensate for electrical installations, ie reactive energy installations , which at a certain scale our supply company in the bill penalizes us. But the drawbacks in certain facilities that often are unknown capacitor by placing.

But before that let us to describe the following concepts, who are we call active energy and reactive energy:

1º Active Energy.

Electric machines convert alternating current electrical power supplied to mechanical work and heat. This energy is measured in kWh and is called active energy.

All receptors that absorb only such power are called resistive.

2No reactive power.

There are other receivers, non-resistive, magnetic fields required for operation (transformers, engines ...) and other energy consuming called reactive. These inductive loads are called and what they do is absorb energy from the grid during the creation of magnetic fields that need to operate and deliver for the destruction of the. This causes losses in the conductors, voltage drop in the same and additional power consumption that is not directly usable by receivers.

To give an example of the above and can better understand this (people, who are not stuck in the electrical world), I'll give an analogy I saw in a presentation but mark well the idea. Imagine a beer mug filled, evidently, beer with foam spray. Well active energy (useful energy) would be the part of the pitcher of beer, while the reactive power (unusable) the foam would jug.

If we eliminate from our facility you would have wasted energy full capacity of the jar to useful power.

The connection of inductive loads in a facility making is that there is a mismatch between the wave intensity and tension, the angle measured this gap and indicates the relationship between reactive and active current intensity thereof, therefore cos? indicates the relationship between active power and apparent power of the installation (KVA ie that can be consumed in a facility than).

Thus , the output of a system increases as cos improves?

Power companies penalize reactive power consumption in order to encourage their correction for the maximum surcharge if the cos? = 0.5 or inferior; no charge for cos? = 0.95 or even bonus with cos? = 1.

This correction is achieved by installing the reactive capacitor bank.

The advantages of placing a capacitor bank installation in addition to the cost savings that we will provide on electricity bills, is going to allow us to have a more optimal installation. For example overloaded transformers will not loose if not more potential, will be reduced by losses in cables installation and even the switch could put a smaller caliber with the economic cost that this implies.

But they also have a downside. Let's see which are.

Most electronics today feed today what we call non-linear loads, receptors that is fed by power electronics such as variable speed drives, rectifiers , converters etc ... other charges as saturable reactors, Welding equipment, ...... arc furnace installation harmonics injected.

Called harmonic waves of voltage or current whose frequency is several times the fundamental frequency of the network (50Hz). Well these harmonics are harmful to the system can produce unwanted tripping of protective conductor overheating, on currents in the installation ......

Placing a capacitor bank in an installation with harmonics it does is amplify the same. (The battery does not generate harmonics, however it can amplify existing harmonics aggravating the problem).

On the other hand the capacitor bank is a more sensitive to harmonics since it presents a low impedance at high frequencies and absorbs all harmonic currents reduce the lifetime of the capacitors.

However, do not worry ... because there are solutions to this problem. Or use passive or active filters to remove harmful harmonics, (which usually can be expensive) or live with them. On this last point then you have to choose a capacitor bank with oversized cans voltage or battery that embody some filters or tuned inductance (usually of 215 speed , Manufacturers depends).

Summarizing:

It is desirable to optimize the installation and save on the use of capacitor banks, but also to do a study or measurement of harmonics that can have the facility to set the right battery, because otherwise we would save time in the bill but agrandaríamos other installation problems. ( with the problem of premature battery aging)

If the measurement of the electrical installation gives the following parameters in voltage distortion (THD U%):

• THD U <2% using a standard battery.
• THD U del 2% to the 3% choose a battery with oversized pots in voltage 440v or 470V
• THDU 3% to the 5% battery use anti harmonic inductances.

 

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