[Technical Article] Capacitors for power factor correction: what really matters in Low Voltage

Most problems related to the power factor correction do not start where many believe. They are not usually in the regulator, nor in the box, nor even in the initial design of the battery. They start at the same point almost always: in the capacitors. And what is striking is that this continues to surprise, when the capacitor is, without a doubt, the essential element of any low-voltage capacitor battery. Without it, there is simply no battery. In practice, the capacitor is also the component that suffers the most. It works continuously, tolerates constant maneuvers, and ages silently until the system stops correcting as it should. And when that happens, the penalty appears on the bill long before anyone looks inside the box. Because Francesc Fornieles, Product Manager of Power Quality.

The real role of the capacitor in a BT capacitor battery

Capacitors are directly responsible for compensating for the inductive reactive energy generated by motors, transformers, and power electronics. Each stage of the battery is connected and disconnected based on demand, making the capacitor a component subjected to constant stress.

On the field, this translates into a very clear reality: the battery may be “running,” but it is not. correcting well.

When measured in detail, it is common to find capacitors that have gradually lost capacity. They haven't failed all at once; they simply no longer deliver what they should.

Why capacitors are the element that degrades the most

The wear of the condenser is not random. There are factors that repeat themselves over and over in real installations:

• High temperature, due to poor ventilation of the box or demanding environments
• Frequent maneuvers, Especially in installations with variable loads
• Presence of harmonics, Increasingly common due to the use of inverters and power electronics

These three factors, combined, explain the majority of premature failures in BT capacitors.

One of the most common mistakes is to think that if the battery is new or “branded”, these problems won’t appear. Experience shows just the opposite: the installation environment matters more than the catalog.

Maintaining the capacitors makes a difference

Here we see one of the key factors that have the most impact on the profitability of a capacitor battery. Unlike what many people think, A battery of capacitors is not a maintenance-free device.

Basic, well-planned maintenance allows:

• Detecting loss of capacity before it affects the body φ
• Replace only the deteriorated capacitors
• Significantly extending the battery life
• Improving the return on initial investment

In practice, it is not necessary to replace the entire battery when it stops functioning properly. In most cases, it is sufficient to act on the capacitors.

Is it really necessary to replace the entire battery?

No. And this point is critical both technically and economically.

Many batteries are replaced completely when:

• The regulator is working
• The painting is in good condition
• The protections remain valid

The real problem usually lies in the capacitors. Replacing only the deteriorated elements is, in many cases, the most logical and cost-effective option.

Standard batteries vs. customized solutions

A capacitor battery is, in essence, a relatively simple electrical circuit. Therefore, in many countries, installers and electricians opt for customized solutions adapted to the actual installation.

This approach allows:

• Better adaptation to harmonics
• Greater control over design
• More room for the installer
• More added value for the customer

In many countries, particularly Spain, the standard and quick solution still predominates, although it is not always the most appropriate in the medium and long term.

Power capacitors at BT: the importance of the supplier

At this point, having a provider that understands how the actual facilities work is key. In Vector Energy We supply low-voltage power capacitors designed for:

• Replacement of degraded capacitors
• Maintenance of existing batteries
• New paintings and custom-made solutions

If you are considering maintenance, an expansion or a new installation, you can directly consult our solutions and receive technical advice tailored to your case.

👉 Power capacitors at BT – Vector Energy
https://vectorenergy.com/product/condensadores-de-potencia-bt/