7 selection criteria of voltage stabilizer

One of the most important problems that we encounter in a power supply network is the frequent fluctuation of supply voltage.

The frequent and sudden changes in voltage can cause various problems, such as increase of maintenance costs, power consumption, destruction of sensitive electronics – and not only them – and generally problems of the equipment of an installation.

The use of the proper stabilizer is a solution of the above problems that are caused by the increase/reduction of voltage. Voltage stabilizers provide at their output, stable supply voltage, securing the uninterrupted and correct operation of the installed equipment.

Which are the selection criteria of the proper stabilizer?

1. High degree of stabilization

Voltage fluctuations put the equipment of an installation under strain. For example, if a machine operates constantly under high voltage, its insulation will age faster than expected, creating an increase to maintenance costs or even the need of a replacement.

The solution to this problem is a voltage stabilizer with high degree of stabilization, so to eradicate the strain that the equipment is under.

The stabilization a voltage stabilizer achieves is measured by its accuracy. The higher the accuracy, the greater the stabilization achieved.

An accuracy if 5% isn’t acceptable, since it can de-stabilize a steady voltage, if the fluctuation of the network’s voltage is lower.

If the stabilizer has high accuracy, around 0.5%, a steady operation of our equipment is secured, in its nominal voltage. As a result, its strain is reduced, so is the need of its maintenance and damages as well as destruction can be avoided, for the entirety or part of the equipment.

High stabilization degree offer both electromechanic and static stabilizers.

2. Stabilization speed

In sensitive data networks, where speed of data transport are great, even a small fluctuation in voltage can cause severe problems in communication, such as incomplete data transfer or destruction of sensitive equipment (e,g, hard drives, servers, PC etc).

A “slow” stabilizer ( in a high speed network) cannot eradicate these problems.

On the other hand, a high speed stabilizer can adjust the voltage fast enough, in order to prevent the problems mentioned above.

But which speed is satisfactory?

A basic rule is that the demanded speed of a stabilizer must be high enough so that the fluctuation isn’t perceived by the equipment.

Static stabilizers have faster stabilization speed in comparison with the electromechanic stabilizers, due to their way of operation. All controls and adjustments are done through digital cards and groups of thyristors, at a static stabilizer.

3. Capability of operating under full load in the entirety of voltage range

Under big fluctuations – more specifically when voltages are small under constant load – the currents that are caused are high. Under these circumstances, the load isn’t changing and steady supply is needed.

the point to be taken into consideration, is that the stabilizer that you will choose must ensure the continuance of the operation under full load, even in the lower limits of the voltage.

Quality electromechanic stabilizer, due to their construction and way of operation, have great tolerance in high currents , in comparison with electronic (static) stabilizers.

Therefore, a quality electromechanical stabilizer effectively ensures continuous operation at full load.

4. Ensure uninterrupted operation of equipment

In case of voltage interruptions, the stabilizer should ensure the correct return of the voltage, achieving the absorption of any accumulated loads. To achieve this, the stabilizer should withstand high strains and be able to operate over full voltage range, under full load.

The interruption of the stabilizer itself is another case of strain on the installation’s equipment. If you have a stabilizer based on relay technology, it creates short interruptions when adjusting the voltage. These small breaks may not be perceived by the human eye, but the equipment understands the momentary variation.

The appropriate voltage stabilizer should be driven by digital microprocessors, which continuously perform control between input voltage and desired voltage, giving timely command for the required stabilization in the voltage regulator.

Voltage stabilizers that ensure uninterrupted operation of the equipment can be either electromechanical or electronic, provided that voltage regulation is not performed via relay.

5. Qualitative voltage at the output of the stabilizer

In addition to constant voltage, the quality of the power supply of the equipment is also influenced by the quality of the voltage. For example, noise insertion is a poor signal quality signal and can destroy measurement results and / or data transfer.

So the stabilizer you choose should ensure that no deformations and no-line noise are introduced.

In general, the above criterion is satisfied by both electromechanical and electronic stabilizers, since voltage stabilization is performed – in both types of stabilizer – by an isolation transformer at the rms value of the voltage.

6. Maintenance needs

An additional criterion that you should consider in choosing a stabilizer is its maintenance needs and costs.

Electronic stabilizers have very small maintenance needs as they do not contain moving parts and consist of digital cards and thyristors.

In electromechanical stabilizers, maintenance needs vary depending on the quality and construction of the stabilizer.

The moving parts of a quality electromechanical stabilizer are made of very good quality materials, which minimizes wear on the insulating materials in the autotransformer that performs the voltage regulation. This also minimizes maintenance needs.

7. Suitability of the stabilizer according to installation specifications

Finally, for selecting the appropriate stabilizer, you should consider the specifications of the line’s voltage, such as its load range, or whether there is a need for symmetrical or asymmetrical stabilization.

Loads requiring stabilization of their input voltage may be from very small, 1kva, to central loads of 8000kva. For the needs of a line that supplies small single-phase loads, a suitable power stabilizer should be selected. Even better is there to be a small increase in selected power so you are covered in the case of line extension.

If the need for the line is for asymmetrical stabilization – always referring to three-phase loads – it should be ensured that it can be covered. In the case, therefore, where one line has more loads than another – for example, in one phase the lighting of a room is connected, and there are three-phase loads connected to all three phases (such as a three-phase motor), the phase with lighting will require a higher current than the others, as shown in the following figure.

For the purpose of proper stabilization, the stabilizer should not be affected by this asymmetry.

Assymetrical stabilization

Also, perhaps the most important part of choosing the right economic solution is the rate of variation that exists in the network / power supply voltage and requires stabilization. In a network with very frequent and large dips, such as industrial areas, large sinking rates (such as up to 35%) and lower surges (such as + 15%) are required.

In conclusion, the ideal is to have a relatively wide variety of stabilizer models, so that the options available according to the specifications of the plant for which the stabilizer is intended are also increased.

Electromechanical stabilizers have a larger variety of input variance models compared to electronic stabilizers.

For more information or clarification on how to choose the right stabilizer for your installation, you can contact us at +30 210 3460222 (Contact Person: Panagiota Vafeiadaki).