Altering Mains Electricity to Obtain Required Voltage

Electrical devices, whether used at home or in industries, have specific power requirements. Such requirements specify power characteristics such as voltage, current, and frequency. These requirements don’t always match the characteristics of incoming power, whether from mains electricity or from other sources, including diesel generators and solar panels.

As such, it is usually necessary to introduce a device to act as an intermediary between the source of power and the device using that power. The intermediary converts power from its original form into the required form. Such a device is known as a power supply unit.

In some cases, power from the source has fluctuating characteristics. For example, due to faults that occur at random within the power grid, mains electricity can be subject to undervoltage and overvoltage.

Due to these fluctuations, the power delivered to a device can be outside the required range. This often leads to damaged electrical appliances or reduced life-span.

Fortunately, with a power stabilizer, the power getting to an electrical load can be regulated, such that characteristics like voltage and current are not only kept constant but also within the optimal range.

Being able to control the characteristics of power getting to your devices can come in handy. Apart from enhancing device safety, it enables you to use your source of power for a wide range of applications.

Let’s look at the devices that enable control over power characteristics.

Power Stabilizer

Such a device comes in handy especially with electrical appliances that are highly sensitive to power fluctuations. These include medical equipment, telecommunication equipment, air conditioners, computers, offset printing machines, industrial machines, and television sets.

Stabilizers are crucial when working with expensive machines because they help prevent damage.

Modern stabilizers provide a digital interface that enables the control of output power characteristics. Output power can be altered according to the different appliances being used and their different power requirements. In this respect, such stabilizers are similar to the programmable power supply, which also provides an interface to control output power characteristics.

How Does it Work? 

A stabilizer typically has 2 operations: buck and boost. The buck operation is carried out when there is undervoltage and the voltage being supplied to the target load has to be increased. The boost operation is carried out when there is overvoltage and the voltage being supplied to the target load has to be reduced.

To perform both operations, a stabilizer usually has a transformer, in addition to switching relays.

There are different combinations of the transformers and switching relays, which are activated according to whether there is undervoltage or overvoltage.

During undervoltage, the transformer will tap power from the source, convert it to the appropriate voltage, then add it to the current before it gets to the load.

During overvoltage, two stage voltage stabilizers may be used in addition to two relays to provide constant power to the load.

Types of Power Stabilizers 

Servo-Controlled

Such stabilizers use a servo motor and the negative feedback technique to facilitate the correction of voltage. A servo-controlled stabilizer will typically have the following components: auto transformer, buck boost transformer, servo motor, motor driver, and control circuitry.

These stabilizers are used when high output accuracy is a priority. They have an output accuracy range of 1%. Meanwhile, they can handle input that has fluctuations of up to 50%.

Relay Type

A relay type stabilizer usually has several tappings of the transformer, which are connected to the load according to whether a buck or boost operation is needed. Voltage regulation is done by switching the relays according to whether the issue is undervoltage or overvoltage.

Components that make up this type of stabilizer include the micro-controller unit, the operational amplifier and the rectifier circuit.

The relay type stabilizer has an output voltage accuracy of 5-10% and can handle input voltage fluctuation of between 6% and 15%.

Such stabilizers are cheap and light-weight, and are preferred for use with low-rating appliances.

They have a number of disadvantages, including low reliability, low durability, inability to withstand high voltage surges, and slow voltage correction.

Static Voltage

Static voltage stabilizers don’t have any moving parts and are usually more accurate than servo-controlled stabilizers. They have the following components: microcontrollers, microprocessor, DSP based controller, buck boost transformer, and an IGBT power converter.

The microprocessor keeps track of input voltage and in case of any variations, sends pulses to the IGBT converter, which then generates the necessary voltage.

The static voltage stabilizer has multiple advantages, including fast correction speed, reliable voltage regulation, lower maintenance costs since all parts are stationary, and small size. It is a popular choice.

Programmable DC Power Supply

A programmable dc power supply allows control over dc output voltage characteristics, with voltage and current being the most commonly controlled characteristics. This control is made possible through a digital interface, which can be accessed both on location and remotely.

On location, there is a keypad for entering the required output voltage characteristics. If you want to control the voltage remotely, you can take advantage of various interfaces, including USB, RS232, and GPIB.

A good programmable power supply must be able to deliver stable power with minimal noise to all types of loads regardless of their resistance, impedance, or inductance.

Most programmable dc supplies have two modes, constant voltage and constant current. The default mode is the constant voltage mode, where the power supply keeps the output voltage constant. The output current is determined by impedance of the load.

In constant current mode, which is considered the safety mode, the power supply keeps the output current constant, with the voltage being determined by the impedance of the load.

In both modes, the output is controlled according to user settings.

The power supply works with the following user-defined settings: maximum current, maximum voltage, and maximum power.

Programmable supply units also offer additional features, including temperature regulation and short-circuit protection.

When considering which power supply to use, factors such as control flexibility, number of outputs, and cooling should be checked.