The most common methods are:

CVT: the voltage is controlled through a ferro-resonant transformer. Suitable for small capacities where running load is around 80% of rated capacity, losses are high during low loading.

Switching/tap-changing transformer: the voltage is corrected by switching the taps in a transformer. This is a slow method and generates switching surges.

Servo-Voltage stabiliser: the voltage is compensated through a series buck-boost transformer by injecting a compensating voltage. The compensating voltage is tapped from an auto-transformer/ dimmer by a moving carbon brush. The carbon-brush movement is controlled through a servo-motor or a DC motor. Being an electro-mechanical device, the rate of correction is slow, in seconds. The brush movement can generate sparks & electrical noise.

UPS: the incoming power is converted from AC (alternating current) to DC (direct current) to store electrical energy in a battery. In the event of a power outage or voltage fluctuation, the UPS needs to provide power to connected devices. This is where the second conversion from DC to AC comes into play. An inverter is used to convert the stored DC power back into AC power, which can then be supplied to the connected equipment.

Static Voltage regulator: SVR is an electrical device that maintains stable output voltage despite voltage fluctuations or variations in the input voltage. Since a static stabiliser uses electronics it has fast correction speed. Static voltage stabilisers are commonly used to protect sensitive devices from voltage-related issues, such as voltage sag and swell, spike, electrical noise,voltage unbalance and voltage fluctuation.

Speed and Precision: Static voltage stabilisers can respond to voltage fluctuations extremely fast, real-time, within 1 waveform, i.e. few milliseconds. This rapid response ensures that sensitive/modern electronic equipment receives a stable and precise voltage supply, minimising the risk of damage.

Efficiency: They are energy efficient as they do not consume power to adjust voltage levels. They are only active when there is voltage deviation.

Compact Size: They are typically compact and lightweight.

Noise Reduction: Static voltage stabilisers have in-buit noise filters to reduce electrical noise and interference.

Surge Suppression: Static voltage stabilisers have in-buit surge suppressors of Class II.

Total Load Requirement : Determine the total electrical load in each phase that the voltage stabiliser will be supporting. Make sure the load is equally distributed on each phase, consider the capacity of the static voltage regulator as times of the highest loaded phase. Sum up total load in VA.

Peak Current : Consider the peak current or inrush current when the machine starts up. The stabiliser should have enough capacity to handle these temporary spikes without bypass.

Voltage range : Know the range of voltage fluctuations in your area.the stabiliser’s capacity should be sufficient to regulate voltage within this range. E.g. If input voltage varies from 180V to 250V, choose a stabiliser which can correct this.

Voltage Fluctuations
Voltage Drop/Sag
Voltage Surge/Spike
Voltage transient
Electrical noise

Voltage sag or voltage dip, is a brief and temporary decrease of the voltage RMS below a specific threshold (± 10% variation) at an electrical supply line point. It can be caused by various factors such as sudden changes in load demand by switching large motors or a fault in the electrical grid or power distribution system.

Voltage sag can lead to catastrophic failure of electronic machines and components like semiconductors, controllers, PLCs, Variable Speed Drives, robots, CNC machines and all types of modern electronic circuits.

Voltage sag is regarded as one of the most harmful power quality disturbances due to its costly impact on sensitive loads. The vast majority of the problems occurring across the utility, transmission and industrial sides are voltage sags.

Voltage sags cause power quality issues in many industries, however, they are the most problematic in the semiconductor industry. They cause loads to de-energize and hinder production cycles. The impact? Losses in millions of dollars.

In the manufacturing industry, even a brief voltage sag can result in significant losses. For instance, a momentary voltage dip can trip a fourdrinier machine which can alter the intended paper thickness and turn into rejection.

Voltage surge is a short term increase in voltage that lasts for milliseconds or microseconds. It can be caused by lightning strikes,power grid switching or sudden electrical load changes.

Voltage spike is a very brief and sudden increase in voltage that typically lasts for nanoseconds. It can be caused by switching on inductive load (E.g. Motors). They are generally of shorter duration and higher magnitude than voltage surges.

Both Voltage surge and Voltage spike can cause failure of electronic devices if not controlled properly.

Transient voltage is a temporary unwanted voltage in an electrical circuit that ranges from a few volts to several thousand volts and lasts microseconds up to a few milliseconds. It can be caused by arcing , lightning strikes or multiple on and off of capacitor banks and generators.

Voltage transients can harm electronic devices.

Noise is an unwanted high-frequency disturbance or interference with the electrical signal. Noise can come from within the system itself where it is caused by faults in the switchgear and the wider electrical design, or from an outside source.

Electronic noise harms sensitive electronic equipment like micro processors.

Electronic components worldwide are designed to perform optimally as long as supplied voltage confirms to ITIC curve 2000 (Information Technology Industry Council) any power conditioning device which corrects power to confirm to this ITIC curve will ensure long life for electronic gadget that is the minimum requirement of good power conditioning

Yes, because a static voltage regulator takes care of all voltage quality issues, viz: fluctuations, sag, spike, surge, transient and noise. It is a complete Power Quality device which corrects poor power to make it fit for powering modern-day electronic gadgets. Additionally it has a high energy efficiency too.

If you do not have a stable neutral or if the neutral is broken, you can generate a fresh neutral by using an optional Neutral Generation system with a static voltage regulator.

You will necessarily need a UPS where your goal is not only to protect against poor power quality but also to have uninterrupted power in case of a power blackout. For every other application there is Static Voltage Stabiliser