Automatic Voltage Stabilisers

Automatic Voltage Stabilisers (AVS) providea constant source of voltage and current to their connected load by stabilising the incoming AC (alternating current) mains power voltage. The voltage stabiliser has a wide input voltage inside which it can operate to deliver a regulated output voltage. Voltage stabilisers do not change the incoming mains power supply frequency and do not provide battery back-up if a power outage occurs. Other terms used include Automatic Voltage Regulators (AVRs) and Digital Voltage Regulators (DVRs).

Voltage Stabilisation

The principle purpose of a voltage stabiliser is to protect its load from mains present power problems including sags, surges and brownouts. The voltage stabiliser will normally have some form of spike and electrical noise filtering built into its circuits and some form of local lighting strike protection. Voltage stabilisers vary in their type of which there are two principle formats: electro-mechanical and electronic and their input voltage windows.

Electro-Mechanical and Solid State Electronic Technologies

Electro-mechanical or server-assisted voltage stabilisers have moving parts that adjust to the input voltage window and change this to generate a higher or lower output AC voltage. The principle component will be a toroidal core or column electro-magnetic component with rollers that move to adjust the voltage.

Electronic voltage stabilisers are solid state with no moving parts. Solid state voltage stabilisers can react quicker to mains power fluctuations and supply a more closely regulated output voltage. The standard case is typically IP20 with higher IP-ratings available. Other options can include galvanic isolation, harmonic filters and greater lightning protection options.

Maintenance and Remote Monitoring

Due to the moving parts, electro-mechanical voltage stabilisers require periodic inspection (one a year preventative maintenance) to check that the moving parts are free to move and there is no erosion or build-up of materials on the toroidal or column parts.

Voltage stabilisers provide front panel indicators and/or an LCD to provide quick access to information. Remote monitoring may be possible via an optional monitoring card to connect to a local network or via a GSM mobile sim.

Input Voltage Windows

Voltage stabiliser windows vary. The standard input voltage range is typically +/-15% with options for wider input voltages including: +/-20%, +/-25%, +/-30%, +15/-25%, +15/-35%, +15/-45%. The lower the voltage the greater the current drawn to deliver the output power.

Voltage stabilisers can be used for a wide variety of applications requiring from 1kVA to 4MVA of power with single and three phase options. Voltage stabilisers tend to be unity power factor rated (1kVA=1kW) but care should be taken when comparing models from different manufacturers.

Power Conditioning

Voltage stabilisers condition the mains power supply before it reaches the connected loads. Another type of stabiliser is known as a Constant Voltage Transformer (CVT) power conditioner. This device is based around a type of transformer offering galvanic isolation as standard. A CVT has a Mean Time Between Failure (MTBF) of over 200,000 hours (20 years or more) but it is generally limited by its weight and size to single phase applications up to 15kW.

Typical Applications

Voltage stabilisers are widely used in applications requiring a stable AC power source. Typical examples include utilities, hospitals, retail, manufacturing, process control and industrial sites where the mains power voltage can vary or suffer from brownout conditions (low voltages) due to the heavy inductive loads on site.

Other applications include the protection of critical power systems in areas of the world with a less stable mains power supply.

A voltage stabiliser can also be used to widen to the input voltage range of an uninterruptible power supply.

Voltage Stabiliser Projects

Synchronised Power has a wealth of experience in the field of voltage stabilisation and works with several manufacturers. For more information please contact us. We also provide voltage stabiliser inspection and maintenance services.