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AUTOMATIC

VOLTAGE

STABILISERS

MOTOR

CAPACITORS

LIGHTING

CAPACITORS

AUTOMATIC POWER FACTOR

CORRECTION

STATIC

POWER FACTOR

CORRECTION

FIXED

POWER FACTOR

CORRECTION

POWER FACTOR

CORRECTION

COMPONENTS

POWER

ELECTRONICS

Series

Automatic Voltage Stabilisers

Electrodynamic Stabilizers with Digital Control

DESCRIPTION OF THE UNIT

The stabilising system is designed to operate with rated voltage in accordance with IEC 38 and is expected to be connected between main power supply and load.
The purpose is to supply the loads a stabilised voltage having an input voltage variable with respect to the rated value. The highest input current is obtained with the minimum rated voltage; as the output voltage is stabilised within a close range, the output current is considered to be constant.
Stabilisation takes place on the ‘rms’ value of the voltage and is not affected by harmonic distortion in the mains.
The stabiliser can operate with a load variation range from 0 to 100%; the response time depends on the input voltage percentage variation and on the type of design (indicatively, it can vary between 8 and 24msec/V).
The voltage stabiliser is not affected by the load power factor and since regulation is performed without chopping the voltage sine wave, neither appreciable harmonic distortion nor phase displacement is introduced on the downstream line.
The equipment is housed in a metal enclosure with RAL7035/RAL7032 finish and IP21 protection class. Depending on the type, the stabilisers can be air-cooled (natural or aided convection) or oil-cooled.
When the input variation percentage is –25%, -30% or –45% the unit is provided with a special component (super capacitor) able to adjust automatically the output voltage to the minimum value after a failure in the mains.
Such device prevents from possible damages to the user due to the potentially high voltages that might occur when the rated supply is re-established.

MAINS COMPONENTS

The main components of the stabiliser are:

Buck/boost transformer

The buck/boost transformer is a standard dry-type transformer; the secondary winding is connected in series to the mains while the primary winding is supplied by the voltage regulator.

Voltage regulator

The voltage regulator consists of an autotransformer with continuously variable transformer ratio. The voltage intake varies depending on the contact position; therefore the voltage supplied to the transformer primary winding also varies. The voltage across the regulator contacts (and consequently that on the secondary winding of the buck/boost transformer) is either in phase or in opposition to the supply voltage, and it is therefore added or subtracted to the supply voltage, thus compensating its variations

Auxliary Circuit with Microprocessor

The DSP microprocessor-based control circuit (specific for fully digital drives) compares the output voltage value to the adjusted one. When the percentage variation is too high, the control drives the voltage regulator gearmotor. By doing so the regulator rollers change their position thus varying the voltage drawn and supplied to the buck/boost transformer primary winding.

All the described activities are performed automatically

The voltage stabiliser can operate with input and output voltages different from the rated voltage. Such setting can be performed at the factory or at the Customer's premises by adjusting the dip-switch mounted on the electronic control card within the allowed range and according to the instructions described in the handbook. In the SIRIUS and TAURUS stabilisers, such setting can be performed by communicating directly with the microprocessor from a PC (through an RS232 interface). If the rated output voltage differs from the input voltage, a suitable step-up or stepdown autotransformer should be installed in the equipment. However the voltage stabiliser can work just as well after accepting that the range of input voltage variation is not symmetric.

Importance of Voltage Stabilisers

The correct operation of the majority of electrical and electronic equipment depends on the supply voltage accuracy and stability.

Nowadays, many industrial, commercial and private users are subject to long-lasting fluctuations that can be inconvenient or even dangerous.

More recently, dramatic voltage drops or blackouts have occurred due to low energy production coinciding with high demand. The voltage stabiliser has proved to be an effective device to prevent potential damage caused by input voltage fluctuactions.

Installing a voltage stabiliser is often the solution to ensure continuity and quality of production.

Comparison with a UPS System

The type of utilisation described before pushes towards the choice of a voltage stabiliser instead of a UPS in order to have:

	Lower costs
	High power availability
	Wider input variation ranges
	Overload capacity up to 2In
	Inrush current capacity up to 10In
	Higher reliability and ruggedness
	Absence of batteries and consequent easy storage and handling
	Negligible harmonic distortion because of the use of electronic components only in auxiliary circuits
	Service continuity

Applications

Typical uses include:

	laser cutting machines
	computers
	assemblies with electronic drive
	testing facilities
	food & drink industry
	private homes with installed power (pools, air conditioning units, lifts, etc,.)
	special instrumentation

Use of a Voltage Stabiliser

A typical voltage stabiliser is able to respond to changes in voltage level called sags (voltage drops) and surges (voltage peaks) on the input line.

Sags might be due to undersized distribution lines, connection of large loads to the network, ground faults.

Surges might be generated by disconnection of large loads, increased voltage at the generating plant, atmospheric events.

The duration of such phenomena depends on the cause and is not easily predictable.

Sags are generally more common, especially where the distribution is not wide and efficient.

Other disturbances like spikes, transients, high frequency noise and harmonic distortion have to be treated with the addition of specific filtering systems.

The good functioning of the majority of electrical and electronic equipment depends on the supply voltage correctness and steadiness. Nowadays, many industrial and private users are subject to long-lasting fluctuations that can be inconvenient or even dangerous

Come scegliere uno stabilizzatore di tensione

Generally speaking, a stabiliser can be chosen on the basis of a few elements:

Number of phases

The number of phases depends on the type of load:

One single-phase load: single-phase stabiliser, regardless of the nature of the system where the load is installed.

Combination of several single-phase loads: 3-phase stabiliser with independent regulation on each phase or a single-phase stabiliser on each load.

Three-phase loads: 3-phase stabiliser with independent regulation on each phase or 3-phase stabiliser with regulation averaged across the three phases.

Rated Voltage

Always detect the nominal voltages that are supposed to be present at the input and at the output of the stabiliser. In case of 3-phase systems, provide with the line-to-line voltage value.

Since there are different nominal voltages around the world, do not assume that YOUR nominal voltage is automatically known.

The standard voltage stabiliser can operate with the following rated voltage:

Input variation range

It’s a key information for the choice and the design of the stabiliser.

Establish the nature of the oscillation of the input voltage and always keep a safety margin on such percentage. The standard production can include stabilisers for symmetrical and asymmetrical input variation range. If the input voltage variation goes beyond the rated range, the difference between real and rated variation is transferred onto the output.

Type of regulation

Three-phase voltage regulation can be performed in two different ways:

independently on each phase. Used for 3-phase loads and 1-phase loads with up to 100% unbalance and unbalanced input voltage. In this configuration the voltage stabiliser requires the neutral wire.

averaged on the three phases. Used for 3-phase loads and 2-phase loads with maximum 50% unbalance and balanced input voltage. In this configuration the voltage stabiliser does not require the neutral wire.

Rated Power

Establish the power required to supply your load system and allow for an extra safety margin for possible future extensions.

A voltage stabiliser power is expressed in kVA (kilovoltamperes), whilst load power is often given in kW (kilowatts). The link between these two measuring units is provided by the power factor (cosφ):

kVA = kW/cosφ

Remember that:

kVA = load voltage x load current (single-phase)

kVA = √3 x phase to phase load voltage x load current (three-phase)

If the power factor or the load power in kW cannot be easily established, measure the absorbed currents in order to allow for a correct design of the stabiliser.

All the stabilisers are designed for the maximum input current.

Installation

In order to provide with the best machine, it is recommended to inform about the installation condition. It is necessary to know:

	IP protection degree
	Indoor or outdoor installation
	Installation site altitude and climatic properties
	Ambient temperature
	Possible environmental hazards such aggressive atmosphere, exposure to chemical components and so on.

Advantages

Choosing an electromechanical voltage stabiliser means:

	Smooth and reliable regulation
	Up to ±0.5% output accuracy
	Admitted inrush current up to 10In
	Negligible introduction of harmonic distortion
	High efficiency
	High ratings

MINI AVR

The MINI AVR voltage stabiliser covers the power rating range between 0.3kVA and 150kVA and allows for the choice of several input voltage variation percentages within a broad range (from +30% up to -45%).

For ±15%, ±20%, ±25 and ±30% range the change of stabilisation is obtained through different internal connections.

Fuses or automatic circuit breakers are provided on the regulation circuit to protect against overload and short circuit on the voltage regulator. The auxiliary circuit is protected by fuses.

Where provided, a buzzer is activated whenever an overload condition occurs.

In the lower rating types, a pilot light that indicates when the stabiliser is connected to the mains in mounted on the front. For higher ratings, the stabiliser is provided with a multi-task digital network analyser. Such instrument is able to provide with information regarding the status of the line downstream the voltage stabiliser such as phase and linked voltages, current, power factor, active power, apparent power, reactive power, etc.

The logic control is based on a microprocessor.

MINI AVR Standard Features

Frequency

47/65 Hz

Admitted load variation

from 0 to 100%

Mains waveform distortion increment

<0,2%

Cooling

Natural air - Aided air

Ambient temperature

-15/+45°C

Storage temperature

-25/+60°C

Relative Humidity

95%

Admitted overload

200% 2 min.

Colour

RAL 7032

Protection

IP 21

Installation

Indoor

Rating in relation to the input variation percentage

±15%

±20%

±25%

±30%

-25/+15%

-35/+15%

-45/+15%

0,7

0,5

0,3

0,7

0,5

0,3

2,5

1,5

100

150

100

Any other variation range not mentioned in the table above can be dealt with on request

MINI AVR ±15% Automatic Single-Phase Voltage Stabiliser

Type

Rated

Power

kVA

Input

Voltage

±15%

Max

Input

Current

Output

Voltage

±1%

Rated

Output

Current

Efficiency

Respose

Time

ms/V

Dimensions

LxWxH

Weight

MINI AVR

111-15

230

>94

275x425x260

MINI AVR

113-15

2,5

230

>96

275x425x260

MINI AVR

115-15

230

>97

275x425x260

MINI AVR

117-15

230

>98

300x565x280

MINI AVR

119-15

230

>98

300x565x280

MINI AVR

121-15

230

>98

300x565x280

MINI AVR

123-15

230

102

230

>98

405x670x1150

MINI AVR

125-15

230

128

230

109

>98

405x670x1150

100

MINI AVR

127-15

230

179

230

152

>98

405x670x1150

120

MINI AVR

128-15

230

196

>98

605x850x1450

260

MINI AVR

129-15

230

307

230

261

>98

605x850x1450

300

MINI AVR

131-15

230

384

230

326

>98

605x850x1450

380

MINI AVR

133-15

100

230

511

230

435

>98

605x850x1650

450

MINI AVR

135-15

150

230

767

230

652

>98

605x850x1650

530

MINI AVR ±20% Automatic Single-Phase Voltage Stabiliser

Type

Rated

Power

kVA

Input

Voltage

±20%

Max

Input

Current

Output

Voltage

±1%

Rated

Output

Current

Efficiency

Respose

Time

ms/V

Dimensions

LxWxH

Weight

MINI AVR

111-20

0,7

230

>94

275x425x260

MINI AVR

113-20

230

>96

275x425x260

MINI AVR

115-20