UNIQUE AT HEART
FOR 70 YEARS
Three-phase 3.5-32 kVA
Common regulation of the three phases
Three-phase 3-120 kVA
Independent regulation of each phase
Three-phase 22-800 kVA
Common regulation of the three phases
Extended warranty to 5 years.
The cooling in IP21 models is ensured by natural convection only. The total absence of fans (fan-free) increases the reliability of the product dramatically and makes the use of filters, which would need constant maintenance, unnecessary.
The criteria used to size the electrical and electronic parts guarantee the greatest reliability. The declared performance is always ensured in the worst operating conditions simultaneously and for unlimited time (heavy duty): nominal power with minimum input voltage, highest input current and at the declared ambient temperature.
Single-phase and three-phase voltage stabilisers from 1 kVA up to 8000 kVA.
IREM voltage stabilisers are characterized by long life, no degradation of performance over time and reduced maintenance requirements, thanks to the robustness of construction and the high quality of the materials used.
The whole product range has a very high level of customization, both in terms of electrical characteristics as well as mechanical and aesthetic. A staff of technicians specially dedicated to “special” projects can satisfy the most demanding requests.
SHORT DELIVERY TIMES
The particular architecture of IREM voltage stabilisers allows to satisfy in a short time even the most demanding project, reducing design and production times. Moreover, the modular system used for higher power models simplifies transport and reduces time and cost.
NATURAL AIR CONVECTION
This is the distinctive characteristic of all models with protection degree IP21; it dramatically increases the reliability as the cooling of the magnetic components and the electronic control boards is ensured by natural convection without fans. Fans and the relevant filters must be constantly checked, cleaned and periodically replaced.
Moreover, the absence of fans avoids sucking of dust which would deposit on the copper tracks reducing the contact surface between the electro-graphite rolls and the transformer tracks. As a consequence, this would cause roughness, sparks and copper smelting, phenomena that in the long run would damage the component and reduce its life expectancy.
When the voltage is stable and the contact point is the same for several minutes, temperature can exceed 200°C. To avoid this problem, many manufacturers of voltage stabilisers install fans on the brush holder.
The pictures clearly show that NO fan is used in IREM variable transformers to cool down the contact point between brushes and turns. This is possible thanks to the thermal dissipation being the result of:
- the correct sizing and the high permeability of the magnetic cores;
- the low density of current flowing through the windings of the variable transformers, and consequently the reduced thermal dissipation;
- the square section of the linear variable transformers.
DECLARED POWER ON HEAVY DUTY
The fundamental parameter of a voltage stabiliser is the nominal power; it is expressed in kVA and the relevant number, indicated in the name plate, represents the maximum power that the equipment can deliver.
The power figure must however be contextualized with reference to the service class, to the input voltage fluctuations and to the ambient temperature.
THE SERVICE CLASS.
The standards define different types of service, i.e. operating conditions, for the electric machines. An electric machine may have a different nominal power depending on whether it is designed to operate continuously or with intermittent or occasional partial load.
INPUT VOLTAGE FLUCTUATIONS.
A voltage stabiliser is characterized by the ability to compensate for the fluctuations in the mains voltage and to supply the connected load at a constant voltage and close to the nominal value. The work of the stabiliser is to supply the additive or subtractive compensation voltage which will act as a corrective for the mains voltage. The most heavy working condition is in presence of the minimum mains voltage in input.
THE AMBIENT TEMPERATURE.
Electric machines are characterized by energy losses produced during energy transformation, which occur in the form of heat.
SQUARE SECTION LINEAR VARIABLE TRANSFORMER
The linear variable transformers are the heart of IREM Sterostab voltage regulators.
They are the most extraordinary, particularly sophisticated to manufacture and technically worked out component.
As a matter of fact the mobile contact ensuring the stabilisation is flown by currents of some tens of Ampere.
The square section winding is characterised by a much higher “filling factor” than the typical round section winding. The pictures show in both types of winding the large difference in surface existing between the copper winding and the magnetic sheet core.
The smaller the surface, the smaller the leakage magnetic flux, which means higher efficiency and less heat to be dissipated.
LOW MAGNETIC PERMEABILITY AREA
Copper winding of linear variable transformers
used in STEROSTAB AVRs
Irem linear vt section
Copper winding of traditional
linear variable transformers
Typical linear vt section
A motorised variable transformer supplies a series transformer the voltage -in phase or phase opposition- necessary to bring the mains to the rated value. The three-phase models are available in two versions:
T models which regulate on the average of the three phases and are suitable for balanced lines and a maximum load unbalance between the phases up to 50%;
Y models that, having three separate control circuits, individually regulate each phase and ensure a high precision both in case of an important load unbalance between phases and asymmetrical input voltages.