GBE Support:

Distribution transformers are among the most widespread on the market. Installed in residential, hospital, metro and industry buildings, they can feed different types of systems that do not require special services.

This category of electric machine often takes the quality/price ratio more into account, without compromising on energy efficiency. In addition to offering high quality transformers, GBE pays a lot of attention to proposing more energy efficient machinery; this results in greater savings and less pollution.

The new European directives actually require improvements that will lead to transformers with a better performance and lower environmental cost. In addition to the standard machinery with traditional grain oriented core, GBE offers transformers with an amorphous core, a technology that allows high performance and low losses to be achieved.

Fields of application: Construction, Industry, Transport, etc.

The transformers for converters are made specifically to power loads where waveforms are not linear and the harmonic content is not negligible. They can be produced with a single secondary (6 – Pulse) or multiple secondary (12, 18 and 24 – Pulse) phases shifted between themselves. The transformers with different secondaries are indispensable when there is a need to reduce the harmonic distortion generated on the power line or in the case where it is required by the system that will be connected.

The construction methods may vary depending on the type of converters to be connected and the electrical parameters required by the customer. In fact, there are many factors and issues to be taken into account, just due to the presence of non-negligible harmonic content in current and voltage. During the design, it is necessary to always take into account the most frequent problems: the machine overheating, given by the temperature increase in the windings caused by some types of harmonics that create localised magnetic fields; the stress on the magnetic iron core, caused by harmonics under voltage which, in addition to overheating, may give rise to saturation phenomena, especially when no decoupling reactor is present in the system. To overcome these problems, in transformers for converters, the secondary side is provided with a greater insulation, as overvoltage’s are higher compared to those present on a line load.

Fields of application: Induction Furnaces, Power Supplies of Large Engines, Installations and Systems that require Power Control.

The elevator is a special transformer designed to increase voltage. It is usually connected immediately after a generator or at the beginning of two lines with different voltages.

Considering the specific application of this type of transformer, during the design phase, GBE takes into account the voltages, with which the machinery will work, so as to be able to offer a customized product, according to need.

Fields of application: Systems with Low Voltage Generators that Distribute in Medium Voltage.

The transformer for photovoltaic systems is the interface between one or more inverters of the photovoltaic panels and the distribution line.

When dealing with plants with multiple inverters, multiple windings are made, by studying the impedances needed according to the system on which the transformer will be installed. Compared to other transformers, those intended for photovoltaic systems require a more resistant structure, since they are subject to a large number of release manoeuvres. To ensure the safety of the LV windings from discharge to ground, the ground connection is not included on the powered side.

Fields of application: Photovoltaic Systems.

The transformer for wind power plants is used as an interface between the wind generators, powered by wind turbines and the distribution line.

This type of transformer can be installed either outside or inside the wind tower. If positioned inside, the transformers can either be installed at the base of the tower or at the top of it.

The installation of the transformer for wind power plants can present different issues that need to be taken into account during the design phase:

• The reduced space and subsequent limited heat exchange
  
• Strong vibrations
  
• Difficulty in assembly and disassembly in towers with smaller dimensions
  
• When dealing with oil transformers, a higher class of insulation must be considered to avoid problems related to the temperature increase, as well as the use of special oils to minimise the risks related to flammability
  
• The wind power sector provides for stricter environmental legislation
  
• E3 environmental class, to ensure proper operation in extreme weather conditions

GBE has E3 certification

Fields of application: Wind Power Plants.

Three-Phase

The transformer for starting motors is designed to work primarily alongside large motors. A key characteristic of this type of transformer is the high current due to absorption of the motor during the start-up process, followed by a period of operation at the nominal current.

While they may be undersized with respect to the nominal motor current, and the transformers to be connected to the motors, it is always necessary to keep in mind the most appropriate dimensions to ensure proper thermal and mechanical operation during start-up.

Fields of application: Installations of Large Pumps, Turbines, etc.

To reduce the in-rush current of the electric motors, especially on the larger ones, reduced voltages are used opposed to the nominal one.

The auto-transformer for motor start-up consists of an auto-transformer that usually occurs with sockets of 75%, 70% and 65% compared to the nominal voltage value. This way, the motor is started at a reduced voltage, to then be connected to the mains and, finally, the transformer is de-energized. The dimensions with respect to the motor to be started are usually smaller, given that it has very brief operating periods (about 30 seconds). As in the case of transformers for start-up, during the design phase, it is necessary to take into account the correct thermal and dynamic dimensioning. If particular applications are required, the client must establish any voltage drop limits on the motor during start-up.

Fields of application: Start-up of large motors with reduced current.

Better known as grounding reactors, they are three-phase machines that are used to create an earthing point in systems where it is not currently present (on all insulated neutral lines).

With this type of transformer, it is possible to assess any faulty currents and they are used in conjunction with Petersen Coil to ensure the correct operation of the line, even in the event of a grounding fault. In some cases, they are provided with a small power auxiliary to provide power to auxiliary power supply circuits.

There are different construction methods for the grounding transformers, because it is always necessary to consider the very low ground impedance, ensuring correct short circuit voltage on the auxiliary winding. Given that the power of the auxiliary is variable, a value that can go from the grounding power up to a lower power of around a hundred times, it is necessary to carefully choose the type of construction to ensure the impedances requested.