Elektrische spannung und frequenz: variationen

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It is necessary to pay a lot of attention to the electrical voltage (also just called voltage) and the frequency that each electrical device is designed for: 

 110V, 115V, 115-127V or 220V in case of voltage;

 50 Hz or 60 Hz at the frequency. 

It should not be forgotten that countries apply different norms and sometimes – as in the case of Brazil – there are differences in this norm depending on the region. Therefore, the suitability of the device for the place of use should be checked. 

This control is in the border regions – such. B. between Brazil and Uruguay or Paraguay – even more important, since the neighboring countries sometimes apply different standards.

A curiosity related to this variation existing between neighboring countries is the generation of energy in two different frequencies that takes place in Itaipu’s factory. Since it is a factory with Brazil and Paraguay as partners, it was defined that half of the energy generated there should be in 60 Hz (standard in Brazil) and the other half in 50 Hz (frequency in Paraguay). 

However, since Paraguay does not consume all of the energy it is entitled to, part of it is sold to Brazil. For example, the energy generated at 50 Hz has to be converted to 60 Hz in a system in order to be able to be transmitted and distributed to Brazilian consumers.

fluctuations in supply

In the case of voltage, in addition to worrying about the level for which the devices are designed, it is necessary to pay attention to the fluctuations in the supply provided by the electricity providers. In almost all Latin American countries, the voltage varies during peak consumption periods. The same can happen in regions located at the end of the distribution network. 

As a rule, refrigerators withstand fluctuations in the electrical network well. Embraco compressors are designed to work with a voltage deviation of up to 10% more or less than the nominal voltage (which in the case of a 220V compressor means that they work with a voltage between 198V and 242V can).

However, with larger voltage fluctuations, serious problems can arise in the devices, as if they were connected at 220V and only rated for 127V.  

 Voltages above the specified limit for a particular device will cause overload, damage and often burnout. In the case of compressors that are subject to these conditions, the thermal protection usually takes effect. Otherwise the compressor will burn out.

 While burnout is less common in cases where the device is plugged in at a voltage below its specifications, other types of problems can occur. It may just not work and put too much stress on the engine, which can result in damage to parts.

Embraco’s recommendation is to use a voltage stabilizer in cases where the rated voltage is above or below the limit specified for the compressor to avoid this type of problem.

Another recommendation that should be obvious but is sometimes forgotten is to pay attention to the voltage specified for the compressor. In other words, use 115-127V or 220V compressors according to the voltage used at the job site. 

Frequency: Not everything is the same

It is also necessary to pay attention to the frequency for which the compressor is designed. The difference between 50Hz and 60Hz seems small, but using an inappropriate model can cause serious problems. 

In the motors used by Embraco compressors, changing the frequency changes the speed at which the compressor rotates. A simple calculation is enough to see that the frequency of 60 Hz is 20% greater than 50 Hz. This means that if a 50 Hz compressor is rotating at 3,000 rpm, a 60 Hz compressor applied in the same system will be rotating at 3,600 rpm. In other words, a larger capacity is needed that the compressor cannot provide. 

An example that illustrates this difference is a refrigeration system that uses 1¼ HP at 60 Hz and requires a 1½ HP compressor at 50 Hz. 

The main reason for not using a model with an inappropriate frequency is the possibility of compressor burnout, which occurs when the thermal protector does not work. On the other hand, if the thermal protection is too strong, the compressor loses power.

maintain security

In addition, safety is an issue as there is a possibility that the technician and/or user could receive an electric shock. Regarding this issue, it is important to remember certain recommendations from Embraco so that working with compressors is completely safe. 

It is therefore recommended that before connecting a compressor, the technician certifies that the following conditions are met: 

 The voltage indicated on the compressor label must be suitable for the electrical network;

 In single-phase installations, the phase cable must be protected by a circuit breaker and connected to the thermal protector; the neutral wire must be connected to the starting device (relay or PTC); the system must be grounded; 

 In two-phase installations, a two-pole circuit breaker must be used that protects both phases of the power supply in the event of a short circuit. In addition, the system must be grounded. 

The safety manual prepared by Embraco also highlights that using a compressor at the wrong voltage can cause a short circuit in the hermetic terminal area. This can cause the hermetic pins to be expelled and the cooling liquid to leak out. 

When using flammable coolants (e.g. R600a and R290), this situation can lead to the development of flames and the associated risks. 

The same risk of a short circuit in the area of ​​the hermetic terminal, with the same consequences, occurs if a two-pole circuit breaker is not used.

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