Synchronous Generator

Synchronous Generator - Mecc Alte Alternator

Why Mecc Alte believes that the PMG or permanent magnet generator SYSTEM is OBSOLETE.


The PMG (permanent magnet generator) system, as is true of brushless designs in general, uses a small alternator with permanent magnets, located at the backend of the main alternator, to stimulate operation in the main unit. On the other hand, the Mecc Alte employs an auxiliary winding within its main alternator for this purpose, a simpler, more elegant design (no secondary alternator required), lighter in weight and superior in its performance.




The ADVANTAGES in weight and size of the MECC ALTE auxiliary WINDING.


We already explained that an auxiliary-winding equipped Mecc Alte synchronous generator is lighter in weight and more compact than the standard brushless alternator with PMG system. The auxiliary winding, in fact, is so limited in weight that it barely affects the weight of the main alternator - while having absolutely no effect on the main alternator's dimensions. The PMG setup, by requiring a second smaller alternator as the power supply for its main unit, can have a significant impact on machine weight (depending on the size of the main alternator involved - the larger this primary alternator, the bigger and heavier the secondary or stimulating alternator must be) - and, perhaps more significant, a second alternator means an unavoidable overall length increase to the machine.



Impact of DISTORTED loads and POWER transitions on the auxiliary winding.


It is accurate that the voltage output of an auxiliary winding will be affected slightly by distorted loads and power transitions - when, by comparison, the PMG system is not. The degree of this effect is not only slight, it can be completely compensated for with the design of the electronic voltage regulator (AVR). This means, from the vantagepoint of the end user, that there should be NO material difference in output voltage between the auxiliary winding and PMG systems when load distortions or power transitions occur. When it comes to absorbing power transitions and load distortions, tireless testing of the Mecc Alte synchronous generator has demonstrated that its capacity is absolutely equal to that of a PMG-outfitted unit.



Your PMG system will provide LIMITED transient powered compared with the AUXILIARY-winding synchronous generator.


Because the PMG system has limits related to transient or transitional power, it also is limited in motor-starting ability. The same cannot be said of an auxiliary winding-equipped generator. This difference in motor-starting may not become tangible until an electric motor requires either extremely large currents or more current than was advertised for its activation, but, for someone powering an application, it can be of comfort to know that it exists. It is elimination of the PMG that provides the auxiliary-winding synchronous generator with such unlimited motor-starting potential. In a standard PMG system, the size of the PMG itself dictates motor starting capacity, whereas the auxiliary-winding system is limited only by the machine's motor or power source.




How do SHORT CIRCUITS affect the AUXILIARY-winding system?


The PMG and auxiliary-winding systems are both able to compensate for a short-circuit within the primary alternator (main stator) - by maintaining the proper supply of power to the electronic regulator. If a short occurs in either system, sensing of voltage at the electronic regulator becomes zero, and thus the short circuit current is guaranteed to be greater than 3 times the nominal current. The Mecc Alte synchronous generator system with auxiliary winding can, however, provide higher short circuit current values without impacting alternator weight or size, or the unit's cost, something NOT possible with the permanent magnet generator system.