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Self-regulating alternators


MECC ALTE S.p.A. has won success at home, as well as in the foreignmarkets, with its production of synchronous alternators.

Factory in Creazzo

The validity of its products from technical and qualitative view points, has brought about a remarkable increase in the exports to many European and extra-European countries.

Factory in Soave

After-sales service
Mecc Alte S.p.A. offers a professional and efficient after-sales service with very skilled technicians and a network of after-sales centres all over the world
The new series of alternators called ECN is the result of our long experience in this sector and of diligent studies and researches aiming to keep pace with the technological development of an era where technology is the winning card.

Apart from guaranteeing the characteristics of the preceding series, such as assuring a permanent short circuit current above or equal to 3 times the nominal current, the ECN series has also been improved. As far as its mechanical components are concerned, the endbrackets have a new shape to improve ventilation, the coupling to the drive motor is simpler and the terminal boxes are bigger to simplify the connection of the electric cables. As for the electric components, the electronic regulators are always updated to improve their performance and reliability, with the possibility to interchange them with the previous ones.  
All the ECN alternators have a fixed inductor with skewed slots and a rotating inductor fitted with a damper cage (except for the 4-pole ECN 28 alternator). The windings have a 2/3 pitch in order to reduce the harmonic content of voltage.

The entire series is manufactured according to and complies with the most common specifications such as CEI 2-3, IEC 34-1, EN 60034-1, VDE 0530, BS 4999-5000; special versions are available on request to meet specific specifications and regulations.  

The new ECN series has been designed to meet both the ordinary requirements of the industries and yards and the more technological requirements of applications such as telecommunications, cogeneration, army, aeronautics and maritime sector.


The ECN generators are available with a 50/60 Hz frequency, either with 2 poles ranging from 16.5 to 114 KVA or with 4 poles ranging from 15 to 1560 KVA, with a single or double support.

In order to couple them with the drive motor it is possible to choose among a wide range of flanges and couplings.


The robust mechanical structure permits easy access to the connections and components during routine and extraordinary maintenance check-ups.

The materials used for the manufacture of the mechanical structure are the following: Fe P12 steel for the frame, C45 steel for the shaft and cast iron for the endbrackets.

The standard degree of protection is IP21 or IP23; upon the customer's request, other higher degrees of protection, such as IP45, P54, etc. are available.


Insulation is class H standard. High voltage parts are impregnated with tropicalized epoxy resins by dipping, dripping and under vacuum, so that the insulation level is always very good. In the highpower models, the stator windings undergo a further insulation. Special treatments for particular environmental conditions are available on request.


The self-regulation is obtained through an electronic regulator.

The regulator is fed by an auxiliary winding which guarantees an almost constant supply under any possible operating condition of the generator.

The ECN series can be equipped with the new interchangeable U.V.R.6 or S.R.7/2 regulator, ensuring the same performance. The paragraph "REGULATORS" explains the differences between these electronic devices.


The voltage accuracy is ± 1% in static condition with any power factor and with speed variation between -5% and +30% with reference to the rated speed.


The voltage can he regulated by the "VOLT" potentiometer of the electronic regulator.

By connecting a 100 kW ) potentiometer in the proper terminals it is also possible to obtain a remote voltage regulation in a range of 5% of the rated voltage.


At full load and no load, at constant speed. there is a transient voltage variation lower than 15% of the rated voltage. In such conditions, the 3% voltage resetting will occur in 0.2 seconds for powers up to 300 KVA, while for higher powers it will occur in 0.3 seconds. Make reference to the user's manual for more details.


The permissible overloads are of 300% for 20 seconds, of 50% for 2 minutes and of 10% for 1 hour every 6 hours of operation.


ECN alternators can function in parallel among themselves, notwithstanding the type of alternator and/or in parallel with the mains provided that they are equipped with the special device. This device is available upon request for the alternators up to type 37, while the alternators with a higher power are equipped with this as standard equipment. In case of parallel with the mains we offer the P.F.R. 96/1 electronic device which controls the alternator's reactive current and/or power factor of the alternator.


The standard generators comply with the specification VDE 0875, degree "G" and "N" and with the basic safety requirements of the European regulation on electromagnetic compatibility; by applying the European standards EN 50081-1 and EN 50082-1, we comply with the above mentioned regulation.

On request we can supply filters for more restrictive specifications such as VDE 0875, degree "K", MIL 461-462 D, etc..


The U.V.R.6 regulator (Universal Voltage Regulator, sixth generation) and the S.R.7/2 regulator (Simplified Regulator, seventh generation) may be used without distinction in the ECN alternators without affecting their performance.

The two regulators are perfectly identical in performance although they differ in the indications and sensing.


The S.R.7/2 regulator is an advanced electronic regulator of small size and cheap price, even if it is very reliable. This regulator is equipped with a low speed and overload protection with an adjustable intervention threshold, it works at 50/60 Hz, it has an adjustable voltage stability and it offers the possibility for a remote voltage regulation.


The U.V.R.6 is built with the same technology as the S.R.7/2 and aside from having the same performances and characteristics it also includes the following specific functions:

possibility of three-phase as well as single-phase sensing (we suggest to choose this option in case of very unbalanced or non-linear loads);

leds of self-diagnosis which indicate the machine operating conditions instant by instant. By using the optional device called S.P.D.96/A the information gathered may be remote modified and made available; by doing so additional protections and signaling are available.


This device is sensitive to the sudden speed losses of the main engine in case of high torque and this problem occurs especially with overfed diesel engines. The U.F.P-1 device triggers the electronic control UVR6 or SR/7 (they shall be assembled together), thus considerably reducing the times and thus increasing the capacity to reset the engine speed thanks to a voltage/frequency multifunction characteristic of the control.


The S.P.D.96/A "remote protection warning device" is an electronic device that, when combined with the U.V.R.6 voltage regulator, shows how the alternator is working, from a distant location.

It shows the following operating conditions:

Overload: yellow led on

Normal running: green led on.

Low speed: red led on.

When one of the protections has tripped out,

it is possible to control other devices by means of an exchange contact.

Furthermore S.P.D.96/A has an overvoltage and overspeed detector. Each detector is connected to an exchange contact which may be connected to external holding circuits preventing these types of troubles. S.P.D.96/A is equipped with a standard anodised aluminium box (DIN 43700 drilling) allowing an easy fitting to the control panel.


The RBD-1 is an electronic device which spots the presence of anomalies on the rotating diode bridge (open diodes, short circuit, etc.); this accessory is available on request. Said anomalies are indicated by a red led as well as by the commutation of a relay which, through an exchange contact of 2A 250V, allows the user to obtain signals, alarms or shutdowns. Through an external 12 V battery, it is also possible to memorise the said intervention.


The "Power factor regulator" type P.F.R. 96/1 manufactured by MECC ALTE is a piece of electronic equipment that when fitted to our generators type ECN and ECS with AVIR, allows control of the reactive current and/or power factor of machines working in parallel with the main, thus allowing the maximum exploitation of the plants.

P.F.R. 96/1 is housed in a DIN standard aluminium boxallowing easyfitting to the control panel.


Our whole range can be fitted with anti condensation heather of adequate power depending on KVA.

Voltage of such resistances must be specified when ordering.


MECC ALTE generators comply with the main standards of radio suppression.

To comply with even more restrictive standards, upon the customer's request, it is necessary to fit special filters in the generators, which MECC ALTE is able to design and manufacture.



Upon the customer's request it is possible to install one of the following devices as overload protection:

These components (which are included in the standard equipment of the 37-40-43 type generators) are assembled in the heads of the stator windings and they control the max. temperature. When the pre-set temperature is reached, the thermistors emit a signal that can be used by a trigger device (not included) to protect the generator.

Thermal resistors PT1OO
The resistance of this device varies proportionally to the temperature of the winding where it is assembled. If combined with a thermostat (not included) it allows to set the temperature to the desired value at which the whole protection system trips out.
Bimetallic overload protections
These devices have a NC contact that trips immediately when a pre-set temperature is reached. If the temperature decreases, the contact resets automatically.

Environmental conditions for our generators are extremely diversified.
There are some very restrictive standards concerning the protection degree of machines that, in certain circumstances, must be applied.
MECC ALTE studied a protection system to be fitted on the machines to comply with protection degree IP 45 of l.E.C. standards.

lt’s generally know that the speed of the generator must be the synchronous speed. It’s also know that a diesel engine generally performs the best between 1800 and 2500 R.P.M.

Being the synchronous speed for generators 4 pole-50Hz.1500 R.P.M. could be useful to implement a gear box utilising the maximum power from the engine.

MECC ALTE can furnish gear boxes for satisfying such demand.



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