Safety Precautions; Description - MarelliGenerators MJB Serie Manual Del Usuario

SIN. SIN.NT.034.0 – PMG
2.

SAFETY PRECAUTIONS

Before carrying out any kind of assembly operations and use of the PMG generator built by Marelli
Motori, please read carefully and entirely all the instructions contained in this Technical Note and in the
documentation normally supplied with the generator.
WARNING: rotating electrical machines can include dangerous parts for the safety and security of the
person, since live or moving during operation, or because during normal or abnormal operating
conditions they can reach high temperatures, hazardous to humans in the case of direct contact.
Therefore pay great attention as the following:
improper use,
removal of guards and disconnection of protective devices,
lack of inspection and maintenance
can cause serious damage to people or property.
Any mechanical installation and/or wiring of the generator must be carried out by qualified and informed
personnel, when the generator is turned off and when ascertained that a sufficient period of time has
passed for the components to cool down, to a temperature not hazardous for the safety of people. All the
tools required to ensure proper safety conditions must be provided (goggles, protection gloves,
insulated screwdrivers, etc.)..
Marelli Motori disclaims any liability for damage to the generator, plant or persons, or for loss of profit or loss of money, or
systems shut-downs caused by failure to comply with the safety instructions and/or of installation/use directions set forth in this
Technical Note.
3.

DESCRIPTION

The PMG permanent magnet auxiliary exciter (Permanent Magnet Generator) is a device aimed at powering the excitation
system of Marelli Motori generators. It is used in combination with the compatible voltage regulator (Automatic Voltage
Regulator, AVR), built by Marelli Motori. The PMG is mounted coaxially on generators, end bracket, on the opposite side of the
coupling, in order to facilitate installation and maintenance.
MAIN STATOR
The PMG is offered as an option on sizes MJB 225-250-315-355-400-450-500-560-630-710-800.
It is available on request and special version for sizes 160 and 200.
It is also possible to provide it separately for generators that are set for its use.
The PMG auxiliary exciter can be used in all cases where it is preferable to power the voltage regulator (AVR) through an
energy source separated from the windings of the main alternator.
In particular, an excitation system with PMG allows:
not suffering the influence of voltage deformation caused by the load on the generator: even if the waveform of the
alternator voltage is distorted, the PMG supplies the regulator with a not distorted voltage;
reducing conducted radio interference (normally produced by the voltage regulators and emitted through the output
terminals of the main generator, if the power supply is of derived type);
making the regulator independent from conducted external noise: this can be important if the load presents repetitive peaks
of voltage that can eventually damage the regulator on the long-term;
powering with the appropriate voltage the regulator also on generators built for special voltages (either very high or very
low);
supporting the excitation of the generator even in conditions of short-circuit or overload.
SIN.NT.034.0 – PMG
VOLTAGE
DETECTION
MAIN ROTOR
12
AVR
EXCITER
ENGLISH
AVR
SUPPLY
PMG
07-2013