Pmg Exitation; Special Safety Recommendation; Introduction; Installation - Sincro SK225 SM Manuel D'utilisation Et De Maintenance

8. PMG EXCITATION

8.1 Special safety recommendation

High voltage
The PMG will induce high voltage whan the rotational
speed is on certain level no matter if the altrnator
excitation system is disconnected. During PMG set-
up, prevent touching all voltage parts without protective
insulation.
This symbol signals risk conditions or
haz ard ous procedures that COULD cause
severe injury or death.
WARNING!
High temperatures
PMG during operation can reach high temperatures.
Avoid contact before checking the temperatures level
of PMG. Always wear protective gloves when working
with PMG.
This symbol signals risk conditions or
haz ard ous procedures that COULD cause
severe injury or death.
WARNING!
Magnetic fields
There is a magnetic field presence in the area
sorrounding PMG, even it is not under rotation. Ensure
that devices that can be influenced by (e.g. credit
cards, watches, ...) presence in magnetic field, are
removed from the area. The magnetic field from PMG
may influence on the operation of some medicine
device (pacemakers, ...). Therefore, personnel with this
devices should avoid presence close to the PMG.
This symbol signals risk conditions or
haz ard ous procedures that COULD cause
severe injury or death.
WARNING!

8.2 Introduction

The PMG (Permanent Magnet Generator) can be part
of excitation system on SK225 and SK250 alternator
series. It is used as an independent power supply for
Automatic Voltage Regulator (AVR). Mechanically is
fitted to the NDE side of the alternator. It has permanent
magnets on the rotor. Rotor is fixed on the main
alternator shaft-end while stator is fixed to the alternator
end shield.
Following scheme shows the basic principle of alternator
electrical system that is equipped with PMG.
30
The alternators equipped with PMG might benefit in
following areas:
easier voltage build up;
•
higher sustained short circuit currents;
•
• better performances in case of unbalanced loads

8.3 Installation

8.3.1 Dismounting the PMG
• Remove the NDE end-shield protective cover
Carefully disconnect the 3 poles connector that
•
connects the PMG stator cables with cables that
are connected to the AVR
Unscrew the 4 screws that fix PMG stator to the
•
alternator end shield
Using both hands and appropriate strength, remove
•
carefully stator PMG from rotor PMG
Pay special attention on the fact that stator is
•
attracted with rotor permanent magnets
• After stator is removed it is recommended to protect
the PMG rotor surface with a cloth or nylon due to
the rotor magnetic forces.
• Unscrew 3 screws that holds rotor PMG to the shaft
• Remove the PMG from the shaft
Pay special attention of storage of the rotor PMG
•
due to the strong magnetic forces which may cause
damage or injuries

8.3.2 Mounting the PMG

The procedure should be the same as during
dismounting (point 8.2.1) only in reverse order.
Pay special attention that:
• rotor of PMG is perfectly fit in the shaft seat to avoid
mechanical rubbing between rotor and stator of
PMG
electrical connector of stator PMG is in good order
•
and that connection of male/female side is done
correctly
The Soga S.p.A. techinical office is always available for
any clarification.