Voltage Regulator "Mark V - MarelliGenerators MJB 160 Instructions Et Avertissements Pour L'installateur

If a locking element has to be replaced, make sure that the new one is of the same type and same resistance class of the original.
The fallowing table indicates the tightening torques valid for locking screws and nuts:
Fixing of electrical connections
Fixing of screws in low strength material components
(aluminium).
Fixing of components (endshields, bearing caps, etc).
Fixing of feet or flange.
5. VOLTAGE REGULATOR "MARK V" ( M16FA655A )
The generators are provided with automatic
voltage regulator (AVR) MARK V.
The AVR is provided with potentiometers to
adapt the characteristics of the AVR to
different operating conditions.
The AVR is provided with adjustable stability
circuitry to allow operations in a wide range of
applications.
The AVR is equipped also with protecting
circuit allowing the generator to operate
underspeed if not loaded.
ATTENTION!: it is not advisable to have the generator operating loaded when the frequency (speed) is below
the rated value: this kind of operation is an overload for the whole generator excitation system.
CONNECTION OF AVR
The AVR is connected to the terminals of the generator and to exciter FAST-ON terminals.
USE OF POTENTIOMETERS
P1/VOLT- Potentiometer for adjusting the output voltage of the generator; it allows a wide range of voltage setting (i.e.
between 350 and 470 V; or between 170 and 260 V depending on winding connections)). When resetting the potentiometer,
the voltage has to be set in the range +5%,-5% around the rated voltage of the machine. In order to obtain a finer
regulation, or to adjust the voltage from control panel or to limit the voltage range, it is possible to insert an external
potentiometer.
⇒ increase voltage
P2/FREQ- Potentiometer for changing the low speed protection. Usually it is set in order to reduce the excitation when the
speed is 10 % below the rated value at 50 Hz. By removing the bridge which is normally shorting the auxilary terminals 60-Hz
of the regulator, the low speed protection acts properly for 60 Hz.
⇒ increase frequency of intervention
P3/STAB- Potentiometer for stability adjust. By rotating it clockwise the stability of the regulator increases,but the response
time becomes longer.
⇒ increase response time, increase stability
P4/AMP- Potentiometer for chancing the overexcitation limit device.
The overexcitation limit device helps to protect the excitation system. This device is delayed to avoid transitory
conditions (in case of overexcitation).
⇒ increase response time, increase stability
In the workshop the potentiometer is set in the way the said limitation comes into operation only under
extreme overexcitation.
Radio interference suppressor
The voltage regulator is internally provided with radio interference suppressor, in order to limit the radio interference from the
generators MJB among levels stated by C.E. standards for industrial areas.
Tightening torques in Nm
Application
18
Thread diameter
M 5 M 6 M 8
2.5 4 8
3 5 12
5 8 22
P1 VOLT
P2 FREQ
P3 STAB
P4
AMP
P
Q
Hz
60
⇒ decrease voltage
⇒ decrease frequency of intervention
⇒ decrease response time, decrease stability
⇒ decrease response time, decrease stability
ENGLISH
M 10 M12
12 20
25 40
45 75
-
+
U
S
0