MarelliMotori MEC-20 Manuel Utilisateur page 31

NOTE: with this setting, the underfrequency limitation is calibrated so that it operates as soon as the generator
speed decreases to below 90% of the nominal speed, with slope equal to about 2 per-unit (pu).
For a V/f type underfrequency limitation, or with a slope of 1 pu, don't consider points 7 and 9, but only point
8, making sure that after the red LED lights up, FREQ is rotated counter clockwise, far enough to make the LED
go out. The generator voltage must be equal to the rated voltage.
Finally, turn SLOPE completely counter clockwise.
Improvement of response speed / regulation stability
❖
10 Improvement of response speed: turn the STAB potentiometer slightly clockwise, being sure you
don't reach a generator voltage oscillation or overshoot.
❖
Improvement of regulation stability: turn the STAB potentiometer slightly counter clockwise.
11 Apply a load to the generator and check the voltage transient.
Then, release the load and check the voltage transient.
12 Repeat points 10 and 11 until you reach the regulation stability or response speed desired (which is also
obviously related to the type of machine and load given).
Setting the overexcitation limitation
13 Apply a load to the generator that is equal to the machine's nominal load (nominal current and power
factor).
14 Set dip switch 3 - BLOCK A to ON.
15 Turn the AMP potentiometer counter clockwise until the yellow LED lights up.
16 Turn the AMP potentiometer clockwise enough to make the yellow LED go out. The generator voltage
must be equal to the rated voltage of the machine.
17 Set dip switch 3 - BLOCK A to OFF.
18 Release the load.
Setting the Reactive Droop Compensation (Droop) - Only for generator parallel
19 Apply a load that is at least partially reactive to the generator, of known value and power factor (for
example nominal current and power factor).
20 Set dip switch 2 - BLOCK A to ON.
21 Turn the PAR potentiometer clockwise until the generator voltage decreases to the desired value,
depending upon the value and type of load (for example, in the event of nominal current and PF=0.8,
PAR must be turned clockwise until a 4% decrease compared to nominal voltage is obtained).
22 Release the load.
Connection to Marelli Motori M50FA400A Power Factor Regulator
23 In the event of connection to Marelli Motori M50FA400A Power Factor Regulator, set dip switch 4 -
BLOCK A to ON, otherwise leave it in the OFF position.
11. TROUBLESHOOTING AND OPERATIONS
The following table completes the section Troubleshooting and Operations from the Marelli Motori Generator Use
and Maintenance Manual, with specific attention to the aspects concerning the regulation.
It is possible that some of the problems described below can also be attributed to other generator components
and not only to the regulator; it is also possible that certain regulator failures are caused by external problems or
defects, for example, from the machine, the devices connected to it, incorrect use, etc.
For this reason, always consult all available documentation, in particular these User Manual, the generator Use
and Maintenance Manual and the connection diagrams that are normally provided with the generator.
In the event
troubleshooting/problem determination by disconnecting any other devices connected to the
voltage regulator (power factor regulator, overexcitation device, external remote controls,
etc.). In the event that the problem does not occur when only the voltage regulator is
operating, reconnect the auxiliary devices one at a time to identify which one causes the
problem. Then consult the User Manual related to the identified device.
963857154_U
of one of the problems described below, conduct the proper
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