6
ENGLISH
SIN.NT.015.6 – M40FA640A/A
Issued 04.2010
The analogue input is usually used for the voltage regulator
control by means of the Marelli power factor regulator, for
parallel operation with the grid.
This input can be also connected to external devices not
made by Marelli, for remote control of the generator voltage
or the excitation during parallel operations (voltage
matching and power factor regulation), as long as those
devices were equipped with suitable outputs (insulated
outputs, and voltage range not higher than +/-3Vdc).
WARNING: in the case of parallel with the grid, and voltage
regulator controlled by an external device by means of the
analogue input, pay attention to the analogue input
voltage value after the load rejection.
In this particular case, in order to avoid any dangerous
generator over-voltages, the voltage value between the
terminals 6 and 8 must be reduced to 0Vdc or to any
values leading to a generator voltage not exceeding the
rated + 5%.
STABILITY SETTING
The voltage regulator is provided with internal adjustable
stability circuits in order to allow operation in a wide range
of applications.
The stability of the regulator can be set on field to adapt it
to the characteristics of the plant and/or the driving engine
(diesel engine, water turbine, gas turbine) in order to obtain
the best voltage response.
To change the stability characteristics of the regulator, it is
necessary to act on the potentiometer “STAB” (for fine
setting of stability).
An additional coarse setting of stability can be achieved by
means of the micro-switches number 1 e 2.
DROOP KIT DEVICE
The device is included in the voltage regulator, to allow
parallel operation between similar generators: the device
permits to share correctly the total reactive power required
by the load among all generators operating in parallel.
The device is composed by an external current transformer
(which senses the current in phase “W”) and the internal
“droop” circuit of the regulator. The C.T. is placed on phase
“W”; the phases “U” and “V” have to be connected to
terminals “S1” and “S2”.
The voltage regulator is provided with input terminals
(terminals “A” and “B”) for easy connection to an external
current transformer. Such terminals are normally shorted
by a connection bridge, when the generator is used in
single operation.
If the voltage is increasing as the load increases, it is
necessary to reverse the leads of the current transformer at
the terminals A-B.
