MarelliMotori MEC-20 Manuel Utilisateur page 33

PROBLEM
With the generator on,
with no load, the voltage
at the output terminals is
greater than the nominal
value and cannot be
changed using the VOLT
and VFINE
potentiometers.
With the generator
started and operating off-
grid, the generator
voltage decreases
below the nominal value
as soon as a load is
applied or if the load is
increased (within the
generator's nom. limits).
Generator parallel
operation - incorrect
distribution of reactive
power: with the
generator started and off
the grid, loaded with a
partially reactive load,
the voltage does not
decrease to below the
nominal value of the
machine.
Parallel network
operation (in connection
with M50FA400A board):
incorrect, insufficient or
absent power factor (or
reactive power)
regulation.
963857154_U
POSSIBLE CAUSE
With dip switch 1 - Block A set to OFF,
one or both of regulator terminals U and
V are not connected to the respective
generator phases.
With dip switch 1 - Block A set to ON,
one or more of regulator terminals U, V
and W are not connected to the
respective generator phases.
With 1-phase sensing (only terminals U
and V used), dip switch 1 - Block A is in
the ON position.
Regulator failure.
LED lit: overexcitation limitation is active
even if the load applied is lower than the
nominal load.
to
Droop function active: dip switch 2 -
Block A is in the ON position.
Regulator failure.
Droop function not active: dip switch 2 -
Block A is in the OFF position.
Droop function not set: dip switch 2 -
Block A is in the ON position but the PAR
potentiometer is in the MIN posit.
The measurement current transformer
(CT) linked to terminals A and B is
backwards.
The measurement current transformer
(CT) linked to terminals A and B is short-
circuited or not connected.
Voltage and current sensing incorrect.
Sensing is correct if:
❖
Voltage: phases U and V are
connected to regulator terminals U and
V;
❖
Current:
transformer is on phase W.
Regulator failure.
Incorrect selection of the analogue input:
dip switch 4 - Block A is OFF.
No connection
terminals 6 and 8 and the M50FA400A
power factor regulator.
Connections to terminal 6 and 8 are
reversed.
Regulator failure.
measurem. current
between regulator
OPERATION
Check connections
diagram provided with the generator).
Check connections
diagram provided with the generator).
Set dip switch 1 - BLOCK A to OFF.
Replace the regulator.
Perform the correct
limitation set-up, according
instructions in the Regulator Set-up
paragraph in this User Manual.
Set dip switch 2 - BLOCK A to OFF.
Replace the regulator.
Set dip switch 2 - BLOCK A to ON.
Perform the correct droop set-up (PAR
potent.), according to the Regulator Set-
up paragraph in this User Manual.
Reverse the CT conductors on terminals
A and B.
Check connections
diagram provided with the generator).
Check connections
diagram provided with the generator).
Replace the regulator.
Set dip switch 4 - Block A to ON.
Check connections
diagram provided with the generator).
Check connections
diagram provided with the generator).
Replace the regulator.
(ref. connection
(ref. connection
overexcitation
to the
(ref. connection
(ref. connection
(ref. connection
(ref. connection
33