Alstom MX3EG1A - 3. OPERATION; 3.1 Parallel sequence start; 3.2 Voltage regulator

pag. 7
MDE/A133 2295 001
MX3EG1A
2. GENERAL
CHARACTERISTI
CS
The device features a mechanical casing that is 4
U in height and
as wide as to allow up
to 4 pieces to be accommodated in a 19"
rack in addition
to normal flush-mounting.
The casing is
made of hot-galvanized PVC-coated plate frame
inside which the movable part that carries all the electronic
circuits and the local interface slides on guides. The pull-out
action is facilitated by speci
al
'handles', which, when the dev
ice
is "plugged in", are also used to
lock the two parts. The aluminium
frame of the moving part renders the latter excellentl
y rigid.
The device/system interface terminal blocks are located
on the
rear side of the casing
and, for each electr
ical connection, a
screw clamp is available to receive up to 2 cable terminals, 4mm
2
i
in size; using a
special accessory that is included in the supply,
the connection can also be made by means of
Faston units.
Special error
-sensing codes avoi
d inserting relays oth
er
than
those compatible with the housing.
A
cover lid classes the terminal block withi
n the IP20 protection.
When the movable part is pulled out,
the voltage and auxiliary
circuits are
disconnected
.
The device front bears two labels:
one plate listing the factory settings of the device, namely auxiliary
voltage and frequency;
the other plate, always in accordance with the factory settings,
provides a description of LED
signals.
Both these plates can be easily replaced with new ones, showing
all the information as required by the client.
As far as the
factory settings relevant to output relays, LEDs,
digital inputs and relative sett
ings are concerned, refer to tables
A, B and C.
3. OPERATION
3.1
Parallel
sequence start
Upon enabling the digita
l input associated with LB star
t
(with
enabling characteris
tic on front) th
e stability timer td is
started to
allow any external settings to be made;
when the td time is over,
the device begins the parallel sequence.
The sequence can be stopped by enabling the digital input
associated with
STOP, An EXT 1 or An EXT 2 (respective
ly, for
manual sequence interruption or
external failures).
In this case, the command relative to the synchronization
sequence interrupted by
STOP or
an external event EXT1
or
EXT2 as well as any signal correspond
ing to the event are sent;
the partial and total counter corresponding to the mentioned event
is incremented and the event logging is enabled.
Once the parallel has been performed, the sequen
ce is interrupted
when the signal of
"closed breaker" is received (enabling of the
digital input associated with CH52).
3.2 Voltage regulator
3.2.1 Max.
deviation
bar voltage/rated
voltage
The device works
by comparing the Ub bar
voltage with
the Ubn
bar rated voltage.
When the deviation betwe
en the voltages exceeds the
DUb set
value, the 'START request failed' command - due to Ub out-of-
tolerance condition - as well as
any signal corresponding to the
event are sent;
the partial and to
tal counter
relative to the e
vent
is incremented and the event logging is enabled.
3.2.2 Min. generator voltage
The device works by comparing the Ug generator voltage with the
Ugn generator rated voltage.
When the Ug
voltage falls below the DUg set value, the
'START
request failed' command - due to Ug out-of-tolerance conditio
n -
as well as any signal corresponding to the event are sent; the
partial and total counter relative to the mentioned event is
incremented and the event logging is enabled.
3.2.3 Max. voltage difference
The device works by comparing the Ub bar voltage with the Ug
generator voltage.
When the difference between the modules of the two voltages
modules expressed in Ubn and Ugn multiples, exceeds the DU
set value, the 'voltage increase'
(if Ug<Ub) or 'voltage decrease'
(if Ug>Ub) command is sent.
The voltage increase/decrease commands can be of
'continuous'
or 'pulse' type depending on the
regulation mode
that has been
set, that is CPU CONT or PULSE.
If the PULSE mode has been set, the pulse time is de
fined by the
tupu set parameter; the min. pulse interval is
given by the tupa set
parameter.
The device makes it possible
to obtain Ubn and Ugn values that
are different from each other. This allows the parallel to be
performed even
with one
TV
installed upstream and
the other
installed downstream a transformer with Yd group; this is made
by using, on one side, a phase-phase voltage and, on the other,
the
corresponding neutral-phase voltage without the application
of any TV
adapter.