15
2016.06 / h
Electric Power Generation
Installation and maintenance
R450
A.V.R.
4531 en -
i
) Vary the frequency (speed) around 48 or
58 Hz according to the operating frequency,
and check the change in voltage from that
observed previously (~ 15%).
j
) Readjust the speed of the genset to its
rated no-load value.
Adjustments in parallel operation
Before starting work on the alternator, make
sure that the speed droop is identical for all
engines.
k
) Preset for parallel operation (with C.T.
connected to S1, S2)
- Potentiometer
P4
(quadrature droop) in
1/4 position in the case of 5A CT and at 1/2
position in the case of 1A CT.
Apply the rated load (PF = 0.8 inductive).
The voltage should drop by 2 to 3% (400 V).
If it increases, check that neither V and W
nor S1 and S2 have been reversed.
l
) The no-load voltages should be identical
for all the alternators intended to run in
parallel.
- Couple the machines in parallel.
- By adjusting the speed, try to obtain 0 kW
power exchange.
- By altering the voltage setting P1 on one of
the machines, try to cancel (or minimise) the
current circulating between the machines.
- From now on, do not touch the voltage
settings.
m
) Apply the available load (the setting is
only correct if a reactive load is available)
- By altering the speed, match the kW (or
divide the rated power of the units
proportionally)
- By altering the quadrature droop
potentiometer
P4
, match or divide the
currents.
4.2.2 - Max. excitation adjustment
(excitation ceiling)
In standard setting, the potentiometer P3 is
in maximum position.
However, for applications requiring an
overload protection (see 3.2.1.4), the
excitation ceiling must be adjusted by using
the following procedures in AREP and PMG.
Method 1 :
-Connect the AVR to the alternator
-apply load to 110% of rated machine rated
at PF=0.8, the green led is on and the red
one is off.
-record the excitation current value
-adjust P3 until obtaining the red led flashing,
the green one is always on.
-decrease the load to 100% and make sure
that the red led is off.
- Increase the load at 115%, check that the
red LED flashes during 90 seconds and that
the excitation current is brought back to the
above adjusted value (I
ex adjusted
).
Method 2 :
The rated excitation current (see machine
plate) must be multiplied by 1.1 and the
obtained value is used to set the
potentiometer P3 at the right position.
The following table must be used.
Position of P3 I exc (A)
8h
1
9h
1.55
10h
1.95
11h
2.5
12h
3.15
13h
3.65
14h
4.25
15h
4.7
16h
5.15
P3
8H
12H
16H
NB: In the case of a permanent short-circuit,
the excitation current must reach 2.9 x I
ex
adjusted (limited to 9.5A), during 1 second
in AREP or 10 seconds in PMG and shuts
down to a value less than 1A.
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