Cramaco G2R 400 Serie Manual De Instrucciones página 10

2.1.7 COUPLING SYSTEM – BEARING
The G2R 400 series has a B2 configuration in which are all the SAE (flywheel and housing) possibilities that usually
require a diesel motors market. Also, by order we can do special couplings.
The bearings used are pre-lubricated and sealed, so won't be needed to put grease for lifetime. Under requirement it
could be supply with lubricated bearing. It is necessary to change the bearing after 20000 hours of use.
2.1.8 VENTILATION
The generators are self ventilated. The fan is on the drive side. The air gets in through the grille over the exciter side
and is pushed through it and the principal generator, to go out by the front grille on the coupling side. The fan is
radial type so, it can rote to both sides.
2.2. PERFORMANCE
2.2.1. VOLTAGE AND TIME OF REGULATION
The static voltage regulation is ±0,5 % in any conditions of power-factor between 0 (over excited) and 1, and not
depend of the generator temperature.
2.2.2. OVERLOAD
The generators are designed to pass the overload norms, but under this conditions is not possible guarantee the
regulation voltage . For starting motor is possible to have an overload of two times the nominal current, for no longer
than 20 seconds.
Add the nominal values of power of a generator, letting the air refrigeration at less temperature than the established,
is just accepted with a previous agreement with the manufacturer.
2.2.3. SHORT-CIRCUIT
If there is a short-circuit in the principal terminals generator, it will have firstly the maximum current of short-circuit.
This tip's value is independent from the excitation system. On the other hand, the permanent short-circuit current,
depends on the excitation system. The excitation system used by generators makes that the permanent short-circuit
current bigger than two times and a half of the nominal value. As maximum time of the short-circuit must take 3
seconds.
2.2.4. PARALLEL OPERATION
All our generators have a damper cage , so that, they can run in parallel with the net or with other
generators. Also, at first, wrong synchronisation must being avoid. They can damage the machine. There is
protections for the rectifier against this fails but is impossible have total security.
If it is request a common neutral to operate with a parallel system, it will need a reactance, which could be leave out
if the voltages on the generator's phases are free of harmonic, or same generator type are used. Also mind the
following considerations:
2.2.4.a)PARALLEL OPERATION WITH THE MAIN
This kind of operations, in order to have a tension drop depending of the reactive load, one stabiliser transformer is
incorporated to the W phase before the outgoing terminal (drawing 19762 and 19769). It has a relation ... /1A and is
connected to a variable resistance which allows the adjustment of this drop (see drawing 19689 for special two
transformer connection, double star 3 × 220 V machines) .
At the moment of parallel running, the correct distribution of the active current depends just on the engine control
activation, on the other hand, reactive load distribution it's a function of the generator's excitation conditions.
This could be modify by variations on the tension adjuster reference, in which the customer can intercalate in the P/Q
leads (voltage regulator AEC 42-7). Obviously when is used a reactive drop of tension, the regulation voltage, is not
valid.
2.2.4.b) PARALLEL OPERATIONS WITH EQUAL GENERATORS
If an equal generator is used in parallel, a distribution of reactive load is obtain through a drop of reactive tension
IMPORTANT
In all cases of parallel run is recommend to do the next procedures:
A) Check the existence and the good running of the inverse power protection.
B) Open the circuit breaker A-B from the AEC 42-7 (lets the reactive drop resistance on) an closed D-N (the
protection for overexcitement is eliminated), previous the first step of put it in parallel, equalise the value of tension
of the generator with the bars using the incorporated potentiometer to the regulator, identify as "VOLTS"
C) Once in load, if the value of power is lesser than the nominal, It should correct by changing the resistance
connected to the terminals A-B
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