How does increase in VAR cause increases in bearing damage caused by shaft vibration in the shaft connecting turbine to generator in a 210 MW turbine-generator set?

Another answer which was given to this question is now in the Discussion Area. It gives advice about running small domestic motor-generator sets but does not address the actual question here which is about the kind of turbine-alternator set used in a major power station capable of generating up to 210 MegaWatts of power. Because of the highly technical details given in the question it is clear that it is probably from an exam in electrical engineering and not one on electrical wiring. The full answer to this question would take a chapter in a heavy book about the design of turbine-alternator sets, the kind usually held in an engineering/technical library! Whilst the student should really use his recommended course materials, for those who may be interested this may be a possible part-answer: : VAR means "VoltAmps Reactive". : In the ideal world there would only be purely resistive loads so that there would be no large currents out of phase with the generated voltage taken by loads having high power factors. : Such out of phase currents can easily lead to shaft vibrations between the alternator and the turbine and, if no steps are taken to improve the power factors of the loads which are causing the problem, such vibrations could quickly wreck the turbine/alternator shaft's bearings. : Real-world alternators have to handle out of phase currents but, for the reason implied by this exam question, such currents must always be minimized. : Electric power utility companies always monitor their output for the appearance of any new heavy out of phase current loads. If they see any they take strong action to enforce their supply contract terms to make the consumers who are responsible disconnect their damaging loads until the appropriate power factor correction equipment has been installed. To view or take part in the Discussion click on the View Discussion button below. <><><> Important Note: To find out how it should be done in a safe and legal manner, before you try to connect a generator to your Home Electricity circuits you would be very wise to read the answer to the Related Question shown below: "How would you connect a generator when the power is off?". : ALWAYS CHECK WITH YOUR LOCAL WIRING SAFETY OFFICE BEFORE YOU ATTEMPT TO CHANGE ANYTHING : - ELECTRICAL SERVICE PANEL, BREAKERS, CABLES OR OUTLETS - : ON ANY ELECTRICAL POWER CIRCUITS : IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB

SAFELY AND COMPETENTLY

REFER THIS WORK TO QUALIFIED PROFESSIONALS. If you do this work yourself, always turn off the power

at the breaker box/fuse panel BEFORE you attempt to do any work AND

always use an electrician's test meter having metal-tipped probes

(not a simple proximity voltage indicator)

to insure the circuit is, in fact, de-energized. .