Which turbine trip signals provide an immediate main generator trip signal, bypassing the normal 30 sec time delay between the turbine trip and main generator trip?
condenser vacuum low or thrust bearing wear
The function of the generator core monitor is to:
detect small particles resulting from the thermal decomposition of organic materials
The function of the slip rings and brush gear on the collector end of the main generator is to transfer:
DC current from the outlet of the silicon diode rectifiers, through connection bars to the rotor field windings
The voltage regulator controls the main generator field in automatic AC by varying ___ and maintains the ___.
field current to the alternator exciter, main generator terminal voltage when not connected to the grid
What is the correct sequence for shutting down the main generator?
trip turbine, ensure turbine stop valve closed, ensure generator output decreases to below 0 MWe, open generator output breakers
The voltage regulator controls the main generator field by ___.
varying the field current to the alternator exciter
The ___ output is carried via slip rings and brushes to the generator field windings.
silicon diode rectifier
Which of the following turbine trips will result in a 30 second time delay prior to an automatic trip of the main generator?
bearing oil pressure low
How are the main generator alternator exciter windings cooled?
cooling air is circulated by fans on each end of the exciter field rotor through an air-to-water HX in the alternator frame
During plant start up after bringing the turbine up to synchronous speed (1800 rpm), closing the exciter field breaker results in _____.
automatically flashing the exciter field
Why is hydrogen used to cool the main generator?
low density giving it excellent heat transfer properties
