Page 100 - Offshore Electrical Engineering Manual
P. 100
Parallel Operation 87
+ Bus
Equalizer bus bar
A 1 A 1
Generator
G 2 G
Generator
Field A 2 1 A 2 Field
rheostat rheostat
– Bus
FIGURE 2.6.5
Schematic for two direct current generators operating in parallel.
per minute from grabbing the entire load. The only correct way to run compound
machines in parallel is to connect the series fields in parallel, the paralleling connec-
tions being known as ‘equalisers’ (see Fig. 2.6.5 and Bibliography).
From Fig. 2.6.5, if the load sharing is disturbed and generator 1 starts taking more
than its proper load share, its series field current will increase, and this increased
field current flow will be split between the two generator series field windings via the
equaliser busbar. Thus the two generators are affected in a similar way, preventing
generator 1 from taking extra load.
In order to have a proper division of load from no load to full load, it is required
that the regulation of each generator must be same. The series field resistances should
be inversely proportional to the generator ratings.
