SINGLE-ENERGY TRANSIENTS.
45
on the point of the wave at which the phenomenon begins, but not
so in their resultant effect,
so in their resultant effect,
21. The conditions with a single-phase short circuit are differ-
ent, since the single-phase armature reaction is pulsating, vary-
ing between zero and double its average value, with double the
machine frequency.
ent, since the single-phase armature reaction is pulsating, vary-
ing between zero and double its average value, with double the
machine frequency.
The slow field transient and its effects are the same as shown in
Fig. 21, A to /).
Fig. 21, A to /).
However, the pulsating armature reaction produces a corre-
sponding pulsation in the field circuit. This pulsation is of double
sponding pulsation in the field circuit. This pulsation is of double
J^^.^-^u^Ji,
Fig, 23. *~ Hymmotrinvl Momentary
Short, Oirmulof Alternator.
frequency, and in not tnuwient, but equally exwtw in the final short-
circuit current*
circuit current*
Furthermore, the armature transient in not constant in its
reaction on the field, but varies with the point of the wave at
which the Hhort circuit HtartH.
reaction on the field, but varies with the point of the wave at
which the Hhort circuit HtartH.
Assume that the Hhort circuit starts at that point of the
wave where the permanent (or rather slowly transient) armature
current should be «ero: then no armature transient exists, and
the armature, current in Hymmetrieal from the beginning, and
shows the rfow transient of the field, an whown in Fig* 23, where A
wave where the permanent (or rather slowly transient) armature
current should be «ero: then no armature transient exists, and
the armature, current in Hymmetrieal from the beginning, and
shows the rfow transient of the field, an whown in Fig* 23, where A