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SINGLE-ENERGY TRANSIENTS. 41

at impressed voltage eo, were short-circuited upon itself, in the
first moment the current in the field would still be i₀, and there-
fore the voltage ao would have to be induced by the decrease of
magnetic flux; and the duration of the field transient, as discussed

in Lecture III, would be TO = — •

7*0

The field current in Fig. 211), of the alternator short-circuit

transient, starts with the value ?V = TWO, and if eo is the e.m.f.
supplied in the field-exciting circuit from a source of constant
voltage supply, as the exciter, to produce the current ?Y, the
voltage cJo' = me® must be acting in the field-exciting circuit; that
is, in addition to the constant exciter voltage <?₀, a voltage (m — l)eo
must be induced in the field circuit by the transient of the mag-
netic flux. As a transient of duration ™ induces the voltage- 60,

to induce the voltage (m — l)co the duration of the transient must
be

where Z/o ** inductance, fo *» total resistance of field-exciting cir-
euit (inclusive of external resistance).

The short-circuit transient of an alternator thus usually is of
shorter duration than the short-circuit transient of its field, the
more so, the greater M., that is, the larger the ratio of momentary
to permanent short-circuit, current.

In Fig. 21 the decrease of the transient is shown greatly exagger-
ated compared with the frequency of the armature currents, and
Fig, 22 shows the curves more nearly in their actual proportions.

The preceding would represent the short-circuit phenomena, if
there wen* no armature transient. However, the armature* cir-
cuit contains inductance also, that in, stores magnetic; energy, and

thereby given rise to a transient, of duration T » *-, where L =

inductance¹, r *» resistance of armature circuit. The armature
transient usually IB very much,shorter in duration than the field
transient,

The* armature currents thus do not instantly assume their
symmetrical alternating values, but if in Kg. 2IB, £/, tV, i/ are
the instantaneous values of the armature currents in the moment
of start, t » 0, three transients are superposed upon these, and



	SINGLE-ENERGY TRANSIENTS. 41 at impressed voltage eo, were short-circuited upon itself, in the first moment the current in the field would still be i₀, and there- fore the voltage ao would have to be induced by the decrease of magnetic flux; and the duration of the field transient, as discussed in Lecture III, would be TO = — • 70 The field current in Fig. 211),* of the alternator short-circuit transient, starts with the value ?V = TWO, and if eo is the e.m.f. supplied in the field-exciting circuit from a source of constant voltage supply, as the exciter, to produce the current ?Y, the voltage cJo' = me® must be acting in the field-exciting circuit; that is, in addition to the constant exciter voltage <?₀, a voltage (m — l)eo must be induced in the field circuit by the transient of the mag- netic flux. As a transient of duration ™ induces the voltage- 60, ^o to induce the voltage (m — l)co the duration of the transient must be

	where Z/o ** inductance, fo » total resistance of field-exciting cir- euit (inclusive of external resistance). The short-circuit transient of an alternator thus usually is of shorter duration than the short-circuit transient of its field, the more so, the greater M., that is, the larger the ratio of momentary to permanent short-circuit, current. In Fig. 21 the decrease of the transient is shown greatly exagger- ated compared with the frequency of the armature currents, and Fig, 22 shows the curves more nearly in their actual proportions. The preceding would represent the short-circuit phenomena, if there wen no armature transient. However, the armature* cir- cuit contains inductance also, that in, stores magnetic; energy, and thereby given rise to a transient, of duration T » -, where L = inductance¹, r » resistance of armature circuit. The armature transient usually IB very much,shorter in duration than the field transient, The* armature currents thus do not instantly assume their symmetrical alternating values, but if in Kg. 2IB, £/, tV, i/ are the instantaneous values of the armature currents in the moment of start, t » 0, three transients are superposed upon these, and