EE Pro for TI-89, 92 Plus
Equations - Motors and Generators
129
Display: Upper Half
Display: Lower Half
Solution -
Use all the equations to compute the solution for this problem. Press
„
to display the input
screen, enter all the known variables and press
„
to solve the equation set. The computed results are
shown in the screen displays above.
-PQYP8CTKCDNGU
-
φ
A9D
4C
A
Ω
4G
A
Ω
4H
A
Ω
4N
AM
Ω
8HU
A8
ω
ω
O
ATU
%QORWVGF4GUWNVU
'C
A8
++H
AO#
+.
A#
8V
A8
31.4 DC Shunt Generator
The first equation in this section expresses the induced armature voltage Ea in terms of the machine constant K, the
mechanical angular frequency
ω
ω
m, and flux
φφ
.
Ea
K
m
= ⋅
⋅
ω φ
Eq. 31.4.1
The second equation defines terminal voltage Vt in terms of the field current IIf, external resistance Re, and field
coil resistance Rf. The third equation computes Vt in terms of load current IL and load resistance Rl. The fourth
equation expresses Vt as the induced emf Ea minus armature IR drop.
Vt
Rf
IIf
=
+
⋅
(
)
Re
Eq. 31.4.2
Vt
IL Rl
=
⋅
Eq. 31.4.3
Vt
Ea
Ra Ia
=
−
⋅
Eq. 31.4.4
The armature current Ia is the sum of the load current IL and field current IIf.
Ia
IL
IIf
=
+
Eq. 31.4.5
The final equation is an alternate form of expression for Ea.
Ea
Ra Ia
Rf
IIf
=
⋅ +
+
⋅
(Re
)
Eq. 31.4.6
Example 31.4 -
Find the machine constant of a shunt generator running at 31 rad/s and producing 125 V with a
1.8 Wb flux.