Power Quality in Power Systems and Electrical Machines, 2nd Edition

Solution to Application Example 6.8

The induction motor is operated at 60 Hz (natural torque-speed characteristic) [46].

a) 

$\begin{array}{l}{n}_{\mathit{ms}}=1800\mathrm{rpm},{\omega }_{\mathit{ms}}=188.49\mathrm{rad}/\mathrm{s},{\omega }_m=180.1\mathrm{l}\mathrm{rad}/\mathrm{s},\\ s_{\mathit{rat}}=0.044,\left|{\tilde{I}}_s\left(t\right)\left|=49.82\mathrm{A},\right|{\tilde{I}}_r^{\prime }\left(t\right)\right|=47.66\mathrm{A},\\ \left|\tilde{E}\right|=221.75\mathrm{V},\mathrm{and}{\mathrm{T}}_{\mathrm{rat}}=164.31\mathrm{N}\mathrm{m}\text{.}\end{array}$

  (E6.8-1)

b) Due to constant flux control, the (ω_m–T) or the (s–T) characteristic consists of a family of parallel lines as indicated in Fig. E6.8.2.The maximum torque T_max and the slip s_m where the maximum torque occurs are [46]

Figure E6.8.2 (ω_m–T) or (s–T) characteristics for f_rat = 60 Hz (natural characteristic) ...