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an investigation of dual stator winding induction machines

an investigation of dual stator winding induction machines

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esist<strong>an</strong>ce for two phase <strong>winding</strong>s. The expression for per phase <strong>stator</strong> resist<strong>an</strong>ce is given<br />

as:<br />

r<br />

1<br />

2<br />

V<br />

dc<br />

s = (11.1)<br />

I dc<br />

To reduce the r<strong>an</strong>dom error during the test, the same test was taken three times <strong>an</strong>d<br />

the average value is used as the <strong>stator</strong> resist<strong>an</strong>ce.<br />

11.2.2 Open Circuit Test<br />

In the open circuit test, three-phase bal<strong>an</strong>ce voltages are supplied to the three phase<br />

<strong>induction</strong> machine <strong>an</strong>d the machine is running without <strong>an</strong>y load. Thus, the rotor speed is<br />

close to the synchronous speed so that the slip <strong>of</strong> the <strong>induction</strong> machine is very small<br />

( ≈ 0)<br />

s <strong>an</strong>d the rotor current c<strong>an</strong> be assumed to be zero. From equivalent circuit view <strong>of</strong><br />

r point, ≈ ∞ when S ≈ 0 , The modified equivalent circuit for open circuit test is given<br />

S<br />

in Figure 11.2.<br />

If the equivalent imped<strong>an</strong>ce for the open circuit test is assumed as:<br />

V<br />

= jX<br />

(11.2)<br />

o Z o = Ro<br />

+<br />

Io<br />

V ph<br />

rs<br />

o<br />

Lls<br />

I ph<br />

Rc<br />

Figure 11.2 Per phase equivalent circuit <strong>of</strong> <strong>an</strong> <strong>induction</strong> machine for the open circuit test<br />

-<br />

423<br />

Lm<br />

'<br />

Llr

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