1
\$\begingroup\$

One of the questions in my book goes like this... 'A shunt generator delivers 450 Amps at 230 volts...'. The resistance of the shunt field, armature and brush contacts are given. I get that the 450 Amps is the current passing through the load. But how can the voltage(230 volts) be constant? Though we can make the current in a dc generator nearly constant and unidirectional, but the value of the voltage always remains alternating, isn't it?

\$\endgroup\$

2 Answers 2

1
\$\begingroup\$

Almost in every generator the quantity that's regulated at the output is always voltage, so if you change the load, the current will change but the voltage remains same(or it's supposed to remain same, ideally), and when you say it's a DC generator the the output voltage is Direct, not Alternating.

If you're confused as to how a rotating machine produce a unidirectional and almost constant voltage, it's because of the shape of the poles, they are arranged so that the field on the armature windings remains almost constant-in magnitude and direction as well- but there's one more problem, when armature winding goes from beneath of one pole to another, the voltage suddenly changes direction at the terminals of the armature(magnitude still remains same), but that's one of the reason why commutators are used, to prevent the polarity reversal- and also to deliver power out of the rotating structure.

\$\endgroup\$
0
\$\begingroup\$

Commutator behaves as a mechanical inverter/rectifier in conventional DC machine working as motor/generator.Armature winding always carry AC current. When machine is operated as generator the internal produced AC voltage in armature windings is rectified at commutator to give DC output. When machine is operated as motor, the DC electrical input will be converted to AC in windings.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.