why is it that the HT motors & motors having very low kW
rating(<1kW) have windings connected in STAR, whereas the
motors having in between kW ratings have DELTA connected
windings??

Answer Posted / avdhesh

The basic differance in star and delta connection is that
in delta connection voltage across the winding is line
voltage (V-line) and in star connection it is phase voltage
(V-line/1.73). Same way current in each winding in delta
connection will be (I-line/1.73) and in star connection it
will be line current(I-line). Now to design any motor one
has to take cost of insulation as well as copper.In delta
connection you need higher insulation and in star
connection you need thick conductor to cary high current.

For HT motors current is less as voltage applied is high
hence to reduce insulation cost star connection is made.

For higher rating LT motors since current is high delta
configuration is recommonded.

If we do not follow above than cost and size of machine
willbe increase.
Hope this is the answer of your question.

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