Siemens 1LG0 Installation And Maintenance Manual page 8

Star connection
A star connection is obtained by connecting W2, U2, V2 terminals to each other and
the U1, V1, W1 terminals to the mains.
U1
U2 (V2, W2)
V1
W1
Delta connection
A delta connection is obtained by connecting the end of a phase to the beginning of
the next phase.
U1(W2)
V1(U2)
W1(V2)
Star-delta connection
Star-delta starting allows a peak current reduction. It can be used only when the
reduced starting torque obtained is higher than the resistant torque. Actually, it should
be noted that the torque of an induction squirrel-cage motor is directly proportional
to the square of the voltage. Motors whose rated voltage with delta connection
corresponds to the mains voltage can be started with the star-delta method.
Note:
If the auxiliary or mains cable entries on the terminal box is sealed with gland
plugs, a fl at (standard) screw driver is required for removal.
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