Klockner Moeller Electric Parts from KlocknerMoeller.net
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All about Motors
Star-delta switching of three-phase motors |
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| Automatic star-delta starters SDAINL |
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| Arrangement and rating of protective devices |
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Method of operation
Pushbutton I energizes timing relay K1, the normally open contact K1/17–18 (instantaneous contact) which applies voltage to star contactor
Q13. Q13 closes and applies voltage to mains contactor Q11 via normally open contact Q13/14–13.
Q11 and Q13 maintain themselves via the normally open contacts Q11/14–13
and Q11/44–43. Q11 applies voltage to motor M1 in star connection.
When the set changeover time has elapsed, K1/17–18 opens the circuit of
Q13 and after 50 ms closes the circuit via K1/17–28 of Q15 . Star contactor Q13 drops out. Delta contactor Q15 closes and switches motor
M1 to full mains voltage. At the same time, normally closed contact Q15/22–21 interrupts the circuit of Q13, thus interlocking against
renewed switching on while the motor is running. The motor cannot start up again unless it has previously been disconnected by pushbutton 0, or
in the event of an overload by the normally closed contact 95–96 of the overload relay F2, or via the normally open contact 13–14 of the
motor-protective circuit-breaker or circuit-breaker.
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