Discussion thread regarding Schematic drawing by ECN's Member "Nick", posted in the Technical Reference Area under the Topic heading:

AC Motor Control Schematic - Per ECN Member

Post your comments and/or questions here regarding Nick's drawing, for him to comment to.

Scott SET. 07/07/2001 07:17:00

edit= embedded hyperlink to schematic

[This message has been edited by Scott35 (edited 10-02-2001).]

I believe this is a Star-Delta reduced voltage motor starter, I have always seen them with a UV relay in the seal in circuit, for added protecction.

Yes, that's exactly what it is. A closed transition wye-delta starter. Could you expand on the under voltage realy?
Nick

There are two general types of low-voltage devices, one of these provides low-voltage release, ie a power failure or a substantial voltage dip interrupts the power flow but does not prevent the reestabliahment of the main circuit when the voltage is restored.
The other is a true undervoltage relay an offers protecction and has to be reset after a power failure.
Timing circuits are often used in this type circuit to help prevent automatic restarting when it is not desired.