my question is this how can i now this PLC will give some (at analog output terminal) gate Signal to the TRIAC or THYRISTOR for change the load voltage so that we can change the speed of motor

[sahilgupta1527 0]

i want to make a project which is like that actually i want to make a speed control  of induction motor using 
Allen bradley micro logix PLC..... for this i place a sensor (temp sensor , air flow sensor, pressure sensor, humidity sensor etc.) 
which give as analog output , now i gives this analog output at  the analog input terminal of AB PLC.. 

my question is this how can i now this PLC will give some (at analog output terminal) gate Signal to the  TRIAC or THYRISTOR
 for change the load voltage so that we can change the speed of motor

[Steve Bailey 118]

I assume you didn't like the suggestions you got when you posted the same question at Phil's site.

http://www.plctalk.net/qanda/showthread.php?t=105098

At least you provided a little more information here about what you're trying to accomplish. If you are trying to control the speed of the motor and the motor is connected to a drive, then the PLC's analog output should be wired to the analog speed command terminal on the drive.

If you are trying to control the armature voltage of a DC motor using a PLC to control triggering of an SCR, a PLC isn't fast enough.

[Armadillo852 25]

2 hours ago, Steve Bailey said:

I assume you didn't like the suggestions you got when you posted the same question at Phil's site.

http://www.plctalk.net/qanda/showthread.php?t=105098

 

I literally laughed out loud when I read this. Not sure why, but I did.

[b_carlton 61]

Typically components to control a motor are packaged in a tested unit called a variable speed drive. These may indeed contain triacs or thyristors. Various configurations and power ratings are available based on the motor type and size you wish to control. Many will accept an analog input as a speed reference. This analog signal can come from a PLC. If you would state the type and power rating of the motor many fine variable speed drives could be suggested.

If, instead, you are asking how to design and build a variable speed drive you may need a different forum.

Edited 4 Sep 2016 by b_carlton