DC motor speed control
DC motor speed control
(OP)
Hi
I need to replace an old DC drive. The machine is a wire drawing machine. The drives works in speed control. Actual speed input comes from a tachometer mounted at the end of motor shaft. Set speed value is set manually with a potentiometer and there is another potentiometer signal coming from a "dancer" that is moved by the wire drawn by the machine. This dancer is used to syncronize one motor with the next
All 3 inputs are processed in a separeted board (I mean separeted from the SCR converter) and then an output signal from this board goes to the converter to control the firing angule of the SCRs.
Questions:
What is the function of this board?
A Modern DC drive have this board or microprocessor inside?
Can I replace the converter and control board with a modern DC drive?
Thanks!
I need to replace an old DC drive. The machine is a wire drawing machine. The drives works in speed control. Actual speed input comes from a tachometer mounted at the end of motor shaft. Set speed value is set manually with a potentiometer and there is another potentiometer signal coming from a "dancer" that is moved by the wire drawn by the machine. This dancer is used to syncronize one motor with the next
All 3 inputs are processed in a separeted board (I mean separeted from the SCR converter) and then an output signal from this board goes to the converter to control the firing angule of the SCRs.
Questions:
What is the function of this board?
A Modern DC drive have this board or microprocessor inside?
Can I replace the converter and control board with a modern DC drive?
Thanks!





RE: DC motor speed control
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: DC motor speed control
RE: DC motor speed control
Their 6RA70xxxx works also.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: DC motor speed control
In fact just before I wrote the first post a local Siemens representative visit our plant. But he could not answered my question. He is "going to check". He told me they have very low experience with DC Drives
Can you explain me some more about how this speed control works and what is this "free funtion blocks" that you mentined?
Thanks!
RE: DC motor speed control
Short description: There are logic and analogue function blocks that you select and connect using binectors or connectors. Very easy once you start using them. I have done several 'transitions' from old drives to modern ones using these drives.
You could (almost) use the diagrams for the existing analogue functions and calculate things like time constants, gain, integral part and such things* and then use the data in the function blocks. I would say it can be done in a three-five days, including testing with wire. You have to find someone used to it, though. Or you do it yourself. Depends a lot where you are.
*or estimate them from recorded step responses.
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: DC motor speed control
RE: DC motor speed control
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: DC motor speed control
I have being looking the Siemens Catalog and they offer 2 alternatives:
Base Drive Panels: SCR semiconductors and controls + contactor + fuses + trasformer
Power Module Drive: only SCR semiconductors and controls
I think we only need the Power Module because we can use our existing contactors, fuses, etc
Is this correct?
RE: DC motor speed control
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: DC motor speed control
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: DC motor speed control
TMGE makes very versitle digital front ends that will easliy do this application.
RE: DC motor speed control
Each DC motor is 12,6 kW. We want to replace the drives and control card because they are continusly failing