RJ44
Industrial
- Apr 16, 2006
- 4
Greetings to all. I have just joined up.
Anyone familiar with old Electric Regulator Statohm drives?
Model is 9350-155-103 and motor is 50 HP 500V. Motor is driving a plastic extruder.
There is a very slow oscillation, about 2 Hz, at certain speeds and load currents. The oscillation is in the form of wide swings in RPM, with accompanying swings in current.
With armature feedback, the oscillation occurs at about 500 RPM and below and 15 amps armature current.
With tach feedback, the oscillation is similar but occurs right from start-up with no load (2-3 amps).
The problem dissapears at higher speeds, e.g. 1000 RPM and the drive operates just as it should.
The circuit is a common type, with a current regulator loop inside of a speed regulator loop.
The current and speed stability controls have no effect on this slow oscillation. Neither does the IR comp with armature feedback.
All circuits appear to be operating as they should. I don't believe this is due to a misadjustment of the stability controls. At the problem-free speeds, I can cause and eliminate instability by adjusting these. They seem to be affecting things as they should. This "normal" instability is at about 10 Hz.
Apparantly I am not looking closely enough or in the right place. Any idea what general area of this type regulator circuit this problem could reside in?
Anyone familiar with old Electric Regulator Statohm drives?
Model is 9350-155-103 and motor is 50 HP 500V. Motor is driving a plastic extruder.
There is a very slow oscillation, about 2 Hz, at certain speeds and load currents. The oscillation is in the form of wide swings in RPM, with accompanying swings in current.
With armature feedback, the oscillation occurs at about 500 RPM and below and 15 amps armature current.
With tach feedback, the oscillation is similar but occurs right from start-up with no load (2-3 amps).
The problem dissapears at higher speeds, e.g. 1000 RPM and the drive operates just as it should.
The circuit is a common type, with a current regulator loop inside of a speed regulator loop.
The current and speed stability controls have no effect on this slow oscillation. Neither does the IR comp with armature feedback.
All circuits appear to be operating as they should. I don't believe this is due to a misadjustment of the stability controls. At the problem-free speeds, I can cause and eliminate instability by adjusting these. They seem to be affecting things as they should. This "normal" instability is at about 10 Hz.
Apparantly I am not looking closely enough or in the right place. Any idea what general area of this type regulator circuit this problem could reside in?