Re: Vector Drives
i have never found a book that explains things about vector drives other than the instruction manual that the manufacturer supplies with the drive. this is my own conseption of the vector drive from what i have gathered during their installation...
variable speed drives use a standard motor and control it's operation (speed) by creating a variable speed d.c. frequency. you have speed control, but not "exact speed control"!
a vector drive requires a matching vector drive motor with a feedback signal via a special control cable that creates an "exact speed control"! and as explained above, it can provide 100 per cent torque at zero rpm or a locked rotor effect without damage or heating within the motor.
consider our first install on a vector drive... it was in a large mechanical processing plant. they had a 100 h.p. motor geared to a large reduction gear box with a clutch. this gearbox provided a back and forth motion to a large table that moved about eight feet in each direction through a clutch for engagement. the gear box was about the size of a volkswagon and was supseptable to failure due to the abrupt --load-no load action of the process function! the motor (100 h.p. - 480v - 3 phase) was operating at near full load at all times while operation at 1800 rpm.. this local "garue" of drives was involved in the company's operation and called us to do the installation since we had worked together on many static drive installs. he is 83 years old and is one of the first in this area to introduce drives --- very interesting to work with --- it takes a while to get him to speak about drives where an electrician can understand-- but he can get down to our level!!!
he had us remove the 100 hp motor and the "volkwagon" gear box. he had calculated that a 60 hp static drive could do the same job as the 100 hp unit! we provided and installed the static drive motor shaft via a direct coupling to the mechanism's table gear! he then, programmed the static drive to operate enough turns in one direction to drive the table to it's maximum position in one direction and then he programmed it to stop and turn a programmed number of turns in the opposite direction to drive the table to it's maximum operating position! he started this by the beginning the back and forth motion in each direction, then increasing the stroke until the proper movement was reached! of course we are all standing there waiting for the motor to overheat and trip out!!!! wrong!! the motor never even got warm!!! and the plant only paid for the "actual work" the motor used, which reduced their normal operating costs by near $1000.00 a month!!! i think the installation and material costs for this job was about $36,000.00 and the owner was very happy to pay it considering the power and air conditioning saving and never had a failure in over five yaers that i knew of!!! they usually were required a major overhaul about once a year on the original installation, and it usually was a major breakdown with catistafic(sp) damage. he told us that in some countries, they have used static drives directly geared to elevator cars -- no cables --- thats how reliable and accurate they are!!!! the programming of these drives is the hardest job since they can have thousands of applications!!! and it is the responsibilty of the programmer to set the limitations of the drive to protect it and the drive's function!!! an example would be linking on directly up to a printing press --- you must know and program in the maximum "press speed" to protect the press from "flying apart"!!!! we actually, had one setup on a press, and about six months later found out the owner had found our user code and removed the "maximum speed setpoints" and was running about ten per cent over maximum speed with no maximum setpoint!!! i sent him a letter about it and put him on notice of the consiquence of his actions and explained that he would be responsible for damage to personel and equipment!!
