I'm still grappling with understanding this. In my case, KVAR caps are across the motor leads at the load side of 1M contactor, and stay connected to the line supply throughout transition from wye to delta.
I can see why one wouldn't want to connect KVAR caps in an open transition arrangement...
Yes, the capacitors remains connected to 1M contactor, and to line power, but I don't believe capacitors switching on and off the line is what prompted Siemens concerns about PFC and open transition wye-delta starting.
During the time it takes to drop out 3M wye contactor and seal 2M to...
Perhaps I'm not thinking about this correctly, but isn't this precisely what occurs during open transition?
When first turned on the motor is wired for wye operation when the 1M and 3M (wye shorting) contactor are closed, then, some short time after the motor is at speed, the 3M contactor...
Thanks to all for the excellent feedback. I've been doing a spate of additional reading, and will be mulling over the results.
After reviewing our utility's analysis and recommendation see I've incorrectly assumed MV capacitors to provide an additional 9.6 MVAR would be located in our...
Prologue
Our facility uses a 10 MVA, 69kV:12470V transformer to feed a mixture of 12470:480 transformers (mostly delta-wye, but with one 3750 KVA delta-delta, and a 2500 KVA wye-wye). The utility doesn't charge for low power factor, but we're planning several process line additions, and must...
Out of curiosity, would you happen to have any large DC drives (or some other high power electronics that uses phase angle fired thyristors) on the same AC bus as the drives that are tripping?
I've seen various AC inverter drives that are susceptible to the 'notching' DC drives produce, and...
RSnow, it is as itsmoked and waross said. In your case the difference in pulley size isn't much in either case (problems develop when trying to transfer considerable power with a small pulley on one side, and especially when motor and driven shafts are physically close to one another), but is...
Here is a [url=http://www.vmars.org.uk/capacitor_reforming.htm]decent article on capacitor reforming [/LINK]which should answer many of your questions.
Also, consult the drive manufacturer's documentation, or give their engineering department a call. I know ABB goes into this in one of their...
PNachtwey hit the nail headwise. Even if the PLC in question is capable it isn't worth the effort to roll-your-own.
Certain PLC models have autotuning built in, but you'll likely end up hand-tuning the loop. Don't despair, because there are few better ways to develop an understanding of loop...
2422:43 (is this a planetary gearbox? European manufacturer?) represents a ratio of 56.326:1, and yields these final screw speeds at 60 Hz (actually, a bit lower once slip is factored in).
2 pole, 3600 RPM motor, 63.9 RPM screw
4 pole, 1800 RPM motor, 32.0 RPM screw
6 pole, 1200 RPM motor...
The only answer possible with this level of information is "maybe". It is necessary to consider, among other things, load characteristics, and the present configuration of the DC drive/motor combo.
For instance, does the existing DC motor operate at full field at base speed and below, or does...
crjones, you have me in 100% agreement except for your description of how motor temperature rise works. Insulation class and service factor must be factored in as well as ambient temperature.
Toshiba application note AG-05 is one of the more concise explanations...
Thanks, crjones, your observation about compensating for reductions in the effective open area between the OEM's original design, and our filter modifications makes sense to me.
It isn't difficult to build boxes to effect this surface area increase in the case of the I-R compressors, but there...
We have a mix of I-R and Kaeser air and water cooled rotary screw air compressors. Our plant's ambient air has enough dust (plastics fines, cardboard dust, and, since the equipment room is adjacent to the maintenance department, often influxes of other types of dirt), and in all cases we've...
