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Search: Posts Made By: DickDV
Forum: LIVE PLC Questions And Answers August 18th, 2018, 06:48 PM
Replies: 17
Views: 831
Posted By DickDV
I agree that using the variator to avoid large...

I agree that using the variator to avoid large mechanical issues is probably wise if you can fix the ratio reliably. I would also set the variator ratio so the motor (assuming a 50hz motor) is at...
Forum: LIVE PLC Questions And Answers August 17th, 2018, 10:07 AM
Replies: 17
Views: 831
Posted By DickDV
To add a bit to jraef's good comments, choose a...

To add a bit to jraef's good comments, choose a new motor with the same hp as original but with more magnetic poles. For example, if original is 1800rpm motor (four poles), choose a 1200rpm motor (6...
Forum: LIVE PLC Questions And Answers July 21st, 2018, 03:13 PM
Replies: 8
Views: 847
Posted By DickDV
Companies making paper machine winders use a lot...

Companies making paper machine winders use a lot of air knives to do flying splices. You might find some expert help there
Forum: LIVE PLC Questions And Answers June 1st, 2018, 11:13 AM
Replies: 2
Views: 523
Posted By DickDV
I assume that 230VAC line to line single phase...

I assume that 230VAC line to line single phase means 230V split phase as in the supply transformer having a 230VAC secondary with the centertap grounded for the neutral.

If that is the case, then...
Forum: LIVE PLC Questions And Answers June 1st, 2018, 10:52 AM
Replies: 3
Views: 555
Posted By DickDV
One problem that can come up with bipolar speed...

One problem that can come up with bipolar speed and direction is that it is hard to get a true zero speed. The slightest offset voltage or even noise can cause the shaft to creep forward or backward....
Forum: LIVE PLC Questions And Answers May 23rd, 2018, 08:57 AM
Replies: 21
Views: 1,777
Posted By DickDV
One late thought on this. Since this is reported...

One late thought on this. Since this is reported to only occur when going from load to no-load, the problem may be caused by the speed loop being tuned up a little too hot. Reducing the P gain or the...
Forum: LIVE PLC Questions And Answers April 30th, 2018, 12:31 PM
Replies: 15
Views: 1,914
Posted By DickDV
jraef, can you give me a reference or two...

jraef, can you give me a reference or two concerning floating delta no longer being "code". That would be an answer to prayer and end a lot of me preaching against it if true.

That stuff almost...
Forum: LIVE PLC Questions And Answers April 30th, 2018, 11:54 AM
Replies: 5
Views: 565
Posted By DickDV
At 20 years old it would definitely be wish to...

At 20 years old it would definitely be wish to start budgeting for a replacement drive and even moreso considering it's Robicon. It's on short time for sure.
Forum: LIVE PLC Questions And Answers April 20th, 2018, 07:43 PM
Replies: 28
Views: 1,593
Posted By DickDV
to dmargineau, 1. Oversizing any brand or model...

to dmargineau,
1. Oversizing any brand or model of VFD is required on multiple motor applications not because of undersized output current specs but because multiple motors in parallel present such...
Forum: LIVE PLC Questions And Answers April 20th, 2018, 07:06 PM
Replies: 15
Views: 1,914
Posted By DickDV
Rather than buy input reactors, buy input 480/460...

Rather than buy input reactors, buy input 480/460 transformers with a 460/277 wye secondary. Arrange the output windings in wye (star) and ground the center of the wye.
You will have no more...
Forum: LIVE PLC Questions And Answers April 20th, 2018, 07:03 PM
Replies: 15
Views: 1,914
Posted By DickDV
Rather than buy input reactors, buy input 480/460...

Rather than buy input reactors, buy input 480/460 transformers with a 460/277 wye secondary. Arrange the output windings in wye (star) and ground the center of the wye.
You will have no more...
Forum: LIVE PLC Questions And Answers April 19th, 2018, 08:01 PM
Replies: 28
Views: 1,593
Posted By DickDV
I don't mean to offend any one but there has been...

I don't mean to offend any one but there has been a lot of nonsense mentioned here with respect to the ABB ACS355. I've used literally 100's of these units from fractional to 20hp and they are rock...
Forum: LIVE PLC Questions And Answers March 8th, 2018, 08:12 PM
Replies: 7
Views: 659
Posted By DickDV
In a perfect world, the DC braking current should...

In a perfect world, the DC braking current should stop flowing as soon as the motor stops spinning. As a practical matter, the timer is usually set maybe a second longer than actual brake time to...
Forum: LIVE PLC Questions And Answers March 8th, 2018, 07:58 PM
Replies: 1
Views: 572
Posted By DickDV
Actually three questions. All can be answered...

Actually three questions. All can be answered "yes". However, you are generally better off doing positioning with a servo. Trying to do it with a VFD is a stretch for the technology. Sure, various...
Forum: LIVE PLC Questions And Answers February 22nd, 2018, 06:46 PM
Replies: 10
Views: 485
Posted By DickDV
I'd vote for the RTD also. Much more accurate and...

I'd vote for the RTD also. Much more accurate and easy to calibrate.
Forum: LIVE PLC Questions And Answers February 22nd, 2018, 06:41 PM
Replies: 10
Views: 704
Posted By DickDV
Full support for jraef's comments on replacing...

Full support for jraef's comments on replacing the DC motor. I would suggest the ABB ACS800 drive as one of the best for serious Sensorless Flux Vector control as needed in this application. It will...
Forum: LIVE PLC Questions And Answers February 17th, 2018, 08:25 PM
Replies: 12
Views: 1,198
Posted By DickDV
I don't mean to suggest this as any kind of...

I don't mean to suggest this as any kind of practical solution but I believe you will find that an AC rated coil in a relay will operate successfully at a much lower DC voltage. You can play around...
Forum: LIVE PLC Questions And Answers February 17th, 2018, 08:04 PM
Replies: 13
Views: 569
Posted By DickDV
A three phase softstarter will not convert single...

A three phase softstarter will not convert single phase to three phase so that is out.

VFD's with single phase inputs (240VAC splitphase) are readily available in 5hp output ratings. The motor...
Forum: LIVE PLC Questions And Answers February 7th, 2018, 08:48 AM
Replies: 2
Views: 213
Posted By DickDV
It may be that a fixed speed (25hz) is programmed...

It may be that a fixed speed (25hz) is programmed to the reverse control input. This can easily happen since many drives permit multiply terminal assignments.
Forum: LIVE PLC Questions And Answers February 6th, 2018, 08:28 AM
Replies: 26
Views: 1,369
Posted By DickDV
I always try to set up a VFD/Motor system so...

I always try to set up a VFD/Motor system so "forward" on the machine is "forward" on the drive. While IEC and NEMA define forward on the motor, I have never paid any attention to it.

I'm more...
Forum: LIVE PLC Questions And Answers February 5th, 2018, 05:40 PM
Replies: 7
Views: 686
Posted By DickDV
While it is true that knowing what drive model we...

While it is true that knowing what drive model we are dealing with would be helpful, in the meantime you might want to take a look at motor current. If it is jumping all over the place while the...
Forum: LIVE PLC Questions And Answers February 5th, 2018, 05:31 PM
Replies: 26
Views: 1,369
Posted By DickDV
Great answer, OkiePC. You are exactly correct. As...

Great answer, OkiePC. You are exactly correct. As for daba, unfortunately, you are exactly wrong for the reasons OkiePC cites.
Forum: LIVE PLC Questions And Answers February 3rd, 2018, 08:05 PM
Replies: 23
Views: 1,275
Posted By DickDV
One of the very significant reasons for...

One of the very significant reasons for specifying a softstarter on a 100hp motor today is that the standard-efficient motors of yesterday had around a 6 times FLA inrush current for across-the-line...
Forum: LIVE PLC Questions And Answers January 31st, 2018, 07:50 PM
Replies: 21
Views: 1,592
Posted By DickDV
On the most recent designs of VFD's, ABB no...

On the most recent designs of VFD's, ABB no longer requires or recommends pre-action switches on disconnects in VFD output circuits.

Not sure I'm comfortable with that especially over 100hp, but...
Forum: LIVE PLC Questions And Answers December 15th, 2017, 06:04 PM
Replies: 10
Views: 828
Posted By DickDV
Check to see if the motors have permanent magnet...

Check to see if the motors have permanent magnet fields.
Showing results 1 to 25 of 500

 
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