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Search: Posts Made By: DickDV
Forum: LIVE PLC Questions And Answers June 1st, 2018, 11:13 AM
Replies: 2
Views: 393
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: 328
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: 1,265
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: 1,471
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: 400
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: 1,305
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: 1,471
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: 1,471
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: 1,305
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: 602
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: 533
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: 427
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: 642
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: 1,108
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: 518
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: 196
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: 1,248
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: 615
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: 1,248
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: 1,171
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: 1,455
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: 688
Posted By DickDV
Check to see if the motors have permanent magnet...

Check to see if the motors have permanent magnet fields.
Forum: LIVE PLC Questions And Answers December 4th, 2017, 08:27 AM
Replies: 2
Views: 323
Posted By DickDV
I would suggest Highland Controls as well. I...

I would suggest Highland Controls as well. I don't do lead/follow enough to help without spending an hour studying the manual. Good luck.
Forum: LIVE PLC Questions And Answers December 2nd, 2017, 07:30 PM
Replies: 4
Views: 439
Posted By DickDV
Generally speaking, Mitsi is certainly one of the...

Generally speaking, Mitsi is certainly one of the best brands out there. However, that is meaningless unless you get good local (even on-site) technical support. Weg is not a "bad" brand so I'd...
Forum: LIVE PLC Questions And Answers November 19th, 2017, 04:25 PM
Replies: 12
Views: 1,036
Posted By DickDV
Regarding willxfmr's statement about motor...

Regarding willxfmr's statement about motor failure above, consider that 3hz is 1/20th of 60hz which, in motor manufacturer language, is a 20/1 speed turndown ratio. By willxfmr's statement, any...
Showing results 1 to 25 of 500

 
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