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Search: Posts Made By: Tom Jenkins
Forum: LIVE PLC Questions And Answers Today, 01:13 PM
Replies: 7
Views: 314
Posted By Tom Jenkins
I think there is some confusion between the...

I think there is some confusion between the torque demand of the load and the torque capability of the motor. They aren't always equal.

For a centrifugal pump, for example, the torque demand of...
Forum: LIVE PLC Questions And Answers February 19th, 2021, 01:49 PM
Replies: 10
Views: 477
Posted By Tom Jenkins
+1

+1
Forum: LIVE PLC Questions And Answers February 13th, 2021, 11:11 AM
Replies: 22
Views: 1,196
Posted By Tom Jenkins
That seems like the most likely cause to me.

That seems like the most likely cause to me.
Forum: LIVE PLC Questions And Answers February 12th, 2021, 09:53 AM
Replies: 22
Views: 1,196
Posted By Tom Jenkins
Downhole pumps don't usually have a standby - it...

Downhole pumps don't usually have a standby - it gets pretty cozy in the well.
Forum: LIVE PLC Questions And Answers February 11th, 2021, 10:10 AM
Replies: 22
Views: 1,196
Posted By Tom Jenkins
A possibility is that something jammed an...

A possibility is that something jammed an impeller, locked the motor, snapped the coupling, and the current pushed the starter over the edge. Another possibility is that the lack of the backspin...
Forum: LIVE PLC Questions And Answers February 5th, 2021, 04:09 PM
Replies: 12
Views: 541
Posted By Tom Jenkins
When I was designing rectangular clarifier drives...

When I was designing rectangular clarifier drives we always included a torque limiting clutch like a Centric ( https://www.bostongear.com/products/clutches/mechanical-torque-limiting-clutches ) The...
Forum: LIVE PLC Questions And Answers February 4th, 2021, 06:14 PM
Replies: 9
Views: 681
Posted By Tom Jenkins
I used to use Cutler Hammer (now Eaton)...

I used to use Cutler Hammer (now Eaton) https://www.alliedelec.com/m/d/a5c0737d8844e10097279ec2dac4d212.pdf
Forum: LIVE PLC Questions And Answers January 22nd, 2021, 02:36 PM
Replies: 14
Views: 986
Posted By Tom Jenkins
:smas:

:smas:
Forum: LIVE PLC Questions And Answers January 22nd, 2021, 09:43 AM
Replies: 14
Views: 986
Posted By Tom Jenkins
Essentially the relay protects the output. It is...

Essentially the relay protects the output. It is cheaper and easier to pull one relay module from the socket and plug in a new one than replace an entire PLC card if use or overcurrent fries the...
Forum: LIVE PLC Questions And Answers January 16th, 2021, 11:22 AM
Replies: 15
Views: 1,244
Posted By Tom Jenkins
Clients have become more and more risk averse...

Clients have become more and more risk averse over the years. You won't be considered by most without the coverage Steve Bailey identified. Note that in most states workman's compensation is mandated...
Forum: LIVE PLC Questions And Answers January 14th, 2021, 10:43 AM
Replies: 45
Views: 3,298
Posted By Tom Jenkins
I think most on-farm power is still 240...

I think most on-farm power is still 240 single-phase 60Hz with a center tap neutral grounded at the service entrance. Some larger operations may have 208/240/480 three-phase 60 Hz. It has been many...
Forum: LIVE PLC Questions And Answers January 6th, 2021, 12:47 PM
Replies: 16
Views: 1,963
Posted By Tom Jenkins
Another way is to set a "Motor Starting" coil...

Another way is to set a "Motor Starting" coil when the first motor comes on but its starting timer hasn't timed out. A contact from this coil can inhibit the second motor starting.
Forum: LIVE PLC Questions And Answers January 2nd, 2021, 09:39 AM
Replies: 75
Views: 11,001
Posted By Tom Jenkins
Congratulations. I semi-retired several...

Congratulations.

I semi-retired several years ago, and don't regret it. I suggest you keep your hand in for a bit to ease the transition. I find I enjoy serving as a consultant, writing articles...
Forum: LIVE PLC Questions And Answers December 28th, 2020, 10:06 AM
Replies: 54
Views: 4,500
Posted By Tom Jenkins
+1 If you have ever had the experience of...

+1

If you have ever had the experience of deconstructing someone else's poorly documented code you will forever after err on the side of "too many" comments.

There is no downside to lots and...
Forum: LIVE PLC Questions And Answers December 27th, 2020, 10:37 AM
Replies: 42
Views: 3,736
Posted By Tom Jenkins
The folks on this forum quite often disagree....

The folks on this forum quite often disagree. They almost never resort to insult and ad hominem attacks when they do. If you can' maintain professional standards in your comments you can be barred...
Forum: LIVE PLC Questions And Answers December 15th, 2020, 11:44 AM
Replies: 27
Views: 2,380
Posted By Tom Jenkins
Thanks. The references to the 386 processor...

Thanks. The references to the 386 processor certainly brought back memories!
Forum: LIVE PLC Questions And Answers December 13th, 2020, 10:34 AM
Replies: 25
Views: 1,914
Posted By Tom Jenkins
This isn't a new contention. It goes back at...

This isn't a new contention. It goes back at least to the '90s when industrial PCs first started to hit the market. The tough, reliable, adaptable PLC will continue to hold a big share of the...
Forum: LIVE PLC Questions And Answers December 10th, 2020, 11:24 AM
Replies: 26
Views: 2,053
Posted By Tom Jenkins
Power factor is like the weather. Everybody talks...

Power factor is like the weather. Everybody talks about it but nobody does anything about it.

That isn't quite true, of course. Power factor correction capacitors are part of some engineers'...
Forum: LIVE PLC Questions And Answers December 8th, 2020, 09:44 AM
Replies: 26
Views: 2,053
Posted By Tom Jenkins
Whether they are users or designers they will...

Whether they are users or designers they will encounter the terms power factor, capacitor, synchronous motor, etc. in the course of their activities. It is my opinion that they should be given basic...
Forum: LIVE PLC Questions And Answers November 26th, 2020, 06:14 PM
Replies: 13
Views: 1,104
Posted By Tom Jenkins
You have to remember that the circuit component...

You have to remember that the circuit component and wire damage is a result of heat, and heat buildup isn't instantaneous. Devices like fuses and circuit breakers have time delays. The higher the...
Forum: LIVE PLC Questions And Answers November 26th, 2020, 11:15 AM
Replies: 8
Views: 733
Posted By Tom Jenkins
Happy Thanksgiving!

Happy Thanksgiving!
Forum: LIVE PLC Questions And Answers November 23rd, 2020, 09:44 AM
Replies: 9
Views: 1,137
Posted By Tom Jenkins
https://www.motioncontroltips.com/how-do-gearmotor...

https://www.motioncontroltips.com/how-do-gearmotors-impact-reflected-mass-inertia-from-the-load/
Forum: LIVE PLC Questions And Answers November 13th, 2020, 01:15 PM
Replies: 11
Views: 1,209
Posted By Tom Jenkins
Unhappy But he also asked about applying 800 V. If he...

But he also asked about applying 800 V. If he applied that to a standard VFD he would probably let the smoke out. I assumed he was trying to get 800 V out from 400 V in. (Shame on me for making...
Forum: LIVE PLC Questions And Answers November 13th, 2020, 10:10 AM
Replies: 11
Views: 1,209
Posted By Tom Jenkins
Load side Voltage on a VFD generally cannot...

Load side Voltage on a VFD generally cannot exceed line side voltage. Above rated frequency, the Volts/Hz ratio is no longer applicable and the drive operates at a constant output voltage to the...
Forum: LIVE PLC Questions And Answers November 7th, 2020, 10:02 AM
Replies: 5
Views: 751
Posted By Tom Jenkins
Thanks guys!

Thanks guys!
Showing results 1 to 25 of 500

 
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