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Search: Posts Made By: Tom Jenkins
Forum: LIVE PLC Questions And Answers December 6th, 2021, 11:24 AM
Replies: 12
Views: 827
Posted By Tom Jenkins
This actually has nothing to do with the VFD or...

This actually has nothing to do with the VFD or the motor size per se. My bet is that the suction conditions aren't properly considered and the Net Positive Suction Head Available (NPSHA) is less...
Forum: LIVE PLC Questions And Answers December 3rd, 2021, 06:50 PM
Replies: 12
Views: 827
Posted By Tom Jenkins
One of the problems with sizing VFDs is that...

One of the problems with sizing VFDs is that customers want to buy based on hp but the manufacturers want to sell based on amperage.

As a temporary measure, you may be able to limit the max speed...
Forum: LIVE PLC Questions And Answers December 2nd, 2021, 10:45 AM
Replies: 17
Views: 1,347
Posted By Tom Jenkins
I always considered answering dumb questions from...

I always considered answering dumb questions from newbies a low-cost technique for building my future customer base.
Forum: LIVE PLC Questions And Answers November 26th, 2021, 11:04 AM
Replies: 12
Views: 818
Posted By Tom Jenkins
1) The equation for the trend line shown is only...

1) The equation for the trend line shown is only third order. Excel lets you go to sixth. Keep increasing the order until Rē stops increasing.

2) As Dr. Bitboy says, you generally need to use...
Forum: LIVE PLC Questions And Answers November 9th, 2021, 02:46 PM
Replies: 8
Views: 1,097
Posted By Tom Jenkins
Thanks, ganutenator!

Thanks, ganutenator!
Forum: LIVE PLC Questions And Answers November 9th, 2021, 09:57 AM
Replies: 8
Views: 1,097
Posted By Tom Jenkins
I think you should clearly define the control...

I think you should clearly define the control functions you need: start/stop, forward (and reverse?) speed control, monitor motor speed, amps, motor power, etc. Are there critical functions that you...
Forum: LIVE PLC Questions And Answers October 30th, 2021, 01:07 PM
Replies: 6
Views: 1,077
Posted By Tom Jenkins
If jpeg would be OK then use snipit? ...

If jpeg would be OK then use snipit?
https://snipit.en.softonic.com/download
Forum: LIVE PLC Questions And Answers October 30th, 2021, 12:08 PM
Replies: 6
Views: 1,077
Posted By Tom Jenkins
Visio will import .dwg and .dxf formats.

Visio will import .dwg and .dxf formats.
Forum: LIVE PLC Questions And Answers October 20th, 2021, 02:37 PM
Replies: 14
Views: 1,553
Posted By Tom Jenkins
A VFD can't provide an output voltage greater...

A VFD can't provide an output voltage greater than the input, so you won't get 480 VAC out of the drive without a transformer ahead of it. You can get 60 Hz out of a 50 Hz input, but you will have to...
Forum: LIVE PLC Questions And Answers October 16th, 2021, 06:50 PM
Replies: 31
Views: 3,499
Posted By Tom Jenkins
There isn't a "right" answer, but it has been...

There isn't a "right" answer, but it has been thirty years since I did anything but 11x17.

When we drew and lettered by hand 24x36 (D-size) or even 36x48 (E-size) were required because you didn't...
Forum: LIVE PLC Questions And Answers October 8th, 2021, 10:16 AM
Replies: 7
Views: 1,145
Posted By Tom Jenkins
I used page/line number for wiring and PID tag...

I used page/line number for wiring and PID tag number and description for device identification.
Forum: LIVE PLC Questions And Answers October 7th, 2021, 03:44 PM
Replies: 29
Views: 3,594
Posted By Tom Jenkins
I've programmed dozens of systems for wastewater...

I've programmed dozens of systems for wastewater that included pumps and blowers that need to run 24/7. Controlled automatic restart happened when the power came back on. LO/TO procedures were...
Forum: LIVE PLC Questions And Answers October 4th, 2021, 11:00 AM
Replies: 60
Views: 6,405
Posted By Tom Jenkins
Licensure for engineers has been around for...

Licensure for engineers has been around for decades. I've been a licensed Professional Engineer since 1976. The ISA has certification programs too, but I don't know much about them....
Forum: LIVE PLC Questions And Answers September 29th, 2021, 05:36 PM
Replies: 9
Views: 1,073
Posted By Tom Jenkins
:beerchug:

:beerchug:
Forum: LIVE PLC Questions And Answers September 29th, 2021, 10:32 AM
Replies: 4
Views: 903
Posted By Tom Jenkins
+1

+1
Forum: LIVE PLC Questions And Answers September 20th, 2021, 10:49 AM
Replies: 16
Views: 1,384
Posted By Tom Jenkins
Look at the manual for your VFD. Most brands have...

Look at the manual for your VFD. Most brands have a discrete input on the VFD I/O card that changes direction from forward to reverse. Your output should be connected to that. Most brands use 24 VDC...
Forum: LIVE PLC Questions And Answers September 13th, 2021, 11:17 AM
Replies: 7
Views: 824
Posted By Tom Jenkins
I haven't used the motion control products, but...

I haven't used the motion control products, but in the past, I have been very happy with the quality, service, and value from AutomationDirect. In my experience, they are more cost-effective than...
Forum: LIVE PLC Questions And Answers August 29th, 2021, 07:21 PM
Replies: 5
Views: 1,034
Posted By Tom Jenkins
It has two outputs from a common power supply. ...

It has two outputs from a common power supply.
https://cdn.automationdirect.com/static/specs/smartsensor.pdf
Forum: LIVE PLC Questions And Answers August 26th, 2021, 10:09 AM
Replies: 10
Views: 1,341
Posted By Tom Jenkins
https://www.engineeringtoolbox.com/screw-jack-d_13...

https://www.engineeringtoolbox.com/screw-jack-d_1308.html

The torque on the screw will be the motor torque times the gear ratio times the efficiency.

Don't expect a dead-nuts correct answer....
Forum: LIVE PLC Questions And Answers August 24th, 2021, 10:30 AM
Replies: 10
Views: 1,380
Posted By Tom Jenkins
6" is really too large for practical solenoid...

6" is really too large for practical solenoid valve use. I suggest a butterfly valve. There are electric actuators for open/close and modulating service and in that size they are available in single...
Forum: LIVE PLC Questions And Answers August 24th, 2021, 10:23 AM
Replies: 6
Views: 952
Posted By Tom Jenkins
Because the output is non-sinusoidal most...

Because the output is non-sinusoidal most measuring devices don't work well on the output of a VFD, although I can't speak to your specific question. In my experience, the drive itself is the best...
Forum: LIVE PLC Questions And Answers August 23rd, 2021, 09:56 AM
Replies: 12
Views: 1,678
Posted By Tom Jenkins
Sure thing! You can access books, articles, and...

Sure thing! You can access books, articles, and white papers from my website:

https://www.jentechinc.com/publications.php

(And thanks for the kind words.)
Forum: LIVE PLC Questions And Answers August 20th, 2021, 01:17 PM
Replies: 12
Views: 1,678
Posted By Tom Jenkins
Good catch - thanks. Based on the video I assumed...

Good catch - thanks. Based on the video I assumed a centrifugal pump. If it is a PD pump flow is simply linear with speed and the affinity laws don't apply.
Forum: LIVE PLC Questions And Answers August 20th, 2021, 12:56 PM
Replies: 12
Views: 1,678
Posted By Tom Jenkins
It looks to me as if the fundamental calculation...

It looks to me as if the fundamental calculation is simply the linear approximation that atc222 used for his blower. At the base speed they calculate using y = mx + b, with y flow and x power. The...
Forum: LIVE PLC Questions And Answers August 20th, 2021, 10:05 AM
Replies: 12
Views: 1,678
Posted By Tom Jenkins
This is actually a fairly accurate method if you...

This is actually a fairly accurate method if you have an inlet throttled centrifugal blower - it's been used for decades.

The method falls apart if the blower uses VFDs or guide vanes for control...
Showing results 1 to 25 of 500

 
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