You are not registered yet. Please click here to register!


 
 
plc storereviewsdownloads
This board is for PLC Related Q&A ONLY. Please DON'T use it for advertising, etc.
 
Try our online PLC Simulator- FREE.  Click here now to try it.

---------->>>>>Get FREE PLC Programming Tips

New Here? Please read this important info!!!


Go Back   PLCS.net - Interactive Q & A > PLCS.net - Interactive Q & A > LIVE PLC Questions And Answers

PLC training tools sale

Reply
 
Thread Tools Display Modes
Old July 26th, 2002, 04:33 PM   #1
PhilRey
Member
United States

PhilRey is offline
 
PhilRey's Avatar
 
Join Date: Apr 2002
Posts: 57
Switching vs. linear power supply for PLC I/O

What are your opinions regarding the use of switching vs. linear regulated power supplies?

The power supply will be used to power PLC I/O, solenoids, LED indicators, and 4-20mA transmitters. It will be mounted in the same enclosure as the PLC.

I will be using a 15 amp supply, so the size and heat dissipation are considerably less with a switching supply. However, I am concerned that the noise from a switching supply may effect the PLC or analog signals. I have used both types of supply without noticing any negative effects.

Is there an industry standard regarding the power supply type selection, or am I just worrying about nothing?

Thanks,
-Phil
  Reply With Quote
Old July 26th, 2002, 06:05 PM   #2
Terry Woods
Member
United States

Terry Woods is offline
 
Join Date: Apr 2002
Posts: 3,170
Wellll...

If you don't pick-up scissors, let alone run with them, then you won't put your eye out! At least, not with scissors.

Some systems can tolerate a lot of noise... some can't.

Switching supplies are a source of noise. Sure, the manufacturers put filters on them and they can get the obvious noise down pretty damned good. But when things go wrong, isn't it usually the case that noise in the power supply is considered much later in the troubleshooting process?

When it works, it works! When it doesn't, sometimes you don't know it's the power supply that's not working!

I think an analog supply is more reliable (if it has the right power). I also think it's easier to troubleshoot an analog supply. Not to mention that you can often repair it yourself!

How many times have you replaced switching supplies in a PC? I have analog supplies that have been running for 10 years.

If you limit the number of troublemakers in the game, you have fewer troublemakers in the game.

In the final analysis, it's almost a toss-up. But, I get more peace-of-mind with analog supplies.
  Reply With Quote
Old July 26th, 2002, 06:05 PM   #3
rsdoran
Lifetime Supporting Member
United States

rsdoran is offline
 
rsdoran's Avatar
 
Join Date: Apr 2002
Location: Birmingham, AL
Posts: 7,372
The concept/idea behind switching power supplies was to create an "efficient" coverter. The concept overall works, they are much more effiecient (hence less power/heat). They have their issues though, stability being the major one.

Overall its your choice, I doubt you can go wrong with either as long as you match the ratings to fit your application.
__________________
http://www.patchn.com Industrial Electrical & Maintenance @ www.patchn.com "Tell me and I forget, show me and I remember, involve me and I understand."
  Reply With Quote
Reply
Jump to Live PLC Question and Answer Forum

Bookmarks


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Topics
Thread Thread Starter Forum Replies Last Post
To Latch Or Not To Latch BOWRIDER LIVE PLC Questions And Answers 43 October 21st, 2015 04:19 AM
RE : SLC-5/04 no power supply to processor patten LIVE PLC Questions And Answers 5 January 7th, 2005 01:13 PM
slc 500 power supply problem medo LIVE PLC Questions And Answers 5 June 1st, 2004 08:05 PM
Power Supplies: Linear vs. Switching Dongleboy LIVE PLC Questions And Answers 5 June 11th, 2003 07:02 PM
24vdc power supplies Mickey LIVE PLC Questions And Answers 7 April 4th, 2003 02:23 PM


All times are GMT -5. The time now is 12:39 AM.


.