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 April 20th, 2017, 02:25 PM   #16
Mickey
Lifetime Supporting Member
United States

Mickey is offline
 
Mickey's Avatar
 
Join Date: May 2003
Location: Palmdale,Ca
Posts: 9,851
Quote:
Originally Posted by GaryS View Post
Let me follow up with this
the output is an OW16 card that's a relay output ( NO leakage)
OFF)
Quote:
The card is a 1756-OW16I

Take a look at the pdf I post above. (leakage is 1.5ma per point)
__________________
Mickey

If you want happiness for an hour-take a nap. If you want happiness for a day-go fishing. If you want happiness for a month-getmarried. If you want happiness for a year-inherit a fortune. If you want happiness for a lifetime-help someone else.
----- Chinese Proverb

Last edited by Mickey; April 20th, 2017 at 02:27 PM.
  Reply With Quote
Old April 20th, 2017, 03:18 PM   #17
GaryS
Member
United States

GaryS is offline
 
GaryS's Avatar
 
Join Date: Aug 2003
Location: Lancaster Pa.
Posts: 511
I still say its a grounding issue the snubber resister is about 200,000 ohms
there is just no way to have a voltage level that high if it's connected to any load at all
the leakage at 120VAC worst case would only be .75ma I would expect it to b far less then that anything connected would drain the voltage down to nothing. if you connected a high impedance volt meter on the unconnected wire from the output the reading would be 120VAC not 87VAC . that can only happen if the source is floating. if that's the case any voltage is possible you could even see 480VAC on that line at some point. floating grounds cause more problems and are harder to find than any other problem you will have.
  Reply With Quote
Old April 20th, 2017, 03:39 PM   #18
labeledas
Member
Canada

labeledas is offline
 
labeledas's Avatar
 
Join Date: Apr 2010
Location: Peace River Alberta
Posts: 524
sounds like a floating voltage to me as well.

I have seen the leakage from a OW16I drive a small relay but the voltage from the card contacts was the same as my source 120VAC.
  Reply With Quote
Old April 20th, 2017, 06:08 PM   #19
James Mcquade
Member
United States

James Mcquade is offline
 
Join Date: Oct 2007
Location: Tennessee
Posts: 1,935
As I see it, you have several issues to deal with.

1. 400 ft between buildings means only one thing, different power sources and grounding, so you must use the same power source from the interface to the other building and back. You CANNOT use power from both buildings !
NEC 70 - cannot quote book, chapter, and verse.

2. a distance of 400' between buildings means 400 ft from building A to building B. You then go thru the isolated output, then 400 ft from building B back to building A. A total of 800 ft. You must size the wire to account for voltage loss, I would say 3 or 4 wire sizes, my rule of thumb, 1 size for every 200 ft of wire.

3. wiring must be run in its own conduit.

4. wire color must me orange to signify interface wiring and power from an alternate source. See NFPA79.

5. alternate power source placards must be on the plc door.

some rules may have changed since I did design on that scale.
if I am wrong, someone please correct me

regards,
james
  Reply With Quote
Old April 20th, 2017, 07:43 PM   #20
Bit_Bucket_07
Member
United States

Bit_Bucket_07 is offline
 
Bit_Bucket_07's Avatar
 
Join Date: Feb 2013
Location: Southeast US
Posts: 1,226
Quote:
Originally Posted by GaryS View Post
Let me follow up with this
the output is an OW16 card that's a relay output ( NO leakage)
if you were reading 87V at the receiving end with the output ON forced or otherwise then you have a serous grounding problem that needs to be addressed.
Not necessarily. It's not true that relay outputs have no leakage current. The typical impedance of a 120 VAC input is quite high, so this output isn't heavily loaded.
__________________
  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
ControlLogix Add-On instruction input and output behaviour Question thefatcontroller LIVE PLC Questions And Answers 10 November 21st, 2008 09:04 PM
Output Forces in ControlLogix mckeeal LIVE PLC Questions And Answers 1 October 23rd, 2007 06:42 PM
Data Echo in ControlLogix Output Modules Tayyab LIVE PLC Questions And Answers 2 July 2nd, 2007 12:01 AM
Forcing OFF josesaucedo LIVE PLC Questions And Answers 21 March 29th, 2007 03:06 PM
Setting Output Voltage on AB ControlLogix bcraig LIVE PLC Questions And Answers 15 June 18th, 2003 07:36 AM


All times are GMT -5. The time now is 02:55 AM.


.