Reading '

Reply

  #1  
Old 11-03-13, 08:25 AM
Member
Thread Starter
Join Date: Aug 2013
Location: United States
Posts: 65
Received 0 Votes on 0 Posts
Reading '

Part # on side of this fan relay: 42-21571-01, for a Rheem 15KW Electric
Furnace.

This olive-colored pic of the relay is supposed to be the same part # as above. I'm aware that online pics are sometimes substituted when the exact pic is not available. The difference here is.... on the actual relay, the flat part of the quick disconnect (#4) laying flush against the relay body covers a larger area, as in the red rectangle I've added. I guess that makes sense, because that would give continuity to #4 & #6 as is shown in the diagram (#6 is not labeled in the diagram, as it is also not labeled on the actual part diagram, but it is shown on the olive-colored pic).

The relay diagram is shown with the coil energized, resulting in continuity between #4, #6 & #5 ? If that's correct, what happens when the coil is de-engergized... the other side of the movable contacts with the half circles, make contact with #4 & #2 ?

What the two bare metal posts recessed in the bosses for? Test points?
 
Sponsored Links
  #2  
Old 11-03-13, 08:42 AM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,416
Received 14 Votes on 11 Posts
Your picture did not post but that looks like a standard single pole double throw relay with a 24 volt coil.
 
  #3  
Old 11-03-13, 08:45 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 54,219
Received 477 Votes on 447 Posts
That relay is called a SPDT type. Ignore the terminal #6 as it only adds confusion to the mix.
Terminals 1 and 3 are the coil
Terminals 4 and 5 are normally closed
Terminals 4 and 2 are normally open

Name:  r.JPG
Views: 302
Size:  43.6 KB

I don't know what the recessed posts under the relay are for.
 
  #4  
Old 11-04-13, 07:25 PM
Member
Thread Starter
Join Date: Aug 2013
Location: United States
Posts: 65
Received 0 Votes on 0 Posts
I thought normally closed meant no power applied to the coil (in this case, since NO or NC is not marked anywhere). Not so?
 
  #5  
Old 11-04-13, 08:25 PM
Houston204's Avatar
Forum Topic Moderator
Join Date: Oct 2009
Location: Texas
Posts: 7,416
Received 14 Votes on 11 Posts
A closed circuit will pass current.
An open circuit will not pass current.
 
  #6  
Old 11-04-13, 10:01 PM
Member
Thread Starter
Join Date: Aug 2013
Location: United States
Posts: 65
Received 0 Votes on 0 Posts
plumducy
I thought normally closed meant no power applied to the coil (in this case, since NO or NC is not marked anywhere). Not so?
Okay, I mis-spoke there, and one more question should clear it up for me... Is the diagram in PJ's pic showing the coil energized or de-energized?

And I'm assuming that the two bars with the half-circles at their ends are a movable set of contact points (responding to the coil's magnetic field), which are physically connected, but not electrically of course.
 
  #7  
Old 11-04-13, 10:06 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 54,219
Received 477 Votes on 447 Posts
The coil is not energized. The diagram on a relay is always at it's non powered state.
The two bars is the plate that moves with the contacts on them.

That diagram I posted is right from the side of the relay. Most relays either have a diagram like that on them or the contacts are marked as common, NO and NC.
 
Reply

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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: