×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Magnetic CB trip circuit

Magnetic CB trip circuit

Magnetic CB trip circuit

(OP)
I trying to make heads or tails of a simple trip circuit. I have not seen a circuit such as this but they tell me the wiring is correct as shown in the drawing. Sorry for the crudeness of the drawing.
If the contact below the breaker closes, it trips the breaker. I am totally missing something if this is how it is actually wired. Sure the polarity reverses but at the same time, there is not potential difference across the breaker to develop a current. What is the theory of operation of this circuit? I am probably having a major brain malfunction as it has been a long couple weeks.

RE: Magnetic CB trip circuit

A shunt trip?
A small solenoid inside the breaker that mechanically trips the breaker?

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Magnetic CB trip circuit

That's nonsense. You're correct, something is fishy/wrong.

The drawing is entirely missing a shunt-trip that is mechanically tripping the breaker from next to it, as Bill suggests, or that's not a contact it's an idiot-light that only lights once the breaker opens and specifically it's a neon idiot-light.



Keith Cress
kcress - http://www.flaminsystems.com

RE: Magnetic CB trip circuit

(OP)
Problem solved. The contact is closed when everything is ok, not opened. Obviously, this allows next to no current flow through the breaker. If there is an issue, the contact opens, diverting most of the current through the breaker causing it to trip. To top it all all off, it is totally unnecessary...the breaker has some aux contacts, which are then placed in series with a trip circuit. I am not sure why they didn't just use the contact that is shown in my drawing in the trip circuit...(if it is not an adequately rated contact, then use an aux relay). Goofiest thing I have ever seen...
Thanks all and sorry for the drawing link and the later than I like reply.

RE: Magnetic CB trip circuit

(OP)
Yes it is Keith! Thanks

RE: Magnetic CB trip circuit

1000 Ohm at 120 Volts? That's 0.12 Amps.
It will take a very long time to trip a 0.125 Amp breaker.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Magnetic CB trip circuit

Yep. More like a temp sensor then. If the breaker reaches 120F it trips.

Keith Cress
kcress - http://www.flaminsystems.com

RE: Magnetic CB trip circuit

(OP)
Sorry, forget to mention it is a variable resistor and is set at something lower than 1k. This is an explosion proof box and I didn't want to remove 30 plus bolts to measure it.

RE: Magnetic CB trip circuit

Reminds me of opening an explosion proof breaker panel.
3/4" bolt heads.
Just crack each bolt loose.
Then drop a 1/2" bolt backwards into a 3/4" socket so that the shank protrudes out of the back of the socket and the bolt head is deep inside the socket.
Chuck the bolt shank in a 1/2" battery drill and spin away.
No time at all.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Magnetic CB trip circuit

Be cautious if using a power tool to wind cover bolts out on stainless steel or aluminium enclosures, the threads can easily gall and - under our rules at least - field repairs aren't allowed on flameproof (explosion-proof) equipment. At the very least keep the speed right down.

RE: Magnetic CB trip circuit

Hi Scotty. Let me take advantage of your information to add:
Anyone who doesn't lubricate stainless or aluminum threads will eventually gall the threads. Guaranteed.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: Magnetic CB trip circuit

(OP)
Yeah, I don't need to know the R that bad. I know its smaller than 1k and that is enough for me. I can imagine the look on my Super's face when I ask him to shutdown production and bring the box outside for measuring the R - not going to happen.
Our's is not a lid but a vertical cover - making it even funner to remove.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

White Paper - How to Capitalize on HVAC/R Trends to Drive Business Growth
According to Steve Yurek, CEO of the Air Conditioning, Heating and Refrigeration Institute, the HVAC/R industry is facing change on all fronts. This includes challenging trends on contractors and distributors like new refrigerants, growing automation, complex sensors and monitoring, green initiatives and a technician shortage. We look at these trends and outline actionable insights on how it all can be turned into a competitive advantage and business opportunity. Download Now
eBook - Manufacturing the Cars of Tomorrow
In this ebook, we'll explore how additive manufacturing is going to transform the way cars are made. This includes commentary from thought leaders such as Ford's CTO, Ken Washington, Customer case studies of ways 3D printing is being used today, and a variety of part examples where 3D printing is already impacting how automobiles are made. Download Now
White Paper - Smart Manufacturing for Semiconductor
New technologies and approaches present great opportunities for semiconductor manufacturers to achieve high levels of innovation, yield and improvement. This white paper explores some of these cutting-edge technologies and how they can be applied effectively in the semiconductor industry. Read about how Smart Manufacturing is transforming the semiconductor industry. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close