shunt

Status
Not open for further replies.

JdoubleU

Senior Member
Could someone help me make since of this word. I've heard the term shunt trip breaker. I've heard people say that devise has been shunted. What is a shunt.
 

roger

Moderator
Staff member
Location
Fl
Occupation
Retired Electrician
Basically it means to provide a parallel path of lower resistance into a circuit. The lower resistance path will shift/shunt the current flow from another path.

Roger
 
roger said:
Basically it means to provide a parallel path of lower resistance into a circuit. The lower resistance path will shift/shunt the current flow from another path.

Roger


To add what Roger has posted, think of a "jumper" conductor put in place to provide the parallel path. Shunts can be all different kinds of lengths as well. Most are relatively short.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
all the definitions were wonderful.... now, how does that explain a "shunt" trip breaker :)
 

coulter

Senior Member
Jakewhis said:
Could someone help me make since of this word. I've heard the term shunt trip breaker. I've heard people say that devise has been shunted. What is a shunt.
As roger said, "Shunt" means parallel, but not in the usual sense. The OC trip element sensors are in the line main current flow path - "series" one might say. The shunt trip element is a "parallel trip element" to the OC trip element - mechanically parallel. A shunt trip on a CB has an actuation coil, takes 24 - 120 AC/or DC to activate.

Different use of the work "shunt" for "shunt field" or "shunting a device"

carl
 

quogueelectric

Senior Member
Location
new york
A shunt trip breaker is a little tricky to understand beacause it has a little magnetic coil in it that needs external power to activate.
You have to provide an external power source sufficient in voltage to activate the relay.
A common application would be a shunt trip breaker to a kitchen panel feeding electric fryers . The breakers themselves will have usually 2 little stranded black wires about 10 inches long coming out of the side or the back of the breaker.
When you energize these 2 wires the breaker will trip. The ansul system has microswitches in its trip mechanism. For example a fryer catches fire and trips an ansul head when the ansul is released on to the fire it trips the internal microswitches.
Which sends an alarm to the fire alarm pannel and simultaneously closes a switch to the shunt trip breaker which is fed with a switchleg of the propper voltage to trip the breaker. The switch closes the relay is energized and the magnetized relay trips the breaker turning off the power to the fryers.
I hope this helps a lot of people are confused about this so dont feel bad.
 
L

Lxnxjxhx

Guest
If you measure the millivolt drop in a length of wire due to the current that is flowing through it, the wire is a (temperature sensitive) shunt.
 

dbuckley

Senior Member
Jakewhis said:
I've heard the term shunt trip breaker. ... What is a shunt.

These are two very different things, with only a tenuous connection.

Roger has given an example of a shunt, basically a circuit element in parallel, for some specific purpose other than simple paralleling of a circuit.

A shunt trip breaker is a type of circuit breaker, almost always whereby an external voltage applied to a coil isolated from the contacts causes the breaker to open.
 

mdshunk

Senior Member
Location
Right here.
Other than shunt trips, the only other shunts I know about are used in high-current DC lines to expand the range of an ordinary DC ammeter. In the image below, the ammeter would hook on the two brass screws, and the DC bus bars would have this shunt spliced in via the holes in the copper. I don't know where all these are used, but they're an important part of the instrumentation in an electroplating plant.

2-hi-res.jpg
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
Marc,
That shunt is huge (of course plating currents are very high), but I have seen much smaller ones in DC drives and things like that. However I don't think you connect an ammeter to the screws....I believe it would be a millivolt meter with a meter face labeled in amps. You are really measuring the voltage drop across an know resistance.
 

mdshunk

Senior Member
Location
Right here.
don_resqcapt19 said:
Marc,
That shunt is huge (of course plating currents are very high), but I have seen much smaller ones in DC drives and things like that. However I don't think you connect an ammeter to the screws....I believe it would be a millivolt meter with a meter face labeled in amps. You are really measuring the voltage drop across an know resistance.
Right. The meter I typically used for that came with stickers to make it whatever kind of meter I wanted it to represent itself as. I liked the simpson Hawk meter for that.
 
L

Lxnxjxhx

Guest
Plus the freq. response is almost unlimited, unlike a clamp-on ammeter.

That picture shows the mother of all shunts.
 

coulter

Senior Member
langjahr@comcast.net said:
Plus the freq. response is almost unlimited, unlike a clamp-on ammeter. ...
Interesting comment. I've never seen any specs on the frequency response of a current shunt. Is this common for your work?

carl
 
L

Lxnxjxhx

Guest
. . .seen any specs. . .

. . .seen any specs. . .

Yeah, I guess I've looked at mostly wideband, high freq. stuff.
And, if I made a mistake, a 50 cent integrated circuit was toast. If PoCo makes a mistake it's on the evening news.

Also, a shunt should have a zero tempco-

http://en.wikipedia.org/wiki/Constantan

Along with a 1 mA analog meter movement, coat hanger wire makes a good shunt for a car battery ammeter, if you don't mind drawing your own very-non-linear meter scale.
 

Hrushaabh

Member
Jakewhis said:
Could someone help me make since of this word. I've heard the term shunt trip breaker. I've heard people say that devise has been shunted. What is a shunt.
Hey,
'Shunt' basically means 'to be connected in parallel'....let us take the case of an ammeter....an ammeter consists of a galvanometer connected in parallel with a very high resistance....this resistance connected in parallel is called as shunt...we can also say that "An ammeter is constructed from a galvanometer by shunting it with a resistance". Also take the case of a DC sunt motor...It basically is called so because it consists of an armature shunted with a field winding and both are connected across a DC source.
Hrushaabh
 

POWER_PIG

Senior Member
coulter said:
As roger said, "Shunt" means parallel, but not in the usual sense. The OC trip element sensors are in the line main current flow path - "series" one might say. The shunt trip element is a "parallel trip element" to the OC trip element - mechanically parallel. A shunt trip on a CB has an actuation coil, takes 24 - 120 AC/or DC to activate.

Different use of the work "shunt" for "shunt field" or "shunting a device"

carl
Shunt coils only come in 24 to 120 volts?
Ive wired many a 277/480 shunts. Just saying, not limited to 24 through 120v
 

iwire

Moderator
Staff member
Location
Massachusetts
The only shunts I have wired where 120 volt and that includes the shunts on 480 volt breakers, the shunt voltage has nothing to do with the voltage the breaker is used for.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
quogueelectric said:
How did I do Augie??

great, of course.
as discussed later, I was simply trying to point out that there is a difference in the same term as applied to a breaker and a "series" shunt.
 
Status
Not open for further replies.
Top