Why "Shunt trip" breaker?

[Open Neutral]

We know what it is, and what it does,
BUT
the name?

Where's the "shunt" in the solenoid inside the breaker?

 

[topgone]

We know what it is, and what it does,
BUT
the name?

Where's the "shunt" in the solenoid inside the breaker?

"Shunt" meaning, "in parallel" with other tripping contacts. As differentiated with the "series" or interlocking contacts.

 

[Open Neutral]

"Shunt" meaning, "in parallel" with other tripping contacts. As differentiated with the "series" or interlocking contacts.

But it isn't.... The coil is in series with the [ STOP button] contacts and the supply voltage...

 

[ActionDave]

But it isn't.... The coil is in series with the [ STOP button] contacts and the supply voltage...

But it's in parallel with the other trip functions of the breaker.

 

[topgone]

But it's in parallel with the other trip functions of the breaker.

Correct! Two opposing design options--> shunt or interlocking!

 

[iwire]

But it isn't.... The coil is in series with the [ STOP button] contacts and the supply voltage...

We are not talking electrically in series or parallel. We are talking mechanically in parallel.

The mechanical action of the solenoid is in parallel with the mechanical action of the standard trip mechanism.

 

[mbrooke]

That's dangerously close to the ground up vs ground down or Chevy vs Ford type topics.

If we start debating that I am going to move it into its own thread.

Not meant to debate, just to point out that what we may call something doesn't always reflect the literal definition of said name :thumbsup:

 

[GoldDigger]

Another way of looking at it is that you can trip the breaker by shunting (diverting) a small amount of current around it.
Not only are we not sure of the origin yet, we are not even sure which dictionary entry for shunt was part of the origin.

 

[iwire]

Another way of looking at it is that you can trip the breaker by shunting (diverting) a small amount of current around it.

:huh:

 

[ATSman]

But it isn't.... The coil is in series with the [ STOP button] contacts and the supply voltage...

When they say "in parallel with other tripping functions" they mean that typically a small breaker has (3) ways of
automatically tripping open: Trip Unit [1. Long Delay: sustained overload, like 300% rating 2. Instantaneous: short circuit, like >1000% rating] Shunt Trip, solenoid energized by an external voltage source. On large power breakers, LV, MV & HV class, other trip unit functions exist such as Short Time, Ground Fault, Isq T, etc for system coordination.
"Tripping" is usually referred to as the automatic opening as apposed to the manually opening by operating the breaker handle to off.

 

[Ingenieur]

The 3rd trip can be uv under-voltage
apply power to shunt trip
remove (or reduce) it to uv trip

 

[ATSman]

The 3rd trip can be uv under-voltage
apply power to shunt trip
remove (or reduce) it to uv trip

good point, forgot that one!

 

[Ingenieur]

good point, forgot that one!

we require both to be tripped on oc, toc, gf and loss of egc
capacitive discharge on the shunt (obviously)

 

[Open Neutral]

The mechanical action of the solenoid is in parallel with the mechanical action of the standard trip mechanism.

Ahh, THAT I can accept. Thanks.

 

[Fnewman]

From Schneider Elecrtric

From Schneider Elecrtric

: A shunt trip device is an optional accessory in a circuit breaker that mechanically trips the breaker when power is applied to the shunt trip terminals. The power for the shunt trip does not come from within the breaker, so it must be supplied from an external source.

 

[Tony S]

Various shunt trips in a MG M-Pack 1000A ACB.

Watch out if UV coils are fitted, they get very hot and can burn the skin.

 

[mbrooke]

UV coils?

 

[Tony S]

UV coils?

Under Voltage

 

[iwire]

Various shunt trips in a MG M-Pack 1000A ACB.

Watch out if UV coils are fitted, they get very hot and can burn the skin.

I think we have wildly different ideas of the scale the OP is talking about.

 

[Tony S]

The purpose is the same whatever the size of the breaker.