NFB - No Fuse Breaker 2

[itsmoked]

Is this the dumbest moniker going or does it actually mean something logical OTHER than the obvious.

I've never seen this term before and now I've seen it 5 times this week. I tried to research it and all I can make out is that:
"No Fuse Breaker" means "Breaker". Whole companies seemed based on supplying 'No Fuse Breakers'.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[che12345]

Dear Mr. itsmoked

Q. " I've never seen this term before ....all I can make out is that:
"No Fuse Breaker" means "Breaker".... Whole companies seemed based on supplying 'No Fuse Breakers'."
A. I recalled some 50+ years ago, I did installed numerous LV " fused-breaker " in Singapore. These were produced by reputable manufacturers in the US. They were not called (moulded case circuit breaker), the term used in Europe; but they were the some in a (plastic [moulded] case) anyway. They were [not] air circuit breaker (ACB), the term used in Europe.
These high kA " fused-breaker" were constructed with three fuses at the out going terminals, in series with the breaker. The breaker and the fuses were housed in (different compartments) but in a [single moulded case]. It was (not a break-through in the breaker technology). The high kA was with the help of the fuses. They were UL tested to >85kA or up to ?200kA .
In Europe, when high kA MCCB [without fuse] being successful tested, the US "fused-breaker" being over-taken by the former.
Today, you don't see any "fused-breaker" on the market, i.e."No Fuse Breaker" means "Breaker" .
Che Kuan Yau (Singapore)

 

[3DDave]

Like Horseless Carriage?

 

[waross]

The fused breakers described by Mr. Che provided excellent protection against very high fault currents.
Back in the day there was an anecdote about a wrench left across some bus bars.
The bus bars were energized and the fuses instantly cleared leaving small burn marks on the wrench and on the bus bars.
Had the bus been protected by the best available NON-FUSED breaker, the damage could have been expected to be extensive.
That was a long time ago.
Note, the fuses also included pins that projected and tripped the breaker, clearing the non faulted phases.

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

 

[VEBill]

I've seen circuit breakers that were built with intentionally thinner wires (internally) to act as secondary fusing in the event of a catastrophic over current fault. If it's related to this topic, then perhaps they were fused breakers?

Disclaimer: not sure.

For my house, I chose magnetically assisted Quick Open [D] circuit breakers. I believe that they have robust internal wiring.

P.S. Google Ads can sometimes cause a topic to follow you around. After I post this reply, I'll probably be bombarded with circuit breaker advertisements for the next day or two. A couple minutes 'shopping' for bikinis can improve web ads quickly. ;-)

 

[waross]

I turned "directed adds" off in Google. Now I am overwhelmed by bikini adds.
At my age I am reminded of the truism;
"A dog may like chasing cars, but if he catches one he won't be able to drive it." grin
I have no problem ignoring side panel adds Heck, I miss most of the bikinis anyway.
It's the adds that cover up what I am trying to read that are annoying, bikini or not.
I'm not sure about the thin wire theory VEBill, unless it was a single pole breaker. A breaker is expected to open all ungrounded lines.

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

 

[itsmoked]

Here's a company that shouts it.

No Fuse Circuit Breaker

Keith Cress
kcress -

http://www.flaminsystems.com

 

[VEBill]

"...single pole breaker..."

Excellent point, and yes it was.

 

[ScottyUK]

Keith, cosmetically those look like a copy of an old Merlin Gerin MCCB design from the late 80's / early 90's. The MCB to the right looks like another old Merlin Gerin design.

 

[jraef]

Dug this up on someone's site, the obvious translation errors are theirs, emphasis is mine. But it confirms my suspicion of what it meant.

difference between the NFB with MCB is the limit value of current that can be served by both ini.MCB tool used for smaller load is typically modest and still can not diubah.sedangkan NFB has a larger current limit and used to secure his load currents more large and in some types of NFB anyone can set its current limit, of course, the greater the value of the current limit higher price NFB

So years ago, if you wanted a breaker with high interrupting capacity or what we would call a "current limiting circuit breaker" in the MCCB size range, you got a breaker that had a set of current limiting fuses inside of it. Here is an example from GE:

Some time in the early 60s, a German company named Klockner Moeller invented a "fuseless current limiting circuit breaker" (I worked for them in the late 70s so my view of the story may be a little skewed by their viewpoint). It used what is basically a horseshoe shaped current path for the contact sets so that as a breaker began to open under fault, the magnetic forces of the current flow would oppose each other on either side of the horseshoe and force the contacts open faster. The higher the current, the higher the magnetic force, the faster they were opened, the result being that the higher the available fault current, the faster the breaker cleared the fault and limited the let-through. At the time, K-M had and maintained an patent on that concept, but licensed it to Westinghouse in North America since they had little to no presence here. So until the mid 1980s, the concept was uncommon. Once their patent expired, everyone else immediately jumped on the bandwagon and it is now the de-factor standard of construction for MCCBs. But for your Asian source cited above, it's either a holdover from early translation of "fuseless" or they are just a little "late to the party" and seem to think it's still something special...



" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[itsmoked]

This is making a lot more sense now. Thanks everyone.

Were those included fuses a little higher rated than the breaker to generally prevent their opening?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[itsmoked]

I got into this because a VFD I'm installing states:

Note the: "No Fuse Breaker"

=====================================
If I opt for a breaker how do I select it?

Which leaves me puzzling out if I wanted to use a CB how does that relate to:
GS4 Amps = 26
or that they then state, use a:
45A Edison Class J (fast response)

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

Rated current = 26 Amps.
26 A x 125% = 32.5 A
They may be allowing a buffer for initial cap charging.
The fuse is not to protect the VFD, except to limit subsequent damage after the first fault.
The fuse is to protect the supply wiring in case of VFD failure.

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

 

[itsmoked]

OK. Thanks Bill!

Keith Cress
kcress -

http://www.flaminsystems.com

 

[LionelHutz]

Does the drive list the fault ratings with various protection devices on the side?

The chart from the manual sure implies it requires fuses for protection. Some VFD's require specific protection devices to achieve their fault rating.

The fuses or breaker in the VFD cabinet does not protect the supply wiring coming to the cabinet.

 

[itsmoked]

Yep Hutz. I agree about the manual and fuses. Most seem to state "'fuse X' if you want UL listing." Seems I saw that somewhere in this particular VFD manual but I didn't see in the quick hack I did for this thread. Drives in my office and I haven't de-boxed it enough to see its label yet.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Bill West]

My, how history goes around in circles. My first reaction was Westinhouse's "NoFuz" sales name from the 1930's for the original moulded case circuit breakers whose virtue was that now panel boards would no longer need fuses and their attendant re-fusing. Then che12345 points out fuses being added back in for current limiting and jraef points out Klockner-Moeller modifying the contacts to eliminate the fuses again. So is the correct name now the "No Fuse -fused -NoFuz breaker?

Bill

 

[waross]

Hey Bill. I'll bet that you remember the old Square D "Multi Breakers" and the origin of the term multi-breaker.

The following picture is not an original Multi-Breaker despite the label. It is a Stab-Loc panel with replaceable breakers, but it illustrates a common configuration of a Square D Multi-Breaker.

This would typically be a 2 pole 40 Amp breaker for a range, a 2 pole 20 Amp breaker for a hot water heater, and 4 15 Amp branch circuit breakers for lighting and receptacle circuits, all in a monolithic unit.
There was one incoming power terminal on the left side and one incoming power terminal on the right side.
If one breaker failed you had to replace the entire unit. The original Square D unit, not the Federal unit pictured.
They were popular in the 40s. I never installed one but I replaced a few with Square D XO panels.

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