Breaker Types

[Jmoore284]

Is anyone aware of good documentation breaking down when to use different breaker types? We are performing electrical studies for several facilities and have run into older breakers from multiple manufactures that are not readily identified. If we are lucky their ampacity is marked but nothing indicating their frame/type. My intent is to provide the team with guidance on what type of breaker to use (D, G, J, L, etc.) based on the load being fed. For example, use a type D for motor loads.

I have seen some information from Square D and Allen-Bradley but it is specific to their offering.

 

[che12345]

'..Is anyone aware of good documentation breaking down when to use different breaker types? ... My intent is to provide the team with guidance on what type of breaker to use (D, G, J, L, etc.) based on the load being fed. For example, use a type D for motor loads.'
If you furnish more detail, proposals would be closer to your target.
a) Voltage rating LV (< 1 kV) : ACB, MCB, MCCB or MV (> 1 kV): air, vacuum, GIS...
b) Location, in : Europe, US, Canada ...
c) Compliance to which standard: IEC, ANSI, IEEE, UL; CSA...
d) Rated current: <63 A, <1 kA, <6.3 kA...
e) Rated frequency: 50 Hz, 60 Hz or DC.
f) Application: domestic, industrial, land or marine...
Che Kuan Yau (Singapore)

 

[jraef]

The "D, G, J, L" etc. followed by your statement about using type D for motors sounds like trip curve designations for IEC MCB (Miniature Circuit Breaker) devices, so would not apply to anything in North America where we don't have those. But I have only heard of B, C, D, K and Z trip curves, no G, J or L! The recommended uses for those different trip curves is, in theory anyway, the same regardless of manufacturer, meaning they are a function within the IEC standards for those types of breakers.

On the other hand, "D, G, J, L", if referring to North America, are used as "frame size" designations on some brands of MCCBs (Molded Case Circuit Breakers). In particular, those 4 frame sizes match up to Siemens Sentron breakers, as well as (I think) Eaton C-Line MCCBs. Frame sizes are NOT the same from one brand to another, and have NO RELATION to the use or trip curve. They are strictly about the physical dimensions as related to the current ratings.

So your mention a "type D for motors" would be correct for an MCB trip curve when used for motor loads, but that would not relate to an MCCB, regardless of the frame size being D, G, etc. Until you further define what you are talking about, we can't really help much.


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

 

[che12345]

In the IEC world, LV (<1 kV AC) breakers:
1. ACBs (<6.3 kA) and MCBs (<1 kA) are covered by IEC 60947-2. Most of them having adjustable LSIG tripping characteristics.
2. MCCB (miniature circuit-breaker) is covered by IEC 60898-1. Their non-adjustable magnetic tripping characteristic B (3-5 times rated), C (5-10 times rated), D (10-20 times rated) , K and Z for semiconductor protection.
3. Attention: There is NO harmonization between IEC and ANSI, IEEE, UL etc..
Che Kuan Yau (Singapore)

 

[Peter85]

That sounds like a challenging situation! For general guidance on breaker types, you might want to check out resources from IEEE or NEMA, as they often provide more comprehensive documentation that isn’t brand-specific. Additionally, IEC 60947 might help for classifying breakers by application (like Type D for motors, as you mentioned). If you're dealing with older equipment, cross-referencing manufacturer datasheets or catalogs can sometimes help identify frame types and their appropriate applications.

 

[jraef]

2. MCCB (miniature circuit-breaker) is covered by IEC 60898-1. Their non-adjustable magnetic tripping characteristic B (3-5 times rated), C (5-10 times rated), D (10-20 times rated) , K and Z for semiconductor protection.

That would be MCB, not MCCB. MCCB = Molded Case Circuit Breaker. Different product, different standards.


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