Difference between 200A & 600A Loadbreak elbows (or) What does 200A/ 600A mean for a Loadbreak e

[engratcorner]

Hello all,

Does anyone has an idea about 200A & 600A loadbreak elbows? I came across this while designing a pad-mounted transformer. Initially I thought that this ampere rating would be calculated from rated kVA and rated Voltage but for a 75kVA transformer with 13.2kV (L-L) on primary would lead to around 4A. Being that said, these 200A/ 600A loadbreak elbows are connected to primary (such a large rating ones)!! I am confused! I am not sure whether I am approaching in a correct way or not. Can anyone get me out this tangle situation.

Thank you in advance,
Rohit

 

[jghrist]

600 A elbow connectors are not loadbreak. They bolt together and are separable only when de-energized. You might need 600 A connectors if they feed through on a circuit that can carry more than 200 A. You can get various accessories such as a 200 A loadbreak bushing insert that can connect to a 600 A elbow connector and allow a loadbreak elbow to be connected to a 600 A elbow connector (or two connected together for feed-through).

 

[engratcorner]

Hello jghrist,

I appreciate your comment but on what factor do we select 200A/ 600A elbows? Does that depend on primary full load current or secondary full load current of a transformer?

-Rohit

 

[jghrist]

It depends on the maximum current that will flow through the connector. Secondary current does not flow through the connector.

 

[engratcorner]

Yeah, but on a 75kVA transformer with 12.47kV (LL) on primary, full load current is around 3.5A...!! Now I've got an option to pick either 200A/ 600A elbow!! How does that work?

 

[rcw retired EE]

200A Loadbreak Elbows are the smallest standard size used. Don't worry that the current is only 4 A. The 200A connector can carry it. You won't save any money or time trying to find a load break with a smaller amp rating.

As already mentioned, the 600A are not load break. Load break means a suitably trained high voltage electrician can use a hot stick to pull out the elbow and disconnect the transformer. The elbow with its exposed live conductor inside would then be plugged into a dead end "parking" bushing to make it safe.

Load break elbows are a cheap way of doing manual switching in distribution systems.

#16 wire is good for a lot more than 4 amps. But we wouldn't run #16 to that transformer.