HV Switchgear 2

[raptor6458]

Hello again guys,

I'm evaluating an ABB Unigear 6.6kV HV switchgear (well our client considers the 6.6kV as a high voltage) and I'm quite a bit puzzled by their offer. ABB is offering a 2-tier double level switchgear, meaning the upper and lower panels of the switchgear compartment can be occupied by 2 outgoing circuit breakers.

As per my understanding and pls. correct me if I'm wrong, the switchgear compartment should only be occupied by a single incoming/outgoing breakers.

If this is an MCC (LV) I also understand that 2 breakers can occupy the upper and lower panels of the compartment.

Am I already living in the dark ages?

Already browse a lot of material but can't seem to find the right direction.

Can somebody point me to a reference or standards (IEC, IEEE etc)wherein I can say (with proof)to the vendor that their offer is not acceptable and have to propose another. Specs, design basis, etc doesn't say anything about the compartment set-up except for a single or double tier switchgear.

Appreciate for any advise and help you can contribute.

Ciao.

 

[ScottyUK]

You can specify one breaker per tier if you want, but what ABB are proposing is a fairly typical design for a compact board using VCBs or vacuum contactors. You won't find anything in the standards preventing what they are proposing, so if you want 'proof' then look in the project specification. If the spec writer forgot to include this requirement then the options available are either accept it or pay for a variation. Sorry!


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If we learn from our mistakes I'm getting a great education!

 

[slavag]

Hi
What Scotty saied.
It's typical constraction for the MV MCC, for example, and not of ABB only.
Best Regards.
Slava

 

[raptor6458]

Hello scotty & slavag

Thanks for the advise.
Anyway just starting the evaluation and I haven't seen yet a 2 VCB's in a single compartment. Mostly are single CB per compartment.

I guess I've to ask them about the installation, maintenance and safety aspects of the equipment since its going to be a bit crowded.

Thanks guys. Appreciate the help!!!

Ciao.

 

[ppedUK]

2 circuits per tier boards like this are offered by most manufacturers, but are mainly fixed pattern (not sure about the ABB Unigear though). If you are looking for withdrawable switchgear, then this is more problematic with a double tier. It can be done, but access to the top cubicle is difficult.

Your spec must have been fairly loose if that is what ABB are proposing. If you are in a competitive tender situation with a loose spec, they are bound to offer you the most "cost effective" solution.

Personally, I don't like this format, they are way too "compact" for my liking, particularly for higher voltage levels.

 

[raptor6458]

ppedUK thanks for the comments.

Personally too, I don't like the setup. Installation, maintenanace and safety aspects is a bit questionable becoz of too tight a space.

Appreciate your help.

 

[jghrist]

Are you sure that there are two breakers in one compartment? Two separate compartments, one above the other, would be typical.

 

[raptor6458]

Hi jghrist,

Basically, out here for an HV switchgear, the vertical panel (w/c is compose of 2 or 3 section or cubicle)are called compartment.
You're right it is two separate compartment and a metering and instrumentation compartment/cubicle between them.
So the setup is 1-VCB in the upper cubicle, metering/instrumentations in the middle and 1-VCB in the lower cubicle.

Hope I didn'tconfuse this time.

Thanks.

 

[EEJaime]

Many manufacturer's, ABB, Cutler Hammer, S&C, others, offer the two breaker per sections configuration, at least up to about 15kV class gear. Higher Voltages are limited to the single breaker per section configuration. These are included in the manufacturer's catalogs as standard product.

 

[rcw retired EE]

There are many, many installations in North America with two high breakers at 15 kv and lower voltages. The outgoing cables come in the back. Usually there is enough room for the two sets of cables. Barriers can be provided to separate the cables in the rear.

One problem we ran into is insufficient room on the single center section for control switches, meters, protection relays, lockout relays and indicating lights. Wiring room is also limited for auxiliary contacts and control cables. The solution is to use the programmable relays' software keys and other functions to operate and monitor the breakers and use a data link to provide remote control. That eliminates the wiring issues.

 

[raptor6458]

EEJaime

Seldom do I see a proposal like this, some client prefers a single breaker configuration (for HV). Mostly I saw are on LV switchgears and MCC.

rcwilson,
Thats what Iam afraid of, compartments getting crowded. It will be up to the client to decide since there were a few loopholes.

thanks for the comments and help guys.

cheers!!!!!

 

[antigfk]

I bought some ABB Safegear 5kV arc-resistant about a year and a half ago. It was two-high (meaning breaker on top of controls cubicle on top of breaker... each a separate compartment) for most of the lineup. Feeders, main breakers, & feeder breakers can easily be accomodated by two-high switchgear. For synchronous motors feeders, you still want to use a single-compartment vertical section because of all the controls/relays you need for the synch motor. It really comes down to personal preference... obviously maintenance personnel would like one-high sections, but two-high sections can reduce floor space and save money on pre-fabricated powerhouses.