Back-to-Back MV MCC

We have Square D, back to back 480v MCCs.

Thank you, Mr. Kilgore Trout,

However, my question is back to back MV MCC, not 480V LV MCC.

Regards

Would you plz explain what do you mean by back to back MCC

MCC means LV Motor control Centre.Ie LV AC Motor starter controls of various LV Motors are arranged in compartmentalised arrangement of suite of cubicle,If there is one row of these motor controls centre , then it is called as Single front arrangement of MCC.On otherhand due to space restrictions in control room, two sets motor control centres are placed back to back and this arrangement is called as Back to back MCC.

Thank you for your clear explanation, Mr. V.Ambarani.

thanks Mr.Ambarani............

u want to mean it,s just like Double box switchgear........one front box & another rear box switchgear panel................but what,s the way of cable entry.........

DearSh.Prithwiraj,

In double front LV MCC , the out going cables are taken out through cable alleys located in front and back side of MCC suite.

I don't know of anyone who does that. Spacings on bus bar clearances are not conducive to that kind of arrangement.

Besides, what are MV MCCs anyway? There is MV switchgrear, some of which has been adapted to include motor controllers. But unlike Low Voltage which has different design specs between Motor Control Centers and Low Voltage Switchbards, there is no distinction in MV.

I checked the definition in the NFPA NEC 2008 book this morning--High voltage is > 600v nominal(490.2) and low is <208/240.

I didn't find medium voltage and have never heard that--That is why I posted the 480v figure to define what we have--Back to back MCC sections in four different substations.

If high voltage means something besides >600v, then how about being specific about the voltage you call MV or what you have? What is your voltage, anyway?

Thank you Mr. kilgore Trout,

I also went through IEEE 141-1993 (red book) for standard voltages.

IEEE 141 says;

LV 120..600V

MV 2.4 .. 69 kV

HV 115 .. 230 kV

EHV 345 .. 765 kV

In European standad, MV is 5..35kV

Thank you, Mr. JReef.

I mean MV MCC is a sort of switchgear, but to control MV motors. Just for practical purpose, we call MV switchgear for CB (circuit breaker) panels, and MV MCC for fused contactor panels. MV switchgears are used for incoming and transformer feeders, and MV fused contactor panels are for motor branches.

ANSI and IEEE are the arbiters of definitions such as "High Voltage" and "Medium Voltage", not the NEC, and that does cause a fair bit of confusion. Medium Voltage is officially considered to be >1000V and < 35,000V in North America, but in other countries the HV cutoff may be lower.

ANSI Medium System Voltage Chart

Thanks JRaef.

I did find the 1000v-35kv on the web with a search but it didn't cite the source so I got the NEC code book out when I got to work.

Akihito-san,

There was one installation I have seen this Back-to-Back MV (5kV Class) MCC or Swgr, in nuclear power plant in Zagreb, Yoguslavia (1978).

But now, no more.... maybe, if you want to qualify this to the vendor(s), they might give you a chance.

Why, do your space limits you to line-up your MCC?

Eren

Dear All,

Today I met an engineer at Areva factory in Jakarta. He told me Areva's MV MCC can be arranged as back to back, since their MV MCC has no rear access required. All installation and maintenance work can be done from panel front.

Thank you everybody.