Difference between switchgear and MCC 1

[Portscheller]

Wanted to find out the difference between switchgear and MCC. Drawing uses the term switchgear, but in manuals the same switchgear is referred to as a MCC. Is that just because it is switchgear that contains motor control circuits? Thanks!

 

[dpc]

Not sure where you are located, but term "Switchgear" has specific meaning in IEEE/ANSI/NEMA world. For low voltage systems, switchgear is generally applied to distribution gear meeting requirements of ANSI C37. Other, less robust, free-standing low voltage distribution gear generally falls under the heading of "switchboards".

"MCC" stands for Motor Control Center and is generally a manufactured assembly of motor starters and feeder breakers in a standard configuration and construction, per NEMA standards.

 

[jraef]

There are significant construction differences as well. MCCs use removeable "buckets" for motor controllers up to a certain size (NEMA size 4 or 100HP @ 460V) that stab into the bus bars for quick replacement. They can have "feeder breakers" as well and they are also usually in buckets up to 250A frames. Switchgear, on the otherhand, generally does not contain motor controls in low-voltage systems and the breakers are not required to be removeable using stab-in connections. They also fall under different UL testing classifications as well. LV Switchgear is usually UL1558, MCCs are UL485

Once you get into Medium Voltage the differences tend to blur. Then again, the definition of Switchgear gets more complicated as well, i.e. Metal Clad or Metal Enclosed, Load Interrupter or Arc-Proof etc. In MV systems, especially Metal clad, motor control is often mixed in with "Switchgear" because it is often too expensive to have separate systems and the number of MV motor controllers is usually relatively small.

"Venditori de oleum-vipera non vigere excordis populi"

 

[Portscheller]

Thanks jraef. The switchgear is 5.5kV Metal Clad. You confirmed my assumption that the MCC is mixed in with the switchgear (though I also assume that the MCC would have its own separate bucket located in the switchgear lineup).

 

[jraef]

Yes, but because the M-C switchgear is so expensive, and is actually akin to having a "bucket" anyway, most systems using it will just add the necessary motor control elements to the draw-out breaker system, thus making it a "starter" per se.

BTW, just to correct myself, the LV UL MCC classification is UL845, not 485.

"Venditori de oleum-vipera non vigere excordis populi"