MCC PDC Sizing

[Ingenieur]

something does not add up
has the 1000 A fuse ever blown

if he has 4 x 300 hp running close to 100% he has 1400+ A

 

[Jraef]

Changing the service size to 1600A will not change the size of the MCC bus, it's still 1200A, and 1200A is just barely enough to handle your existing measured load (4x300A). So unless you are going to replace the MCC or split up the load and add a new MCC, changing the service is an exercise in futility. If it were me, I would split the load and add a new MCC next to it with a new feeder from the PDC.

 

[drktmplr12]

is the MCC main-tie-main and or radially fed?

jraef makes a good suggestion.

consider installing a new 4 section, 1200A mcc with a tie breaker section, main breaker, new feeder, and two starters. one advantage to this is redundant main feeders and you can close the tie breaker and operate at least 3 motors without supervision. this also allows you to perform preventative maintenance on either MCC while still being able to operate 2 motors. You could also close the tie and power all 4 from either side while monitoring operation.

guessing diversity is a slippery slope that we no longer play with. I see older designs where all motors had 0.8 applied.

we only consider n+1 redundancy and size per 220 III or 220.87.

 

[Snyder5150]

something does not add up
has the 1000 A fuse ever blown

if he has 4 x 300 hp running close to 100% he has 1400+ A

Not yet. Thanks for the update.

 

[Snyder5150]

Changing the service size to 1600A will not change the size of the MCC bus, it's still 1200A, and 1200A is just barely enough to handle your existing measured load (4x300A). So unless you are going to replace the MCC or split up the load and add a new MCC, changing the service is an exercise in futility. If it were me, I would split the load and add a new MCC next to it with a new feeder from the PDC.

The work is still under contract and we have been running for about a month. I will be confronting the GC tomorrow. Sorry for the late response but very busy with work as you can imagine. This is something I have been contemplating some of these options.