MCC Design References

[Jantolov]

Hello all,

I am putting together some MCC single lines and was curious if anyone was aware of a good reference. I am looking to cover things like, when to use soft-starter? When to use MCP/Breaker/Fuse...etc.

If anyone has a good MCC/VFD/Starter reference they can point me to I would appreciate it.

Otherwise i will have to post my questions individually

 

[Jraef]

All mfrs publish a design guide for their MCC offering, but the few questions you posted here are not the things they will address.

MCP / Breaker / Fuse is really split between only two philosophies: Breaker or Fuse. There will never be any agreement among a group of electrical professionals as to the superiority of one over the other, it's kind of like religion and politics. But in the breaker camp, the decision as to MCP or Thermal-Mag Breaker is not actually your to make, only the equipment mfr can decide that and MCPs can/will ONLY be used in motor starters.

When to use "soft starters" is often dictated by a local utility, but they will not be specific as to what form of reduced voltage starter, only that one is mandated above a certain HP, which varies from place to place. The decision to use Reduced Voltage Solid State soft starters is usually one made by factoring in cost, physical size and the very nebulous "comfort factor" of the people who will be assigned to service and maintain them. I tend to favor RVSS over all other forms, but I am very comfortable with them and know the ins-and-outs of using them. Some people are intimidated by something they can't watch operate and although we want to think they should "get with the program", I think it's pointless to force something on someone who will not want it.

 

[don_resqcapt19]

.... But in the breaker camp, the decision as to MCP or Thermal-Mag Breaker is not actually your to make, only the equipment mfr can decide that and MCPs can/will ONLY be used in motor starters.

You can't tell the MCC manufacturer that you want one or the other at the time of the price quote?

 

[weressl]

All mfrs publish a design guide for their MCC offering, but the few questions you posted here are not the things they will address.

MCP / Breaker / Fuse is really split between only two philosophies: Breaker or Fuse. There will never be any agreement among a group of electrical professionals as to the superiority of one over the other, it's kind of like religion and politics. But in the breaker camp, the decision as to MCP or Thermal-Mag Breaker is not actually your to make, only the equipment mfr can decide that and MCPs can/will ONLY be used in motor starters.

When to use "soft starters" is often dictated by a local utility, but they will not be specific as to what form of reduced voltage starter, only that one is mandated above a certain HP, which varies from place to place. The decision to use Reduced Voltage Solid State soft starters is usually one made by factoring in cost, physical size and the very nebulous "comfort factor" of the people who will be assigned to service and maintain them. I tend to favor RVSS over all other forms, but I am very comfortable with them and know the ins-and-outs of using them. Some people are intimidated by something they can't watch operate and although we want to think they should "get with the program", I think it's pointless to force something on someone who will not want it.

I slightly disagree here.

The use of RVS either SS or other type starer is entirely the users or to be more accurate the engineers choice. The decision is made based on the mechancial needs of the driven equipment and/or based on the load flow and transient stability studies. The requirement could come from either of the two sources. On large systems co-operation with the Utility may be necessary. The only system I've ever ehard of was a cemnt mill aplication where a 60MW motor start had to be co-ordinated with the Utility as they were only able to support the start by some paralleling switching.

 

[Jraef]

You can't tell the MCC manufacturer that you want one or the other at the time of the price quote?

Sometimes, some sizes maybe. But if you say you want a size 1 FVNR starter with a TM breaker instead of an MCP, most likely you will get a response telling you "That makes it a special"; translate $$$ and added delivery time.