Motor Control Center or not?

[Rock86]

We have a client with an existing MCC and they are looking to upgrade/modify. The motors run 24/7, and only 2 groups of motors need to have A start before B. All of the motors are 208V and no larger than 10HP. There is an alarm system involved incase one of the motors fails.

I have 2 primary questions...
1. Is a motor control center necessarily needed for continuous on/ manual off operations, and all of the alarm equipment? (pretend you are the client, would you want one)
1.a. If you don't think a MCC is needed, what would you use to trigger an alarm situation? Would you stick with a motor contactor is an aux relay just eliminate the lights and switches?
2. If an MCC is need, what manufactures are helpful with equipment selections? I can do all of the calculations of the motor starter and overload device, but our office has not had to design an MCC in a long time, I assume most of you will say Allen Bradly, i am curious if there is anyone else out there.

 

[petersonra]

We rarely suggest MCCs to our customers because of the cost. Mostly we would make a control panel up that houses all the motor starters and aux equipment, to include whatever alarms and status might be needed.

We also do MCCs for some customers who want them, but only a few want them, especially for groups of small motors.

There are companies besides AB that make MCCs. Schneider and Siemens come to mind. We mostly use AB because that is what our customers want most of the time but we get requests for other brands now and then.

We have a deal with AB so price for AB is very competitive, often less than other brands.

We also like AB because we can get all kinds of goodies with it that are preconfigured options like Ethernet switches, and delivery is surprisingly good.

 

[Jraef]

The option to use an MCC vs a control panel arrangement is mostly about the end user's need to maintain operation during a problem, and return to operation as quickly as possible. If you have a control panel arrangement, and one controller has a problem, you have to shut down the entire panel to work on it (safely and/or per OSHA rules). An MCC allows you to disconnect just the one starter by itself, remove it from the stack to service it if necessary, and insert a spare starter in its place to get the process back up and running with minimal disruption. The added cost is typically more than justified by avoidance of down time.

However, if the machine or process will need to shut down completely if any one part of it has an issue, then the MCC concept is kind of a waste. That's where a control panel shines by using less real estate, lower cost etc.

"Alarming" etc. is no different one way or the other, no sure what your thoughts are on that. You can set up an alarm system trigger from an overload relay aux. contract, and/or an aux. contact on the contactor, in conjunction with whatever your control system situation is that calls for a motor to run. That's a totally separate issue.