Motor Control Center Inspections

Look for a manufacturer's name plate on the MCC. Some manufacturer's will list a purchase Order number, or serial number on the nameplate. If that information is listed, you should be able to contact the manufacturer and request the schematics for the MCC as it was built.

Mariner

I am a manufacturer of MCC in India.Generally I maintain record (drawings) of all MCCs I have supplied to my customers.

As suggested by others ,you may note down the details of the source and try to get all the detailed drawings and other relavant documents.

Even otherwise ,there is no problem in building up the relavent details, but it will be time consuming and cumbersome.

You may have to get basic details like motor capacity,(rating),method of starting,any sequential starting involved,any interlocking involved,any communications to other devices involved etc.

For typical ratings, components list with ratings and specifications to be taken from the existing MCCs.

Schematic drawings may not be required if the starters are simple, since any way you are going to build up new MCCs for replacement.

Should you require any assistance please contact.

Once you have the as-installed information, your challenge will be tracing changes that have been made -- especially to the wiring -- since installation.

The replies that you have are pretty much on target. You don't mention the brand MCC. I am familiar with the Allen-Bradley brand and they have a metal serial number plate attached to the vertical wireway door. With the serial number off that plate, they should be able to provide as-built information for you. Also, many of their product catalog numbers are "smart" numbers and can be decoded with their literature. Finally, if you have to do this project manually, they have a pretty generic MCC checklist that you should be able to download and use it for any brand MCC. Its called the CENTERLINE 2100 Motor Control Center Specification Checklist

http://literature.rockwellautomation.com/idc/groups/literature/documents/sr/2100-sr003_-en-p.pdf

If the equipment supplied by the MCC has external control circuits, those circuits are likely not on any factory drawings you may receive. The control circuits are usually designed by an in-house or consulting engineer. Also, if the MCC has been in use for several years, modifications may have been made since the original installation. That information would also not be on the factory drawings.

In addition to getting any available factory drawings, I would recommend the following steps:

Create a worksheet for each starter and/or switch. The worksheet should include the items shown below. Fill in the worksheet based on a survey of the installed equipment, NOT on the drawings:

• power voltage & wiring (3 wire or 4 wire)
• power fuse size
• control voltage
• control fuse size
• CPT capacity
• load size (motor horsepower, etc.)
• control station locations
• control station design (pushbutton, maintaining switch contacts, PLC, etc.)
• control interlocks

Note the entry location for each set of power cables and control cables. Ensure that the specification for the replacement MCC allows cable entry in the same locations.

Also note the location of each specific starter. Unless you want to pull in all new wire (or do massive amounts of splicing), you'll want the new MCC buckets to be as close as possible to location of the old ones.

Compare the information on your worksheets with the factory drawings and your own common sense. I would also suggest talking to the operators who actually use the equipment on a daily basis. They may be aware of "below the radar" control modifications, made for ease of operation or personal convenience, that don't appear on any document. For example: after a production line has been running for several years, maintenance installs "Jog" buttons next to all motors to allow for clearing jams or testing repairs. The addition never gets documented.

With the worksheet information, you should be able to draw your own schematic for each starter. Most MCC manufacturers have generic schematics for their equipment available on the internet, and they can be downloaded in AutoCad .DXF format. Using that as a template, you should be able to create a your own schematics in short order.

Please maintain a softcopy of the MCC in your company.

Maintain an excel sheet which gives you details like

1. Machine no.

2 Type no. or order no. of the manufacturer

3 Rating

4 Manufacturer name

5 Date of change

6 Details of new modification

7 Reason of modification.

8 Lesson learnt

This would help you analyse the failure and remedies and also reduce future failures.