Initial Power-up of an Electrical Enclosure 1

[dkgreig]

I am currently tryin to find any information explaining the proper steps someone should take to inspect an electrical control panel before applying power for the first time. I'm mainly interested in what should or shouldn't be tested. What tools should be used (megohmmeter, ohmmeter, etc.). I've been reading some information on arc-flash evaluations, but it seems to be more directed towards equipment that's already in place.

Any information regarding standard practices, tips, or personal experiences would be helpful.

 

[jrs50125]

Before becoming an engineer, I spent several years as an electrical tech.. Needless to say I've seen my share of failed startups. My first bit of advice is to ohm check everything, verifying the wiring to the print. When that's done and you’re ready for startup. Stand back, look away, and be ready to shut power off immediately.

Good Luck

 

[gcaudill]

In my startups I've found the most comforting action is to close and lock the panel doors, clear the room, and throw the big switch. Common sense checks prior to powering up should be done, of course.

 

[Skogsgurra]

My "biggest bangs" have happened when I trusted people too much. DO NOT TRUST ANYONE! Check everything yourself.

High power cables and bus-bars are to be checked with a Megger using the right voltage. Disconnect anything electronic first to avoid damage.

Then make sure that the right voltages go to the right places. Hundreds of volts AC is not good for 24 V DC circuits. DC voltage is no good for AC loads like transformers and contactor coils. It is a lot of job doing these checks - but it pays to do them.

Test all I/O.

Check protections and set them according to motor ratings. Tick off everything in the diagram.

After this is done; apply voltage to the control circuits and "dry swim". Check sequences as much as dry swimming will allow and use jumers or a battery box to simulate process signals (if you use jumpers, use a contrasting colour - orange is good - so that you do not forget them after test is done). Correct any problems before continuing to "Live Show".

Check that motors are bolted down. That couplings are correctly installed. Universal joints are a special problem; Inner "crutches" shall be in the same plane, not 90 degrees!

Inspect the plant/machine and make sure that no people are in dangerous places. And that they stay outside untill you have done testing.

The live show should then not be much more than a routine test of all circuits and functions. Test all emergency stops first! Keeping doors shut and people away from the scene is always good.

And, make sure that you know where the main switch is. Where the first aid stuff is - and how to get an ambulance on site. You will very seldom need this knowledge, but when you need it - you shall have it.

Gunnar Englund

http://www.gke.org

 

[OperaHouse]

I'd like to think we can all do better than "throw the switch and run." One nifty device is the odinary electrical lamp. This is a non linear resistance that has a ten times increase in resistance when hot. I always use one to to check the phasing of transformers before applying full power. Figure a 100W lamp is good for about a half amp. Put them in parallel for more current and in series for more voltage. Most panel controls will still operate on slightly reduced voltages. A lamp glowing brightly will indicate a fault without doing any damage. Makes troubleshooting a lot easier. Disconnect higher current devices like motor drives till the basic circuits are checked.