Commissioning

I'm relatively new to PLC project work, so please excuse my ignorance.

When commisioning, what events occur, and in what order.

I assume that firstly comes the IO checks.

Assuming that the electrical safety checks have been done and the correct supplies are available.

1. Isolate all of the outputs that may cause a hazard if they turn on. Such as switching off motor MCBs etc.

2. THEN TEST THE EMERGENCY STOPS AND THE GUARD INTERLOCKS

3. Test the inputs with the outputs isolated - ABs have a test mode that will run a program but with no physical outputs.

4. Again ensuring that nothing dangerous will operate, test the outputs by forcing them on from the PLC.

5. with the outputs STILL DISCONNECTED, start testing the various functions, I write programs so that I can turn off modules and test them in isolation. So test your I/O modules first and then start adding in each of your functions until each module has been tested only with the other modules it needs to function.

6. Start adding in modules until the whole program and machine has been tested together.

7. Finally re-connect the outputs and try it with the real machine on the end - this is where you find that it doesn't actually work like you thought it would.

8. Go back as far as you need to and do it all again.

Good luck - I accept no liability for any outcome from the content of this message, readers are responsible for ensuring the safe conduct of any commissioning work they undertake.

No way, never allowed the time for this,

4" x 4" x 4' length of timber to turn on isolator & subsequent MCB's its always a blast to see how the machine interpets the c~#p you wrote/programmed & hookup...............

Just for fun of course

best to be drunk on the job than off it

Actually, one tip that is in line with Mylo's is you should never stand directly in front of an MCC or starter or VFD the first time the breaker is thrown and the unit powered up. Always stand to the side, and away from the hinged side. You only need to see the smoke released from one medium voltage starter to understand why.

One item I'll add to John's list is to make sure you test the system at it's operating limits and during any malfunction scenario you can come up with, all within the limits of safety, of course. It is much simpler to write logic that works when the machinery is running fine than it is to write logic that works when Murphy's Law kicks in.

Always stand to the side, and away from the hinged side

Click to expand...

Tom,

About all the High Voltage guys I've ever worked with say to
stand on the side of the hinge. They always say they would much prefer to get blasted
away from the door than to be in the way of the arc flash.. Please forgive me if I mis-understood your reply.

Gary

GMc said:

Tom,

About all the High Voltage guys I've ever worked with say to
stand on the side of the hinge. They always say they would much prefer to get blasted
away from the door than to be in the way of the arc flash.. Please forgive me if I mis-understood your reply.

Gary

Click to expand...

I've always heard stand to the non-hinge side, ie switch with your left hand, arm extended out as far as possible (assuming switch on right side of box).

Most MCCs I've worked with have the hinge on the left side and the disconnect on the right side. So to stand on the left and operate the disconnect you would be reaching across the door. I wouldn't recommend that.

The procedure I've been taught is:
Stand to the right of the bucket.
Operate the disconnect with your left hand.
Turn away from the bucket as you close the disconnect.

I agree with Mellis, but I don't work with any high voltage stuff. 4160 motors are high enough for me, and I always get an electrician for that.

The problem with standing on the hinge side is that you are likely to get an arm or nose broken if the door flies open. Standing on the breaker non-hinge side with your arm extended to it's fullest and your face turned away should keep you out of the arc blast for low and medium voltage stuff.

One addtion to Tom's statement,ALWAYS WEAR A FACE SHIELD AND AT LEAST ELBOW LENGHT GLOVES!!!!!!!
Regards,
Tom B,

Tom,

First of all 4160 is surely not low or medium voltage but anyways…

One should not associate arc flash DANGER solely with voltage. Energy = Voltage x Current x Time. So it is possible for the arc flash energy level on a measly 480v (compared to 4160) equipment to be as high or higher than on 4160V or 15KV equipment.

As far as a broken nose, no, you turn your head away like you mentioned.

As far as a broken arm, yeah maybe… I would much prefer that than my
skin dripping off my arm.

Mellis,

Whoever is teaching you surely isn’t doing you any favors…


Gary

From my military training ( a LONG time ago !!)

Stand on NON-hinged side

Operated disconnect with the arm that will allow you to face away from the enclosure.

Turn head away when making contact...

NEVER, NEVER, NEVER reach across the enclosure to operate the lever...

Again, this was MY training... yours may differ.

Jim

Well, Gary ole pardner, I'm willin' t' let you close breakers yer way, and I'll do it my way. They is advantages and disadvantages t' both I reckon, and I ain't no expurt.

Now, as fer as low and high, if'n ya stick yer finger in it 120 kin feel like high voltage, and I agrees 4160 sounds like high voltage to us fellers whut routinely use 24 VDC. How-some-ever, to motor control fellers anything 600 VAC and below is low voltage. 2200 and 4160 is medium voltage. The definition as to whut is high voltage ain't entirely clear but it generally refers t' transmission line levels and is usually considered well above 4160.

Here is a quote:
"In the U.S., the National Electric Code defines HV as 6,001 V and up—with a lower 601-6,000 V range designated as 'medium voltage.' Europe uses different designations. Institution of Electrical and Electronic Engineers' (IEEE) Std. 100 defines HV for electric power systems as 100 kV or greater, ranging up to 230 kV. An extra-high voltage (EHV) class follows above 230 kV. For power cables, still other ranges are specified in IEEE Std. 100."


from this article:
http://www.manufacturing.net/ctl/article/CA478480?text=medium+voltage

I think I can see where Gary is coming from.

First, realize that the door of the enclosure has a primary latch due to the handle mechanism and a secondary latch due to the interlock with the breaker actuator.

Consider what could happen following a blow-up of a breaker.

1. The energy released is entirely contained within the enclosure.
2. The energy released blows the door open.
3. The energy released overcomes the primary latch, but the secondary latch holds. In this scenario, the door ends up partially open.
4. The primary latch holds, but the door is deformed enough so that energy is released from the enclosure.

In scenario 1, it doesn't matter where you're standing.
In scenario 2, the energy released is going to come straight out of the enclosure, but the door is going to try to take your arm off, so you're safer standing to the right.
In scenario 3 and 4, the energy released from the enclosure is going to be aimed to the right of the enclosure, so you're safer standing on the hinged side.

So, what's the most likely mode of failure? There is no one place that's the safest regardless of what happens.

mellis said:

Most MCCs I've worked with have the hinge on the left side and the disconnect on the right side. So to stand on the left and operate the disconnect you would be reaching across the door. I wouldn't recommend that.

The procedure I've been taught is:
Stand to the right of the bucket.
Operate the disconnect with your left hand.
Turn away from the bucket as you close the disconnect.

Click to expand...

Originally posted by GMc
Mellis,

Whoever is teaching you surely isn’t doing you any favors…

Click to expand...

What is wrong with what he was taught?
Most standard disconnect handles are mounted to the right of the enclosure. If so that is the right way to do it.
If the handle is on the left side you stand to the left and use your right hand to engage it.
As stated you never want to reach across the door.
Face shields and hot gloves should be worn but rarely are.

I think if you wore face shields and gloves, like you're supposed to, people would as "What's that fer?"