Using Breakers to control motors

[weressl]

In the process of building our new plant we have many 480V starters that have solid state overloads. When we want to bump motors for the first time to verify direction, it is sometimes difficult to do without having the overloads programmed b/c the output on the overload will not close until the overload is programmed. A lot of times these motors need to be bumped before these overloads are programmed in order to verify direction.

To bypass the overloads the electricians in the field are taking the 120V control voltage and wiring it directly to the contactor coil. They are then using the 480V breaker associated with each starter to turn on the motor.

I know this is a blatent code violation but many in the field are claiming that this practice is o.k. for just temporary turning on of motors such as the bumping I described.

What are others thoughts on this temporary measure of using a breaker for controling a motor? My argument is that these breakers are not designed for such activity and should not be used as such even temporarily. What potential negatives are involved with doing this?

There is a contradiction in what you describing. If the electricians connect 115VAC in the field to the starting circuit, why would you use the corcuit breaker to turn the power ON/OFF? You would only need to jumper the OL and/or other interlock circuits.

Sounds like a scheduling problem to me. I would NOT work around somebody else's mistake and take electrical risks both for safety and equipment damage potential.

What if the CB contacts weld shut?
What if there is a short circuit, a ground fault?
What of the driven equipment is jammed?
What if the radio communication breaks down and the equipment in the field is flying apart and the operator is unable to confirm that the CB can be shut off?
Why NOT test the equipment and installation fully at commissioning time?

 

[mayanees]

There is a contradiction in what you describing. If the electricians connect 115VAC in the field to the starting circuit, why would you use the corcuit breaker to turn the power ON/OFF? You would only need to jumper the OL and/or other interlock circuits.

Jeez, I missed the part where they're turning on the 480V MCP/breaker to start the motor.

What's logical to me is that the starter is energized through the MCP or CB, at which point the coil is energized briefly, thereby pulling in the M contactor, and then turned off. Someone witnesses motor rotation.

I would never advocate closing in manually on the starter using the MCP or CB.

John M

 

[Cold Fusion]

I would never advocate closing in manually on the starter using the MCP or CB.

John -
I'm right with you.

But I'd be lying if I said I had never bumped motors using the CB and sometime even pushing in the contactor manually. In previous lives, when I was the one pulling the wire, making the connections, and doing the commissioning this was pretty normal. Meg the conductors and motor, pull the pump coupling, bump the motor.

I interpret 70E as this being a haz cat 1 procedure- FR shirt, blue jeans, hard hat, safety glasses. I don't see the risk as having changed - but the social climate has. So, I'm with you - wire a button.

cf

 

[mayanees]

John -
I'm right with you.

But I'd be lying if I said I had never bumped motors using the CB and sometime even pushing in the contactor manually. In previous lives, when I was the one pulling the wire, making the connections, and doing the commissioning this was pretty normal. Meg the conductors and motor, pull the pump coupling, bump the motor.

cf

DITTO CF....

I think back to my the late 80s when I had responsibility for the electrical system at an industrial plant. I heard a buzzing in the back of some 12,470V gear. Well, in days of old, I thought nothing of opening up the back of the gear, of course while energized, and then parading anybody who was interested in to see the tracking across a termination!
It took the Arc Flash craze to calm this cowboy down!
John M

 

[Cold Fusion]

DITTO CF....

I think back to my the late 80s when I had responsibility for the electrical system at an industrial plant. I heard a buzzing in the back of some 12,470V gear. Well, in days of old, I thought nothing of opening up the back of the gear, of course while energized, and then parading anybody who was interested in to see the tracking across a termination!
It took the Arc Flash craze to calm this cowboy down!
John M

For this case, I'm nowhere near what you are describing. Bumping the motor under the protrayed conditions appears to be a haz cat 1 job. The risk is way low.

The social climate has changed the perception of the risk.

For example: (Laszlo, I'm not picking on you , your post was just a convenient list)

What if the CB contacts weld shut?
See Jim's post 13
What if there is a short circuit, a ground fault?
That's what the CB is for
What of the driven equipment is jammed?
That's why one removes the coupling or hand rotates
What if the radio communication breaks down and the equipment in the field is flying apart and the operator is unable to confirm that the CB can be shut off?
Definition of "bump" is on-off
Why NOT test the equipment and installation fully at commissioning time?
I don't know - what do the scope and specs say?

None of this changes my previous comment. Considering the perception of risk under todays social climate, put in the button.

cf

 

[zog]

I interpret 70E as this being a haz cat 1 procedure- FR shirt, blue jeans, hard hat, safety glasses. I don't see the risk as having changed - but the social climate has. So, I'm with you - wire a button.

cf

FYI, the PPE requirements for HRC 1 has changed.

 

[weressl]

For this case, I'm nowhere near what you are describing. Bumping the motor under the protrayed conditions appears to be a haz cat 1 job. The risk is way low.

The social climate has changed the perception of the risk.

For example: (Laszlo, I'm not picking on you , your post was just a convenient list)

What if the CB contacts weld shut?
See Jim's post 13
See next
What if there is a short circuit, a ground fault?
That's what the CB is for
No, the CB is for protection against accidentally occuring faults. If your answer would have been: tested before, that's fine.
What of the driven equipment is jammed?
That's why one removes the coupling or hand rotates
Did you see it anywhere that it is the precondition of the test?
What if the radio communication breaks down and the equipment in the field is flying apart and the operator is unable to confirm that the CB can be shut off?
Definition of "bump" is on-off
Could you point to me where that defintion exist? In practice, they turn on the circuit and shut it off when the rotation is verified.
Why NOT test the equipment and installation fully at commissioning time?
I don't know - what do the scope and specs say?
Neither of us know. I cited what it should say and what normal startup procedure is.

None of this changes my previous comment. Considering the perception of risk under todays social climate, put in the button.

cf

My point was to avoid short cuts and resist people trying to push you into it. I may exhibit disproportionate vigor in objecting, but I have seen it how it happens. One little deviation from good practice leads to becoming THE practice, leads to other deviations and eventually leads to the breakdown of the system. We should resist tinkering and toying with electrical work.

 

[Cold Fusion]

What of the driven equipment is jammed?
That's why one removes the coupling or hand rotates
Did you see it anywhere that it is the precondition of the test?
.

post 6

cf