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Guest123

Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

The machine could rotate in the wrong direction.
 

stef

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Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

hi guys,

What would the effect of incorrect phase sequence to the 5kw machine in a workshop be?

thanks

magpie
Pends what machine, if it has an intelligent inverter then it might not work at all. If if is a simple DOL motor the it would do what Lenny said. A pump would blow instead of suck, a drill would spin in reverse etc.
 
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paulthemagpie

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Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

so parts of the machine could go in the wrong direction, which could lead to all other types of problems

for example further damaging on the machine, damage to products on the machine, ect
 

trev

Regular EF Member
Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

What could happen to a motor trying to go the wrong way but being unable to? Eg a car lift in a garage is sitting on the ground, you press the go button and it tries to lower instead of raise.
 

stef

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Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

Not to mention Helf and Saifti like comonents flying through the work shop, end stops snapping off, electrodes short circuiting, well the list is endless. If it is a new machine test phase rotation on a less critical part first, such as a coolant pump. All other motors should be commissioned to the same phase rotation.
 

malcolmsanford

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Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

What could happen to a motor trying to go the wrong way but being unable to? Eg a car lift in a garage is sitting on the ground, you press the go button and it tries to lower instead of raise.
Marvelous things limit switches Trev ...............................
 
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Knobhead

Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

Well if your using a car lift as an example. Reverse the phase rotation and see what happens with the limits :tongue3:
 

johnboy6083

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Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

Pends what machine, if it has an intelligent inverter then it might not work at all. If if is a simple DOL motor the it would do what Lenny said. A pump would blow instead of suck, a drill would spin in reverse etc.

beleive it or not, but pumps still pump, when the phases are reversed. They dont like it, and the flow is reduced, but they work. When installing smaller pumps which dont require a coupling of the motor shaft to the pump shaft, you should operate the pump with the phases both ways round. the pump will draw less current the right way round, and the flow will be increased, along with the pressure.
 

snowhead

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Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

Dammit Malcolm why did you remind him about them man, I was working up to them:)
Surely the phase to the switch will now be reversed and the switch will work the other way round...
 

CSEE

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Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

It all depends on what the 5kw machine in question was Paul. i am guessing you have wired something the incorrect way? and client is claiming some major damage has been caused???
If it is a machine with a gearbox or a vane pump then severe damage can happen by a few seconds of running.
need to know more details to be able to really say.
Regards Darren
 

sparks1973

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Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

some gearboxes are very liable to damage from thrust forces placed on em by rotation in the wrong direction....so a polarity reverse could be a very expensive mistake....
 

Guitarist

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Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

some gearboxes are very liable to damage from thrust forces placed on em by rotation in the wrong direction....so a polarity reverse could be a very expensive mistake....
I was watching a program the other night on polarity reversal. Apparently it's imminent, and for a while we will have no magnetic field to stop the nasty solar winds....
 

nickblake

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Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

Did know of an incorrectly phased methain burner fan at a refuse tip it was sucking in the flame instead of blowing could have blown the whole island up lol opp's
 

PEG

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Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

.....and a planing machine in a joinery workshop sends out thicker timber than you put in....:jester:
 

Philpot

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Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

The important thing is to carry out a full "FUNCTIONAL TEST". It is easy for to get the motor running in the correct direction but have all the FWD and REV limit switches swapped over. This can be extremely dangerous as things like the limit switches will not work( as previously mentioned).

This usually happens if the motor is connected the wrong way round and then as it is possibly more difficult to access the direction is corrected at the fuse board. It may have been done the wrong way before you even started working on the machine so beware.
Interesting about centrifugal pumps actually pumping even though they are running in reverse.
 

Guitarist

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Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

I have known installations wired incorrectly, only to find that the electrician on site has swapped 2 of the phases over on EVERY piece of equipment to get it right, rather than go back to the supply.
 
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Knobhead

Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

I have known installations wired incorrectly, only to find that the electrician on site has swapped 2 of the phases over on EVERY piece of equipment to get it right, rather than go back to the supply.
I made a contracting firm reverse the direction of 120 motors. Pity I’d forgotten to tell them the entire works had reverse rotation
 

Archy Styrigg

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Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

I made a contracting firm reverse the direction of 120 motors. Pity I’d forgotten to tell them the entire works had reverse rotation
You've got a naughty streak in you! :wink_smile:
 

Guitarist

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Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

I made a contracting firm reverse the direction of 120 motors. Pity I’d forgotten to tell them the entire works had reverse rotation
I bet your name was used in some colourful ways....
 
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Knobhead

Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

We were installing 11 MCC's, the 120 motors was off the first to be installed. They wanted to reverse the 600A incomer to that one panel only, NO WAY!
 

Guitarist

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Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

For anyone interested in some unrelated trivia, the milk used to be put in before the tea and sugar to prevent the hot tea from cracking the cheap crockery :)
 

ipf

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Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

For anyone interested in some unrelated trivia, the milk used to be put in before the tea and sugar to prevent the hot tea from cracking the cheap crockery :)
So that's why me oxo used to spontaneously combust....
 
K

Knobhead

Re: Wha would the effect of incorrect phase sequence to the 5kw machine in a workshop

Tea then hot water, allow to brew. 1/2 teaspoon of sugar, NO milk!

Got to be Yorkshire hard water tea, it's the best.
 
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