Quality work by a electrical trainee.....

[TJ Anderson]

Today on site, I bought in a couple of 12hp pumps, motors wired in star. They spun in reverse when I hooked them up to the generator fed supply, despite my knowing the configuration was correct and already tested in my workshop.

3 windings and a star point. With the phase rotation you had, configuration was incorrect for the rotor direction you wanted. A motor spinning the other way to what you want is still technically correct electrically......just not the way you wanted it . What he did Switching any 2 phases was the right thing to do.

 

[TJ Anderson]

But as a fairly mature spark he should have known it's correct to maintain correct phase to (in theory) make balancing calculable

A 3 phase motor is still a perfectly balanced load no matter what the direction, hence no neutral required.

 

[TJ Anderson]

So I conclude that the real problem is the selling of the courses, making it seem as if anyone that fancies a pay rise can have one in just a few weeks. In reality you either are right for a line of work or you are not.

Don't write yourself off to forever be unqualified, if you have the knowledge then get the quals anyway

 

[MFS Electrical]

How do you know it was someone who had done one of the Domestic Installer courses Matt?

This next bit isn't aimed at all towards you Matt, just in general....

I realise the above install is appalling but it would be nice if there was a bit of a balance between showing good work and bad work. I wonder why people like having a go at others so much, it's like the Jeremy Kyle of electrics sometimes!

Because honestly good work isn’t so entertaining

 

[SparkyChick]

I've never felt limited in what I can do by anything other than a safe knowledge of my own limitations.

That is what's controls me... I know and understand my limitations and am careful not to push too far outside them in one step.

 

[Deuce]

3 windings and a star point. With the phase rotation you had, configuration was incorrect for the rotor direction you wanted. A motor spinning the other way to what you want is still technically correct electrically......just not the way you wanted it . What he did Switching any 2 phases was the right thing to do.

Nope. I later checked another pump of mine on the same generator spinning correctly. The other two in reverse. All three spun correctly on the same feed at my workshop. There was a cable swapping the phases somewhere.

And really, the point was that I invited him over as I wasn't a spark, and he left me to modify the wiring of a 3ph pump!

 

[Deuce]

A 3 phase motor is still a perfectly balanced load no matter what the direction, hence no neutral required.

Yes but you're need to ensure phase conformity across the entire installation to have any hope of balancing overall. On this job there is no hope or control, so it's not really an issue anyway.

 

[TJ Anderson]

Yes but you're need to ensure phase conformity across the entire installation to have any hope of balancing overall. On this job there is no hope or control, so it's not really an issue anyway.

Not sure what you mean there?

The 3Ph motor is a balanced load, it cannot affect the phase balance of the install at all.

 

[Deuce]

Don't write yourself off to forever be unqualified, if you have the knowledge then get the quals anyway

I dont need to be. I always have a spark to hand in the field and nothing leaves my workshop without a consultation at the start of a design and a test at the end.

I'm also mindful of the fact that qualification would be pointless for me, as I don't do the work on a day to day basis, i would never be able to keep up with regulation the way you guys do. I'm perfectly happy to pay for the time of a good, bang up to date spark. I just checked on our accounts software what i spent on professional services last year - it turns out you all owe me a beer..

 

[Deuce]

Not sure what you mean there?

The 3Ph motor is a balanced load, it cannot affect the phase balance of the install at all.

I know. But the different rotation between motors fed from a single source shows that that along at least one cable/distro the phases were swapped. In theory phase continuity should be maintained from the power source, so that all equipment (not just my pumps) can be out on the phase that will equal the best balance overall. The fact one load is by nature perfectly balanced makes no difference to all the 1ph stuff they will connect to each line.