A BAD PUMP,A BAD CONTROL BOX OR BOTH?

[Reach4]

New one for me.

I think the system horacio and valveman describe is the corner grounded delta. http://en.wikipedia.org/wiki/High-leg_delta s describes high leg delta with midpoint of one winding grounded.

 

[DonL]

It is cool that Forum members teach electronics 101 now.

Rock On.

 

[Sponsor]

 

[horacio]

Our 3 phase has the same kind of thing here. We call that one a "wild leg" or "high leg", it has a grounded L2. Checking between L1/L2, L2/L3, and L1/L3 you get a balanced 230 volt 3 phase. We just have to be sure and not pull off the "wild leg" to wire up anything single phase.

Thanks for your info because I was worrried about buying a motor for a different kind of voltage. Most people think that 3 phase is composed of
3 lines of 120 volts each.

 

[Valveman]

I was waiting for DonL to explain it, he must be getting old like me.

Motor companies had rather have true three phase with three transformers, but you are good to go. We do it all the time.

 

[horacio]

New one for me.

I think the system horacio and valveman describe is the corner grounded delta. http://en.wikipedia.org/wiki/High-leg_delta s describes high leg delta with midpoint of one winding grounded.

Thanks a lot for the schematics,that takes me another worry away,I was thinking that maybe the hot leg was conected to an specific wire on the pump motor but I can see now that is no the case,I only have to do a test check for the correct rotation before installing the pump,that is instructed
on Franklin literature. your help is appreciated. Thanks again

 

[horacio]

It is cool that Forum members teach electronics 101 now.

Rock On.

You are correct knowledge from experience is the best knowledge that we can adquire. Best regards

 

[DonL]

I was waiting for DonL to explain it, he must be getting old like me.

Motor companies had rather have true three phase with three transformers, but you are good to go. We do it all the time.

I am getting old. You got that right.

If you can shift the phase 120 Degrees you can get any motor to work.

You shift the phase 360 degrees and it is a no go.

Well unless it is a DC motor, Then it runs backward.

 

[DonL]

You are correct knowledge from experience is the best knowledge that we can adquire. Best regards

73 to you also.

Got to love the forums.

Just use a fuse and all is good, For the most part. PPE is good also.

 

[Ballvalve]

Thanks Valveman. By the way ,my CSV1A was shipped to me today,later on I will ask some queations to you about its installation,will like to get familiar with the issue before get to me in Costa Rica,at least 2 months from now.
I was here looking for you to ask about the 3 phase standard there,here we have 2 lines of 120 volts and one line of 180 volts,called by the electricians
high line or start line. I want to know before I buy a 3 phase Franklin pump motor if that voltage is correct. I also found this morning that Franklin
motors are now made in Mexico,kind of discourage news to me,quality is in doubt,hope I am wrong with my personal opinion. I feel bad. THANKS

I have the "fake" 3 phase on my property. It is done with just 2 transformers, and I have two lines 120v and then 240 between them. The third line, 'stinger' line is @210v to ground. It varies by country. This type of 3 phase should only start motors about 15 HP in size. This I saw proven at my shop when we had big production and too many motors started by chance - Transformer blew up and created quite a fire event. 'Real' 3 phase has 3 transformers and usually comes in at 400+ volts and one must have a stepdown transformer to obtain 120/240 circuits. Only for very large production.

Bad news that Franklin has sold it's soul for cheap labor. But I suppose the quality remains high. They still make larger motors in the USA.

I am wondering where Grunfos makes its smaller well pumps and motors. We have a Grunfos Mfg. plant near here, they were making circulator pumps. I suppose it is a combination of many countries parts and labor.

 

[DonL]

'Real' 3 phase transformers have all of the windings phased properly and only 1 transformer Core is required.

Phase gets tricky on 3 phase stuff. Phasing 3 transformers together is even more tricky.

The 3 phase 600 Volt stuff will make some power, and is used when you need to make a bunch of oil.

 

[Ballvalve]

I was waiting for DonL to explain it, he must be getting old like me.

Motor companies had rather have true three phase with three transformers, but you are good to go. We do it all the time.

Open delta is the budget 3 phase with the 2 transformers. And its the best if you don't need to start much more than a 15 hp motor at one time. You can start larger motors with soft start. And you get the bonus of 120/240 volts if you get the correct 2 wires, as you noted [some only give you 208 volts, I suspect that is what the gentleman in Costa Rico has]

Delta, the 3 transformer system has to, at least here, come to you at a voltage over 400, and then you must buy a step down unit to get standard power. Either system is amazing in its gift of being able to use tiny wires for huge motors. When you get into the 600 volt range, the wire savings is immense. Europe is quite smart in having only 240 volts in the house. The American copper companies would be very sad to make 18 and 16 gauge Romex! There go the profits and the mines.

Capacitor run motor control boxes give single phase a little more of the flavor of 3 phase. Seems they all should be made so.

 

[DonL]

Capacitor run motor control boxes give single phase a little more of the flavor of 3 phase. Seems they all should be made so.

That sounds like something you put on your tongue to test.

Kind of like a 9V battery.

It takes big run caps to run much power. Once the motor is running, there is no need for them.

Especially on a fix frequency motor.

I think those in well windups run on AC converted to DC.


Have Fun.

 

[horacio]

Open delta is the budget 3 phase with the 2 transformers. And its the best if you don't need to start much more than a 15 hp motor at one time. You can start larger motors with soft start. And you get the bonus of 120/240 volts if you get the correct 2 wires, as you noted [some only give you 208 volts, I suspect that is what the gentleman in Costa Rico has]

Delta, the 3 transformer system has to, at least here, come to you at a voltage over 400, and then you must buy a step down unit to get standard power. Either system is amazing in its gift of being able to use tiny wires for huge motors. When you get into the 600 volt range, the wire savings is immense. Europe is quite smart in having only 240 volts in the house. The American copper companies would be very sad to make 18 and 16 gauge Romex! There go the profits and the mines.

Capacitor run motor control boxes give single phase a little more of the flavor of 3 phase. Seems they all should be made so.

What I have here in Costa Rica is 2 transformers at the pole, with an imput of 12000 volts,one step dow to 2 lines of 120 volts and the
other step down one line of 180 volts. Oe ene thing also is that the 2 transformers are fed by two different 12000 volts primary lines.
A worker from the power company told me you can not get 3 phase feeding the two transformers from the same primary (high voltage) line.
There are also here 2 other primary lines of 18000 volts to feed transfromers with 440 volts 3 phase for industrial customers.

 

[Ballvalve]

Just curious - do you have 208 volts or 240 volts with your 3 phase? I don't have any 3 phase well motors but suppose they are rated for either voltage.

 

[horacio]

Just curious - do you have 208 volts or 240 volts with your 3 phase? I don't have any 3 phase well motors but suppose they are rated for either voltage.

I do have 2 lines of 120 volts and one line of 180 volts,still bothers me why this line of 180 volts instead another one of 120 volts unless
maybe on some cases this line is used to start the motor. here is called the high line or starting line,in the U.S is called the HOT LEG.
I ordered the pump from a Florida dealer( Grundfos 2HP,230 volts,3 phase) and can not give more info till I have it conected,maybe in 3 months
from now. Is coming to C.R via ocean cargo and takes long time to get here. Someone says my confuguration will balance to about 130 volts
between lines and maybe is why this pump is specified for 230 volts-3 phase operation.

 

[horacio]

I was waiting for DonL to explain it, he must be getting old like me.

Motor companies had rather have true three phase with three transformers, but you are good to go. We do it all the time.

Valveman one question please. I ordered the Grundfos 2HP,3 phase-230 volts pumps.
Instructions tells you how to do phase balance,a clear procedure. But what you do if in the lower disbalance conections set up the
motor runs in the wrong direction. The pump is coming ocean cargo and will take some time to get here from Florida but I like to
get the most familiar with the 3 phase conections. I have a 10 hp,3 phase air compressor but I bought it used and came with the the
switches wired,been running for more than 12 years and never ever have had any trouble with. So please help me again.TKS

 

[Reach4]

You have 3 hot lines, right? Measure your 3 hot-to-hot voltages with your voltmeter.

If a 3 phase motor runs backwards, reverse 2 of the hots.

 

[horacio]

You have 3 hot lines, right? Measure your 3 hot-to-hot voltages with your voltmeter.

If a 3 phase motor runs backwards, reverse 2 of the hots.

Thanks for your answer. being unfamiliar with 3 phase conections my best thing to do is find an electritician with a 3 phase sequence tester to
do the job for me,seems to me that is the best aproach to the problem, I wold hate to buy the tester because this is not my work line and
I already have more junk around that needed. Thanks.

 

[Valveman]

You don't need a tester to set the proper rotation on a 3 phase pump. You have a 50/50 chance of getting it right the first time. It doesn't hurt a pump to run backwards for a while. The problem is they will pump quite a bit of water running backwards. I have seen some that have run that way for years and the owners didn't know. But when you switch T1 and T2 they pump a lot more water and pressure when running in the right direction. Just try it both ways and you will see that one way pumps much more water than the other, and you will know you have the right direction.

 

[DonL]

One way you can test three phase is to use 3 light bulbs, and they should all be the same brightness.

You can see ground faults too.

I recommend PPE for any smoke test.