3 Phase Balancing 3

[Erick D]

Working on my first panel for controlling 5 Water pumps 208 VAC @ 16A each, 5 generators 208 VAC @ 15 A each, 5 Generators 208 VAC @ 6A each. 5 water pumps 120 VAC at 10A each.

I am doing my best to balance my voltage source Y-connected 208 Vll (120Vln) @ 100A per phase.

For the most part the system is design to be on at the same time (thus trying to balance the load) but there could be times were one the generators is not on or a pump not running. And even if all the loads are on I am seeing one of the phases having 16 A less than the other 2.

How important is to actually have all 3 phases balanced and how much can I get away with? In school they teach you how important it is to balance the load but unfortunately I can’t just divide my load by 3 and hook it up like I used to do in HW.

Thank you very much in advanced.

 

[davidbeach]

11 generators? Are you crazy?

 

[itsmoked]

5 Generators 208 VAC @ 6A each

Really? Only 6A?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

The phase balance is OK but that is the least of your worries.
The cost of the equipment to parallel and match voltage with changing loads on all those generators will be much more than the cost of one properly sized generator.
Shall we tell him or just let him find out that those 16 Amp pumps will need 40 to 50 Amps to start?

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[itsmoked]

Probably should tell him..

Erick D; You will need more than just the pump full rated current to start them.

You would do yourself a big favor by sketching out a one-line drawing of your proposed scheme and let us vet it for you.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Erick D]

Apologize for the delay. Took me a bit to come up with an schematic please see attached.

 

[itsmoked]

Here's a direct post. The link provided by the OP is much higher resolution.

HAHAHAHA!! I'm so glad you've included a drawing that's nicely labeled. This is an electrical engineering forum so when you say generator without any further info it is not assumed to be an "ultrasonic generator".

I would not worry about any imbalancing with regards to this design. You've set it up balanced and it will typically be pretty balanced and that is good enough.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[waross]

Just a little misunderstanding.
In this forum, when you say generators, this is what we visualize:

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Erick D]

@Keith and Bill truly apologize for the miss understanding. It was dumb of me to use the term Generator loosely (now looking back I would have been just as confused if someone else had as me that).

At the end of the day my question was how balanced do the cure to phases need to be? When I add all phase currents phase A is about 69A, phase B is about 70 A and Phase C is about 73 A. Is this something that in practice it’s ok?

Thank you very much.

 

[davidbeach]

That’s extremely well balanced. Glad to see that you’re not as insane as your original question suggested.

 

[Erick D]

Thank you all very much for the help!

 

[waross]

A little tip that may save you a lot of confusion if you ever encounter it:
When adding up your loads, you can often take a numerical sum but not always.
Currents are directed quantities.
If your loads have differing power factors The directed sum will be less than the arithmetic sum.
When adding line to neutral loads with line to line loads you must consider the phase angle between them as well as the power factor.
A 10 Amp load from A to B and a 10 Amp load from B to C will result in 17.3 Amps on line B.
That's with equal power factors.
Don't worry about it too much, but when your measured Amps don't add up, think;
"Phase angle."

Bill
--------------------
"Why not the best?"
Jimmy Carter