oper delta connections and limitations

1. In general it is not a good idea to have a 3 ph delta system underground, whether it is open delta or closed delta. I would stick to an overhead supply.

2. A 200 hp motor is pretty large to operate off an open delta. Your transformers are big enough, but you may still have trouble starting the motor.

Thanks you for your input. Would a VFD help in the starting?

I am not sure that the VFD would help. I don't have enough direct experience with VFD's for this type of application. My time was mostly as an engineer with a large electric utility. For a motor this big we would have wanted to add the third phase to close the delta. Does your utility company have an industrial representative that could advise you on this? Call them and see what they say.

My Friend,

Using VFD or VSD is possible for 200hp/LV. But, using it for well pump? It is very expensive.

We are not recommending using VFD/VSD to well pump due to its cost. Just use "reduced voltage" controller only.

But, if your company is well off in expending, Yes, you can use it. Contact yout nearest supplier(s) for more details.

Eren

My Friend,

Please state the present situation of your 3ph/open-delta feeder line?

* Are you in the middle of designing it?

* Or, you will make some pre-engineering to the existing installation?

Eren

Thanks for your intrest.

We are looking at all options including a gen set. That being said

let me start out by saying the well pump will be at aprox. 3200 feet down the hole. We are using a CentraLift pump from Baker Hughes. It is a positive displacement pump.

The idea of a VFD is to soft start, taking off the initial surge. Reason being the available power comming down the line. It is and has been spotty even before we started this project.

AS far as cost of initial set up as with the VFD, that pales compared to the cost of drilling the well so I am not worried about it. I am trying to find the best, most economical, maintenance "free: option.

The 167 x-mfr(s) would be located in close proximity to the well head.

My Friend,

In your statement, you are doing pre-engineered solution. Right? There is no easy solution on this, please see below:

Some querries:

1. Do the well pump is for what? Water or oil?

2. The depth (3200') you have mentioned is almost 1000M down below?

3. The rated capacity of your well pump is 200HP?

4. The power supply sometimes fluctuating?

Recommendations:

Per NEC/IEEE requirements and electrical engineering design standards, the following should be:

* for all 200HP and above should be medium voltage (MV) power supply.

* Due to the depth of well head is 3200 feet, the MV power supply is the best.

The 230/380VAC is not enough, especially during starting, you will have a big voltage dip.

Even you change the previous motor controller to VFD, it will be erratic due to fluctuating power supply.

You can not solve your problem as easy as you think. You need thorough study of the system. And prepare budget to CAPEX not OPEX for the next year.

Good Luck.

Eren

If you need a help to solve this, try to contact me. My email address: eduarte.eren@gmail.com