I am just new in the field and I have encountered a problem that I cannot think of anything to solve it.

We had installed 3 750Hp, 400V, Y-D Submersible pumps 1 kilometer away from each other. My problem is I cannot start 2 at the same time, whereas per design even 3 can start at the same time.

For the first 10 minutes, pump 1 starts and water was being pumped out, but then after 10 mins. we start the 2nd pump it trips off.

Can someone tell me what's the problem?
Can somebody tell me what to do? I am sure someone has encountered already this kind of situation.

 

Have you checked for excessive voltage drop on the supply lines?

 

A couple of questions come to mind.

1. How does the voltage react when P2 is brought online?
2. What is tripping out I.E. thermal overloads?

 

What is causing the trip? Overload? Circuit breaker trip? Pressure switch? Something else?

 

well i really havent ruled out the overload tripping, but after 10 mins. of running? There is got to be another problem rather than overload and it drives me crazy out here.. thanks...

We had replaced already the overload relay but still the problems comes again...i need to resolve this matter guys.... thanks...

 

Good Morning,
After reading the replies there are several critical pieces of info that have been asked for

1. voltage at start of P2
2. current and relationship to name plate values
3. What is tripping I.E. fuses , overloads etc...
4. inrush current
5. current on P1 at start of P2

There are several factors that can be causing this is it always at ten minutes? what happens if P1 runs longer? I would willing to assist you in greater detail

 

Responding to anonymous's 28-Jul (09:43) query...

The 10-minute delay certainly points to the OL! What are you required to reset before you can restart?

Regards,

 

You haven't given us much information, such as what is the actual voltage and current at the pump (or at a point close to it). If it is tripping on overload (as opposed to short circuit), then 10 minutes sounds like a reasonable time period. If there is too much voltage drop in the lines, then the load current will be higher and you can expect an overload trip.

 

Further to my 28-Jul (14:06) response to Anonymous:

Paraphrasing Alice of Wonderland fame, “This project gets curiouser and curiouser!” I would like to make the acquaintance of the salesperson that convinced your facility’s leader(s) to install a 750-Hp, 400-V motor with Y-D starting!

On a more serious note, are the listed parameters correct? And, is the motor 1-km from the starter? If so, then what is the capacity of the source of supply?

Regards, Phil Corso ([email protected])

 

in the panel itself of the pump no voltage drop, we are reading 400 v, i just let you know that the supply of the pump came from a step down xformer, 13.8 / 400 through transmission, wherein it came from step up x'former 400 / 13.8 supplied by a generator. But we are currently reading 13.5 kv with 1 pump running. after we start 2nd pump it reads 13kv then trips after 10 mins. So i cant really make
sure if it is on the pump side we had problem of with. We had already pulled out one of the submersible pump and we had found out that the rotor of it had been starting to break. And now we are running only one pump. and as of this two days it is going great with one pump running.

 

Responding to Anonymous' 29-Jul (23:26) observation:

Rotor bar damage, especially an increase in their length, is symptomatic of excessive starting time! Are there any indications of problems with the Y-D starter?

Phil ([email protected])

 

Ok! so far here are the facts as I see them for all that has been said here.

1. P1 runs as expected alone
2. P1 operating parameters are within manuf. specs
3. Voltage loss is minimal
4. P2 has a stator breaking down
5. P3 status unknown

Now for more questions, P2 is down with a bad stator. What happens when P3 is started?

Can you start and run P3 in place of P1?

The question as been asked several time what is tripping out?

Is the "trip out" always at ten minuites or is it event driven?

I have over thirty years of experiance in this field which tells me either we a friction load or an electrical break down.

The friction load is rather easy to identify a current meter or a current logging device should show any descrepancies.

The same hold true for the electrical side of the equation. Voltage meters, current meters should revel the electrical loads and or faults.

If the lag pump is causing the system to fault repeatably as a result of an event, isolate that event. If the "trip out" occurs at random times try using a recording device to revel the parameters at the time of fault.

Additionally when checking the system use analog equipment typicaly they will display events better than the digital instruments.

Clifford Fasnacht ([email protected])

 

You said "we had already pulled out one of the submersible pump and we had found out that the rotor of it had been starting to break". I don't suppose this might happen to be the pump which was tripping, was it?

If you are still having problems, I suggest that you get someone in who can look over the drawings, make some careful measurements, and come to some definite conclusions. At the very least you need to put an amp clamp on each of the pump conductors to see what is going on. I don't think I can help you any further over long distance.

 

We had started our P3 and this time tripping again at our mv switchgear at exactly 2 minutes and 30 seconds. We even shorten the time of the wye delta starter. And as we shorten the timer, the shorter it failed.

For the pump capacity, I think we had just purchased exactly what we want. We have 3 different wells for our submersible pump 1 km. away each other and about 2 km away from our power house. But the starter of the pump is just about 2 meters away. So if we had make a mistake purchasing this kind of pump please tell us...

Now we are waiting for the replacement of P1 and I will notify you what will happen and do personally the necessary test before and after we replace the P1 in the well.

 

Anonymous, your 01-Aug (10:17) post asked if a mistake was made regarding the pump. I believe, based on information provided to-date, that the electrical supply should be reviewed. I am willing to help! Can you arrange to send a Single-Line-Diagram (SLD), or simple sketch, showing the major component parameters!

Regards, Phil Corso ([email protected])

 

A pump takes more HP if it is pumping at a low head.
Try starting against a closed valve, then start opening the valve until full open or until the motor reaches the max amps for full load.

 

Does a timer switch this motor from Wye to Delta? if so what is the timer set for??