Hello,
We have a Goulds 5 CHC, 6 stg pump. Run by a 15 Hp, 230 v 60 Hz motor with 47.4 max Amps, 3450 RPM. It is driven by a 50 Hp Altivar 630. The problem we are having is every time we try and up the flow rate (pumping water), the VFD trips on overcurrent. We are currently stuck @ 7 L/s when we know the pump is capable of much more. We have changed out the motor and pump as well as new cable down to our deep well. And it still does the same thing!! What could be the reason for this? There are no breaks in our lines. The nameplate of motor is set into VFD with most of the correct info but the RPM does not match the nameplate, it is set to 1778. Is this the reason we can not achieve the desired flow rate? This is all new to us and we can not get anywhere with the suppliers. Any help or suggestions would be greatly appreciated thank you!!

 

That's generally your first point of call. Ensure your nameplate info is correct. Your RPM needs to be changed and it's a good idea to auto-tune if you already haven't done so.

 

VBV...
Welcome to Control.com:
1) Have you determined downhole cable impedance?
2) Do you know if overcurrent value is equal on all 3 phases?
3) Is downhole cable very long?
4) Is downhole cable 3-conductor or 4-conductor?
5) What are electrical parameters when motor is disconnected from Altivar?
6) What is Source Voltage and Frequency?
7) Do you have an Electrical Tech onsite?
Regards, Phil Corso

 

That's generally your first point of call. Ensure your nameplate info is correct. Your RPM needs to be changed and it's a good idea to auto-tune if you already haven't done so.

Hello, I did that and it caused nothing but major pressure issues back at the WTP, and would shut down on alarms. Tried the auto-tune as well but not sure it did anything.

 

Your desired flow depends on the head differential, and the pump curves. Get your process designer involved.

 

Your desired flow depends on the head differential, and the pump curves. Get your process designer involved.

Hi, thank you. I have tried to get them involved but they keep saying it is our pump. Which was brand new, we were achieving our desired flow but have had to change out motor and pump within a year. This is not normal. Pump and motor ran fine before all the automation/VFD were attached?

 

VBV...
Welcome to Control.com:
1) Have you determined downhole cable impedance?
2) Do you know if overcurrent value is equal on all 3 phases?
3) Is downhole cable very long?
4) Is downhole cable 3-conductor or 4-conductor?
5) What are electrical parameters when motor is disconnected from Altivar?
6) What is Source Voltage and Frequency?
7) Do you have an Electrical Tech onsite?
Regards, Phil Corso

Hi Phil, I can only answer to the best of my ability here as I do not have electrical background
1) Not to sure what downhole impedance is exactly.
2) I have no way of knowing if overcurrent value is equal on all three phases. I can only go by what the VFD alarms show me. Alarms are mostly Motor overload and ground short circuit. It is only when we increase flow rate that the overcurrent shuts VFD down. I do not have access to even the parameters for VFD settings.
3) Downhole cable is about 150'
4) The downhole cable 4c #2 well pump cable
5) I do not know what the electrical parameters are when not hooked to Altivar. We had an old Rotodyne before all of this, the plant is only 2 years old.
6) Source Voltage I can only assume is 240 V, 60Hz. We have had power company in to test incoming and they said tested fine.
7) We do not have an electrical tech onsite. We are a small village, with only 2 operators.

 

You'll have to pull the pump up and test it under discharge pressure control.

 

Hi VBV,

It is a while since I last configured an Altivar - I do recall they have a pretty useful front display.
When the VFD is running - what is the output frequency? Is it 30Hz or 60Hz? Is the current consistently above 50 Amps?

Internet curve for 5CHC006 model 05CHC01564CTB says 7L/s or 25m3/h is pretty healthy - see link below.
https://www.wcc.nrcs.usda.gov/ftpref/wntsc/Pump Curves/Goulds/3600/5CHC.pdf

Note - This pump and motor combination is not designed to lift from a 150 foot depth - extrapolating from the curve I see dead head (blocked outlet - maximum pressure) is about 140 foot equivalent on clean water.
At 150' your pump and motor is exceeding expectations.

My suggestion;
1. You have the wrong pump - you need a pump that will lift 150' plus whatever head (pressure) you need at the WTP - likely 200 kPag (30psi) -
2. The right pump will have a bigger motor - and probably 7 or 8 stages - you can then restrict the flow by adjusting the VSD maximum speed (i.e.; instead of 60Hz, try 57Hz).

For now - with your pump - the 5CHC006;
1. Download the Alivar 600 setup manual - search "altivar 600 quick start"
https://iportal2.schneider-electric.com/Contents/docs/SQD-ATV630U40S6X_USER GUIDE.PDF
2. Check all the settings on page 4 of the quick start - including very important "Motor Standard" - must be set to 60Hz as per nameplate.
If this wasn't set to 60Hz - do a test run - your problems may be fixed ...
Otherwise
3. Set VSD parameter motor thermal current to 10% above actual nameplate - i.e.; [Motor Th Current]ITH = 48A *1.1 = 53A
4. Set VSD parameter current limitation to actual nameplate [Current Limitation] CL=48A
Do a test run - the VSD should ramp the motor to nameplate current 48A - it will limit at this point forever no problem.

The earth fault is concerning - this usually indicates damaged windings or a bad cable join.
It doesn't normally go away ... so possibly something else is happening.

Good luck, keep your village happy!

 

It is usually the first port of call. Make sure the file name is correct. If you need to change the RPM and you haven't, we recommend performing an autotune.

 

Hi Again,

Thinking this through - your pump probably has 30-40' of static head - i.e.; pump set depth at 150', at maximum aquifer draw down there is still 30' of water above the pump.
This means you will have 20' head up your sleeve, which must be enough to feed the WTP.

Assuming the pump curve and motor match the internet curve - we still have the problem why is the current too high for 7L/s flow? Possibly your pump hose has a split and flow is recycling inside the bore - this will push the pump to the right of the curve and cause the motor to work harder.
Check the hose at the next opportunity.

I would still set the current limitation to 48A (you will need to find this setting in the Altivar setup).

 

I've tried including them, but they keep saying it's our pump. Got the flow I wanted with a new one, but within a year the motor and pump need to be replaced. there was This is not normal, the pump and motor were running properly before all the automation/VFD was activated?