Rating of VSD required to drive a submersible pump 220 kW 4

[SA07]

Hi
Can you please confirm if a VSD 220 kW is enough to drive a submersible pump 220 kW? Medium is raw water from a borehole. Or should we use a slightly higher rating than 220 kW e.g 250 kW?

VSD Schneider ATV630C25N4 220 kW 380-440 V IP00

Submersible pump:

kW 220 kW
Rated Current 390A
Speed/rpm 2945 rpm
Frequency 50 Hz
Rated Voltage 400V

 

[itsmoked]

It's not hard but you have to do it.

Line up all the specs between the VFD and the motor.


Motor FLA verses drive 100% output current.

Motor Voltage verses drive voltage.

Motor Poles: make sure that's an available choice in the drive parameters.

You can't go by just the kW ratings because some motors will draw LARGE currents while still only being low kW rated.


Also check the distance from the drive to the motor. If it exceeds X meters you will need to use an output filter or choke. The drive manual will usually state what the distance is.



Keith Cress
kcress -

http://www.flaminsystems.com

 

[LittleInch]

More importantly, why do you want a VFD for such a duty? Where the static head is such a large part of the discharge head VFDs are often a bad choice and find it hard to vary the flow rate.

That's a big pump for a bore hole.

You need to match pump to motor to drive.

Also don't forget the vfd losses so inlet power is higher still.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[jraef]

Rule #1 on sizing VFDs: Always size VFDs based on motor nameplate Full Load Amps. Never use HP or kW, because that's not what the VFDs are rated for, that's a "convenience". VFDs are rating in AMPS. That's what counts.

Rule #2: when in doubt, refer to Rule #1.

Rule #3: (for those in North America) when implementing Rule #1, do not use the motor Service Factor Amps (SFA), because the MOTOR manufacturers will tell you that when the motor is run from a VFD, the SF becomes 1.0, so there is no point in over sizing the VFD to cover a Service Factor you cannot use. (I know this may be confusing to the IEC world, but trust me, it's an issue I deal with a lot).

Corollary to Rule #1: VFD sizing has an aspect based on whether a load machine is "Constant Torque" or "Variable Torque". Variable torque loads are machines like centrifugal pumps and fans (quadratic for the IEC crowd) because as such, the nature of the load means it cannot be overloaded, so there is no need for the transistors in the VFD to be rated for overload conditions. In a centrifugal load, the only way to overload them is to INCREASE the flow, and if the machine was sized correctly, that should be impossible. So VFDs rated for "Variable Torque" or some call it "Normal Duty" or "Pump and Fan Duty" are sized to not have to provide very much overload capacity, usually 110% for 30 to 60 seconds. "Constant Torque" loads are basically everything that is NOT a centrifugal machine, and CT rated drives (also called "Heavy Duty") use larger transistors to be able to handle overload conditions, usually involving step-changes in load and the need to re-accelerate after that happens. They can typically handle 150% of rated current for 60 seconds.

SA07,
Your submersible pump could be either a centrifugal (turbine) pump or it could be a Positive Displacement (rod) pump, we don't know. That is something you will have to determine. If it is water, it is likely a turbine pump and therefore centrifugal. If it is oil, it's likely a rod pump and Positive Displacement. The PD pump would require a CT/ Heavy Duty rated drive. The drive you posted is rated for 481A output as a Normal Duty (VT) drive, so would be fine for a 390A motor. But it is only rate for 387A as a Heavy Duty (CT) drive, so would fall short of your required 390A if it is a PD pump.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[SA07]

The submersible pump is used to pump raw water from a borehole for sugar cane field irrigation. It can also be used to supply a power plant with water. The demand may varies. That is why we are using a VSD to vary the flow.


Motor nameplate:

kW 220 kW
Rated Current 390A
Speed/rpm 2945 rpm
Frequency 50 Hz
Rated Voltage 400V


VSD nameplate:

Schneider ATV630C22N4
Supply 380-480 V
Motor power 160 kW (Heavy Duty) 220 kW (Normal Duty)
Continuous Output Current 302 A at 2.5 kHZ Heavy Duty, 427 A at 2.5 kHz Normal Duty

Supply in the country is 3 phase 400 Vac

 

[SA07]

Plz see attached VSD, submersible data sheet.

 

[LittleInch]

Just use a control valve. Seriously.

VFD control for systems where a large part of the system curve is static head are inefficient and don't work well.

Why? Head varies by the square of the speed.

If you need say a min of 150m head to get any water out of the well but then only 30 more m to make it flow then your frequency range is very small. Your VFDs is quite efficient by the look of it and emits only 5.5 kW as waste heat.

Power consumed by a pump reduces as flow reduces when controlled by a valve. To be fair that pump has a steep efficiency curve so less flow only reduces shaggy power by about 20kW.

But unless you have pump curve for different speeds you won't know if this changes.

Just plug the pump into your switch gear and forget about the vfd or at least get a pump system engineer to look at the two options.

Think very carefully about how long it operates at different flow rates.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Compositepro]

Little Inch is correct that this is a very poor application for a VFD. The pump must run at close to full speed just to generate the head to get the water to the wellhead. In this case, a VFD will not only cost more than a valve, it could use more total power than a throttle valve.

 

[Valvecrazy]

I have been scolded many times for saying a control valve can be as or more efficient than a VFD for centrifugal pumps in high head applications, but it is very true. As long as the water is fairly clean a control valve can be a much less expensive and less troublesome option. However, control valves have a limit in pressure as well. Make sure to stay within the valves pressure limits.