Variable Frequency Drives - Pumps & Systems · Selection for VFD Systems Pumps & VFDs Webinar September 2014 Second rule of thumb: For variable speed applications, select pumps with

Presented by: Chris Caldwell, Sulzer-ABS Sean Fitzpatrick, Schneider Electric/Square D

Variable Frequency Drives

Industry Webinar 9-14

Pumping Systems & Controls Training Seminar

2011

• Participants are in a listen-only mode.

• To ask a question during the event, use the chat feature at the bottom left of your screen. Technical questions will be answered by ReadyTalk. Questions for our speakers can be asked at any time and will be answered during the Q&A at the end of the session.

• Visit pump-zone.com in the coming days to access the recording of the webinar or download the presentation.

© Copyright 2014. Submersible Wastewater Pump Association (SWPA)

Presented by: Chris Caldwell, Sulzer-ABS Sean Fitzpatrick, Schneider Electric/Square D

Variable Frequency Drives

Industry Webinar 9-14

Pumps & VFDs Energy Savings and MORE!

Protection, Prevention, Communication


2011

© 2014 Submersible Wastewater Pump Association

Energy Savings with VFD Pump Systems

Pumps & VFDs Webinar

September 2014

Typical pump life-cycle cost profile (Courtesy of Hydraulic Institute and Pump Systems Matter)

Energy represents 40% or more of Total Life Costs of many pump systems The majority of pump applications offer Energy savings potential Most all states have utility driven incentive programs to install/upgrade VFDs in pump applications


2011



September 2014

Typical pump life-cycle cost profile (Courtesy of Hydraulic Institute and Pump Systems Matter)

What if these same VFDs could reduce operating costs in areas such as

Pump maintenance Pump operations Downtime

Represents an additional 38% of pump life-cycle costs

Other Savings with VFD Pump Systems


2011

Energy Efficiency

Water Crisis/Efficiency

Urbanization

Intelligent Pumping

Environmental

Impact/Operating Costs

Intelligent Pumping Pumps & VFDs Webinar

September 2014


2011


Application and Pump Selection for VFD Systems


September 2014

While many pumping applications will benefit from VFDs, not all applications are appropriate.

To maximize energy savings it’s important to understand where VFDs are of benefit, and where other starting methods are more appropriate. In a properly selected VFD application, where does the energy savings come from?


2011




September 2014

The Affinity Laws predict the performance of a centrifugal pump at differing speeds.

• The change in flow is proportional to the change in speed.

• The change in head is proportional to the square of the change in speed.

• The change in power is proportional to the cube of the change in speed.

32

31

2

1

22

21

2

1

2

1

2

1

nn

PP

nn

HH

nn

QQ

=

=

=

Q = flow H = head pressure P = power


2011




September 2014

Reducing the frequency (and rotational speed) from 60Hz to 50 Hz, or about 16.7% results in:

A flow reduction of 16.7% to 1667 gpm

A head reduction of 30.6% to 69.4 feet

A power reduction of 42.1% to 38.8 hp

Of course the pump will not necessarily run at this new flow and head. The actual new operating point depends on where the system head curve intersects with the reduced speed pump curve.


2011




September 2014

Slowing the pump down with a VFD helps reduce the power consumed overcoming the dynamic losses in the system (friction in the pipes and fittings).

Slowing the pump down does not help with overcoming the static head in a system.

Static head is the enemy, and pretty much all pump applications have it. Systems with a low percentage of static head in the total head make good VFD applications and systems with a high percentage of static head do not make good VFD applications.

Let’s look at some curves to see why.


2011




September 2014

350

70%

PE1040/4

Head

Q / US g.p.m.0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800

H / ft

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

Typical six inch, 140 hp submersible pump curve


2011




September 2014

350

70%

PE1040/4

Head

Q / US g.p.m.0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800

H / ft

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

55 Hz

70%

PE1040/4

50 Hz

70%

PE1040/4

45 Hz

70%

PE1040/4

40 Hz

70%

PE1040/4

35 Hz

70%

PE1040/4

Add reduced speed curves at 5 Hz intervals, down to 35 Hz


2011




September 2014

350

70%

PE1040/4

Head

Q / US g.p.m.0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800

H / ft

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

55 Hz

70%

PE1040/4

50 Hz

70%

PE1040/4

45 Hz

70%

PE1040/4

40 Hz

70%

PE1040/4

35 Hz

70%

PE1040/4

60 %

65 %

65 %

68 %

68 %

69 %

69 %

Add lines of constant efficiency


2011




September 2014

350

70%

PE1040/4

Head

Q / US g.p.m.0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800

H / ft

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

55 Hz

70%

PE1040/4

50 Hz

70%

PE1040/4

45 Hz

70%

PE1040/4

40 Hz

70%

PE1040/4

35 Hz

70%

PE1040/4

60 %

65 %

65 %

68 %

68 %

69 %

69 %

A1

Add duty point A1, 1,800 gpm at 160 feet of head

Add system head curve with a static head of 60 feet


2011




September 2014

350

70%

PE1040/4

Head

Q / US g.p.m.0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800

H / ft

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

55 Hz

70%

PE1040/4

50 Hz

70%

PE1040/4

45 Hz

70%

PE1040/4

40 Hz

70%

PE1040/4

35 Hz

70%

PE1040/4

60 %

65 %

65 %

68 %

68 %

69 %

69 %

A1

Same duty point except the static head is now 145 feet

Very flat system curve forces the reduced speed operating point to move left very quickly


2011




September 2014

First rule of thumb: Applications where the static head is greater than 50% of the

total head are not usually good applications for VFD variable speed pumping. This is because:

Since the system curve is very flat, the pump efficiency at the reduced speed operating point falls off rapidly. The opportunity for energy savings at reduced speed is minimal.

Since the system curve is very flat, there is very little useable speed reduction range.

Pump rotational speed at reduced speed, lower flow conditions remains very high, resulting in high energy recirculation cavitation, which can damage the pump.


2011




September 2014

363.8*

68.3%

PE1040/4

Head

Q / US g.p.m.0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100

H / ft

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

250

260

55 Hz

68.3%

PE1040/4

50 Hz

68.3%

PE1040/4

45 Hz

68.3%

PE1040/4

40 Hz

68.3%

PE1040/4

35 Hz

68.3%

PE1040/4

30 Hz

68.3%

PE1040/4

60 %

60 %

64 %

64 %

66 %

66 %

68 %

68 %

Alternate pump selection with best efficiency point further to the left

Previous pump had the full speed BEP at about 1,950 gpm. With this pump, it’s about 1,480 gpm


2011




September 2014

363.8*

68.3%

PE1040/4

Head

Q / US g.p.m.0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100

H / ft

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

250

260

55 Hz

68.3%

PE1040/4

50 Hz

68.3%

PE1040/4

45 Hz

68.3%

PE1040/4

40 Hz

68.3%

PE1040/4

35 Hz

68.3%

PE1040/4

60 %

60 %

64 %

64 %

66 %

66 %

68 %

68 %

A1

The same 1800 at 160 duty point, and 60 feet of static head


2011




September 2014

363.8*

68.3%

PE1040/4

Head

Q / US g.p.m.0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100

H / ft

10

20

30

40

50

60

70

80

90

100

110

120

130

140

150

160

170

180

190

200

210

220

230

240

250

260

55 Hz

68.3%

PE1040/4

50 Hz

68.3%

PE1040/4

45 Hz

68.3%

PE1040/4

40 Hz

68.3%

PE1040/4

35 Hz

68.3%

PE1040/4

30 Hz

68.3%

PE1040/4

60 %

60 %

64 %

64 %

66 %

66 %

68 %

68 %

A1

The same 1,800 at 160 duty point, and 145 feet of static head


2011




September 2014

Second rule of thumb: For variable speed applications, select pumps with the full

speed operating point to the right of BEP whenever possible, especially with systems having a high percentage of static head.

Selecting to the right of BEP improves efficiency at reduced speed since the intersection point with the system curve moves toward BEP when slowing down.

Variable speed applications often allow the use of smaller, less expensive pumps.

Smaller pumps and selections right of BEP provide the best opportunity for energy savings at reduced speed (where the pumps run most of the time).

Check NPSH margin for all selections, especially when selecting to the right of BEP!


2011


Assuming a proper application, what else will a VFD do for you Pumps & VFDs

Webinar September 2014

Soft starting/stopping capability Reduction of mechanical stress, extending the life of both pump & motor, reducing maintenance expenses Reduction and/or elimination of water hammer caused by an abrupt change of flow Elimination of starting inrush currents (6-8X motor FLA) – reduce likelihood of peak demand charge penalties Some utilities require that motors over a certain horsepower undergo a soft start Inherent Power Factor correction, increasing efficiency


2011


VFD functions Pumps & VFDs Webinar

September 2014

Typical VFD built in functionality includes:

Motor thermal overload protection Phase loss/reversal detection Built-in equipment efficiency monitoring to optimize systems Sleep/wake function - to stop the motor in standstill situations. Results in energy savings and prevents premature aging of equipment


2011



September 2014

Pump specific VFD functionality may include:

Loss of prime detection Low/no flow detection – prevent the pump from being damaged or destroyed under these conditions Low/high pressure level detection – sensor-based solution to prevent pump damage Broken pipe detection Pump over cycle protection Advanced sleep/wake function

POWER TREND

Alarm


2011



September 2014

Pump Specific VFD functionality may include:

Pump cycle start protection – provides an alarm signal to prevent excessive starting Cavitation protection Impeller wear indication and alarming Drift detection with user-defined allowable limits Dry run protection – sensor-less and sensor-based solutions to prevent pump damage


2011



September 2014

Pump Specific VFD functionality may include:

Sensorless flow – estimates flow based on input of specific pump curves Jockey pump control – increases system efficiency in low demand situations Anti-jam protection – allows for manual or automatic forward and reverse pump rotation Pipe fill function – reduce or eliminate waterhammer Friction loss compensation – offset pressure drop over the pipeline system


2011 Maintenance Reduction Corrective Maintenance:

“The pump seal has failed – we need to fix it now!”

Preventive Maintenance:

“The pump seals fail after 2.5 years on average, so we’ll replace them during shutdown every two years.”

Predictive Maintenance: “We can see the pump performance is drifting – looks

like the seal is starting to go, we need to replace it at the next opportunity.”



September 2014


2011



September 2014 Diagnostic Logs

Time stamping of events Current and historical error conditions Current and historical warning conditions Configurable ‘customer warnings’



2011



September 2014 Dynamic QR codes The display can create a QR code which can be used to:

Access online

documentation

Automatically create a support ticket

Report diagnostic information

Dynamic QR codes for diagnostics information and online manuals and information











September 2014


2011



September 2014 Pump Operations Data A VFD may track and record pump operation history:

Run time

Number of starts

Custom warnings –

set a date and time for an alarm to occur











September 2014


2011



September 2014 Pump Curves

Pump curves can be entered into the drive to monitor pump performance: Application efficiency Predictive maintenance



2011



September 2014 Pump Curves

Analysis of pump performance can provide information on application problems and maintenance problems



2011



September 2014

Embedded web server – access information any time, anywhere


2011



September 2014

Integrated PID Control – Eliminating the need for an external PID controller

Costs less Simpler to configure Reduces of the integration need of multiple-control components Reduce wiring costs and possibility of loose connections Requires less panel space Reduces maintenance


2011



September 2014

Phase Conversion – The VFD converts incoming AC power to DC whether the source is single or three phase. Regardless of the input power, the output will always be three phase.

As a rule of thumb, for a drive supplied by single phase input most manufacturers recommend using a drive that is double the motor size to handle the increase in current.

Must always select three-phase pump motor.

Low harmonic systems available for placement of relatively high loads onto these power grids.


2011

Don’t miss SWPA’s two-day Pumping Systems and Controls Training Seminar –

all based on the systems approach.

November 5-6 – Chicago, Ill.

Register by calling 847.681.1868 or visiting swpa.org.

Today’s webinar attendees may receive

½ off their registration.*

*offer available to first-time SWPA Training Seminar attendees only


2011 Q & A

To contact today’s presenters, email: Chris Caldwell – [email protected]

Sean Fitzpatrick- [email protected]

Visit pump-zone.com in the coming days to access the recording of the webinar or download the presentation.

The next webinar in the SWPA series will be on December 11, 2014. More details coming soon.

Documents

Variable Frequency Drives - Pumps & Systems · Selection for VFD Systems Pumps & VFDs Webinar September 2014 Second rule of thumb: For variable speed applications, select pumps with