ASRAC Pumps Working Group Metric: Calculations and

BUILDING TECHNOLOGIES PROGRAM March 26-27, 2014

ASRAC Pumps Working Group

Metric: Calculations and Standard Setting

2

Review of PER metric and issues from last meeting

Detailed examples for test procedure approach

• Calculation-based method

- How to account for motor efficiency at part load and controls

• Testing-based method

Load point options

• Vote?

Weighting options

• Vote?

Denominator options

Overview

3

Metric Applicability to Pump Configurations

Pump Configuration

Bare Pump Bare Pump + Driver Bare Pump + Driver + Controls

Met

ric

Co

vera

ge

Bare Pump Does not include motor efficiency

Does not describe control losses or benefits

Bare Pump + Driver

(w/ std. driver)

Does not describe control losses or benefits

Bare Pump + Driver + Controls

(w/ std. driver and controls)

(w/ std. controls)

Pu

mp

Driver

Pu

mp

Driver Control

Pu

mp

4

Covered Product Metric

Bare Pump Efficiency or Energy

Use

Driver Efficiency or Energy

Use

Controls Efficiency or Energy

Use

‘Pump’ Efficiency or Energy Use =

5

Possible Metric

Pump Energy Rating (PER): equally weighted average electric input power (P1) to the ‘pump’ measured (or calculated) at the driver input or, when present, controls input, over a specified load profile (110%, 100%, 75%, and 50% of Best Efficiency Point (BEP) flow at nominal speed).

• For bare pump or pump+driver, achieve part-load by throttling through pump curve at rated speed.

• For pump+driver+controls, achieve part-load by reducing speed and correcting to a specified system curve shape.

PER = 0.25(P1BEP) + 0.25(P11.1BEP) + 0.25(P10.75 BEP) + 0.25(P10.5 BEP)

Notes:

Denominator could be included in metric

Rating points, load points, and weighting must be determined

6

Issues to Discuss • Metric

– Denominator

• Motor losses – bring examples to 3/26 meeting

– Full load only, different loss curves for different types of motors?

• Method to account for controls – bring examples to 3/26 meeting – Testing for drive efficiency? – Load Control Factor to account for different types: VSD, multi-speed motors,

ECMs?

• Load points (i) - % of BEP flow – 50%, 75%, 100%? – 25%, 50%, 75%, 100%? – 75%, 100%, 110%? – 50%, 75%, 100%, 110%?

• Weighting (wi)

– Equal weighting? (w=0.25)

𝑷𝑬𝑹 = 𝑳𝑪𝑭

𝝎𝟎.𝟓𝟎𝑷𝟎.𝟓𝟎

η𝒎𝒐𝒕𝒐𝒓,𝒅𝒆𝒇𝒂𝒖𝒍𝒕+ 𝝎𝟎.𝟕𝟓

𝑷𝟎.𝟕𝟓η𝒎𝒐𝒕𝒐𝒓,𝒅𝒆𝒇𝒂𝒖𝒍𝒕

+ 𝝎𝑩𝑬𝑷𝑷𝑩𝑬𝑷

η𝒎𝒐𝒕𝒐𝒓,𝒅𝒆𝒇𝒂𝒖𝒍𝒕+ 𝝎𝟏.𝟏

𝑷𝟏.𝟏η𝒎𝒐𝒕𝒐𝒓,𝒅𝒆𝒇𝒂𝒖𝒍𝒕

𝑷𝑯𝒚𝒅𝒓𝒐

7

Metric Options

• PER

• MEI – describes pump only

• EEI – describes impact of controls only

• gpm / kWh for electric pump/driver combinations

• gpm / Btu for non-electric pump/driver combinations

• kWh / gpm for electric pump/driver combinations

• Btu / gpm for non-electric pump/driver combinations

• kWh / (gallons or gpm * feet of head) for electric pump/driver combinations

• Btu / (gallons or gpm * feet of head) for non-electric pump/driver combinations

8

Calculation methods

• Bare shaft pump

• Bare pump sold with motor

• Bare pump sold with motor and control (VFD)

Test methods

• Bare pump sold with motor

• Bare pump sold with motor and control

Sample Calculations of the PER Metric

9

Pump Used for Example Calculations

Note that this example is for a pump and motor combination. If the working group decides to include engine-driven pumps in the scope of this rulemaking, similar calculation methods will have to be developed or a separate physical test applied.

Pump Motor (if applicable) Controls

Type: OH1 Rated conditions: • Rated Flow: 900 GPM • Rated Head: 160 ft • Rated Speed: 1750 RPM

Power: 60 hp Efficiency: 95% No load speed (Test Motor): 1780 RPM [four pole motor]

Various

10

PER Calculation: Determining BEP Flow Rate (Q100%)

• 7 points swept from shutoff to maximum flow rate, with flow rate (GPM), Head (ft), rotational speed (rpm), torque (in-lbf) recorded in following table

• Hydraulic pump efficiency is calculated at each flow point

– Input power = (torque) x (speed)

– Output power = (flow rate) x (head) x (specific weight of fluid)

– Efficiency = output power / input power

• BEP found by determining maximum of best fit curve of efficiency with respect to flow rate

% of BEP flow

Flow Rate (GPM) Head (ft)

Speed (RPM)

Torque (lb-in)

Hydraulic Power

(hp) Shaft input power (hp) η (%)

η [best fit] (%)

128 1200.59 141.51 1774.10 1977.14 41.76 55.65 75.04 74.42 108 1012.80 157.91 1774.63 1782.87 39.31 50.20 78.31 77.57

100 939.62 162.58 1774.80 1721.36 37.55 48.47 77.47 77.86 91 851.24 169.44 1775.86 1613.80 35.46 45.47 77.97 77.65

76 709.87 178.40 1775.85 1458.85 31.13 41.11 75.73 75.96 58 547.19 186.61 1777.84 1251.15 25.10 35.29 71.12 71.22

48 449.06 189.67 1778.80 1112.42 20.94 31.40 66.69 66.18

11

× standardized motor

efficiency (and part load curve?)

MOTOR

pump performance data from pump test at rated

speed

Bare Pump

× standardized controls

performance

Controls

• Standard motor: AC Induction, NEMA Design B, open enclosure. • HP used will be next HP above brake horsepower at 120% of BEP HP. • Poles will be based on speed at which pump is being rated.

Issues • Standardized Motor Performance

• Standard full load motor efficiency for all points, based on Federal standards; or • Develop standard motor part-load curves.

• Standardized Controls Performance • Assume 100% efficiency; or • Develop standard control efficiency, potential with part-load curves.

12

Determining Bare Pump Performance

• Determine brake hp at Q50%, Q75%, Q100% and Q110% flow rates

– Pump brake hp obtained from best fit curve of brake hp vs flow rate

Load Point Flow rate [GPM] Pump brake hp [HP]

Q110% 1034 50.65

Q100% 940 47.66

Q75% 705 40.16

Q50% 470 32.66

𝑷𝑬𝑹 = 𝑳𝑪𝑭 𝝎𝟎.𝟓𝟎

𝑷𝟎.𝟓𝟎


𝑷𝟎.𝟕𝟓

η𝒎𝒐𝒕𝒐𝒓,𝒅𝒆𝒇𝒂𝒖𝒍𝒕+ 𝝎𝑩𝑬𝑷

𝑷𝑩𝑬𝑷


𝑷𝟏.𝟏

η𝒎𝒐𝒕𝒐𝒓,𝒅𝒆𝒇𝒂𝒖𝒍𝒕

𝑷𝑬𝑹 = 𝑳𝑪𝑭 𝟎. 𝟐𝟓𝟓𝟎. 𝟔𝟓 𝒉𝒑

η𝒎𝒐𝒕𝒐𝒓,𝒅𝒆𝒇𝒂𝒖𝒍𝒕+ 𝟎. 𝟐𝟓

𝟒𝟕. 𝟔𝟔 𝒉𝒑


𝟒𝟎. 𝟏𝟔 𝒉𝒑


𝟑𝟐. 𝟔𝟔 𝒉𝒑


13

Accounting for Motor Losses

• Full load motor efficiency (ηmotor,default) for the bare shaft pump PER calculation obtained from Table 3 in 10 CFR 431.25 (subpart B) – Determine pump shaft hp at 120% of BEP flow = 1128 GPM = 53.65 hp -> 60 hp

– For a four pole motor with rated load of 60 hp, the full load efficiency ηrated

DOE = 93.6%

• To account for motor losses with decreased loading, one could calculate motor losses at each load point based on a load fraction: – Calculate load fraction (brake hp at each load point

divided by rated motor load [60 hp])

• From load fraction and part load points obtained from brake hp data, estimate the part-load loss factors at each motor load point using an equation: – yi = 0.12xi

3 + 0.18xi2 + 0.4xi +0.3

• Where yi is the loss factor at each load point (i), and xi is the load fraction for each load point

𝒙𝒊 =𝑷𝒊

𝑴𝒐𝒕𝒐𝒓𝑺𝒊𝒛𝒆[𝒉𝒑]=

𝑷𝒊

𝟔𝟎 𝒉𝒑=

𝟓𝟎. 𝟔𝟓

𝟔𝟎= 𝟎. 𝟖𝟒𝟒

14

Accounting for Motor Losses

• Calculate the fractional load loss at each flow point using: 𝐿𝑖 = 𝐿𝑓𝑢𝑙𝑙,𝑟𝑎𝑡𝑒𝑑 ∗ 𝑦𝑖

– Where Li is the fractional load loss at each flow point in hp, Lfull,rated is the full load losses determined in accordance with 10 CFR 431.25 (subpart B) in hp, and yi is the part load loss factor for each flow point

• Calculate the fractional input power as follows: 𝑃𝑖𝑛𝑖 = 𝑃𝑖 + 𝐿𝑖

– Where Pi is the bare shaft input power in hp and the fractional load loss at each flow point, Lfull,rated is the full load losses determined in accordance with 10 CFR 431.25 (subpart B)

– Calculate fractional input power as follows: Piin

= Pi + Li

% BEP flow

Bare pump shaft input power (hp)

Load fraction

(xi) Part load loss

factor (yi) Fractional load

loss (hp)

Fractional input power

(hp) 110 50.65 0.84 0.84 3.44 54.09

100 47.66 0.79 0.79 3.25 50.90

75 40.16 0.70 0.68 2.81 42.97 50 32.66 0.54 0.59 2.42 35.08

15

Determining Bare Pump Performance - Calculations

• Calculate PER by weighting each of the input power values as follows:

• Assume standardized load control factor of 1.

𝑷𝑬𝑹 = 𝑳𝑪𝑭 𝟎. 𝟐𝟓 𝟑𝟓. 𝟎𝟖 𝒉𝒑 + 𝟎. 𝟐𝟓 𝟒𝟐. 𝟗𝟕 𝒉𝒑 + 𝟎. 𝟐𝟓 𝟓𝟎. 𝟗𝟎 𝒉𝒑 + 𝟎. 𝟐𝟓 𝟓𝟒. 𝟎𝟗 𝒉𝒑

𝑷𝑬𝑹 = 𝟒𝟓. 𝟕𝟔 𝒉𝒑

16

Motor Losses Equation

• Motor loss curves based on Motor Masters Database

• Different load loss curves for ODP/TEFC and 2-pole/4-pole motors

• Other options?

y = 0.12x3 + 0.18x2 + 0.4x + 0.3

0

0.2

0.4

0.6

0.8

1

1.2

0 0.5 1 1.5Frac

tio

n o

f fu

ll lo

ad p

ow

er

loss

Fraction of full load power

ODP motors at 3600 RPM

Cubic Polynomial

Motor Masters Data

Poly. (CubicPolynomial)

17

× manufacturer motor

efficiency at full and part load

MOTOR

Bare Pump + Motor

Manufacturer can pair its pump data with manufacturer

motor data. pump performance data from pump

test at rated speed

standardized controls

performance

Controls ×

MOTOR PUMP

Manufacturer can measure power of

pump+motor combo.

standardized controls

performance

Controls ×

motor/drive performance data

B

A

18

Determining Bare Pump + Motor Performance – Calculation Method

• Calculate PER using the same method as for the bare shaft pump except:

– Incorporate the rated motor efficiency rather than DOE minimum efficiency

• Assume 60 hp motor with ηmotor,meas = 95% (Lfull,rated = 3.16 hp) and other values as before:


𝑷𝟎.𝟓𝟎

η𝒎𝒐𝒕𝒐𝒓,𝒎𝒆𝒂𝒔+ 𝝎𝟎.𝟕𝟓

𝑷𝟎.𝟕𝟓

η𝒎𝒐𝒕𝒐𝒓,𝒎𝒆𝒂𝒔+ 𝝎𝑩𝑬𝑷

𝑷𝑩𝑬𝑷

η𝒎𝒐𝒕𝒐𝒓,𝒎𝒆𝒂𝒔+ 𝝎𝟏.𝟏

𝑷𝟏.𝟏

η𝒎𝒐𝒕𝒐𝒓,𝒎𝒆𝒂𝒔

𝑷𝑬𝑹 = 𝟏 ∗ 𝟎. 𝟐𝟓 𝟑𝟒. 𝟓𝟑 𝒉𝒑 + 𝟎. 𝟐𝟓 𝟒𝟐. 𝟑𝟐 𝒉𝒑 + 𝟎. 𝟐𝟓 𝟓𝟎. 𝟏𝟓 𝒉𝒑 + 𝟎. 𝟐𝟓 𝟓𝟑. 𝟑𝟎 𝒉𝒑

𝑷𝑬𝑹 = 𝟒𝟓. 𝟎𝟖 𝒉𝒑

% BEP flow

Bare pump shaft input power (hp)

Load fraction

(xi) Part load loss

factor (yi) Fractional load

loss (hp)

Fractional input power

(hp) 110 50.65 0.84 0.84 2.65 53.30 100 47.66 0.79 0.79 2.50 50.15

75 40.16 0.70 0.68 2.16 42.32 50 32.66 0.54 0.59 1.86 34.53

19

pump performance from pump test at rated and reduced speed

× motor/drive performance

data

B

C

VFD MOTOR

Controls MOTOR PUMP

Bare Pump + Motor + Controls

Manufacturer can pair its pump data

with tested motor+VFD data.


pump+motor+ controls combo.

× manufacturer or default

motor efficiency

A MOTOR


motor data and default factor for

controls. pump performance

data from pump test at rated speed

default controls performance

Controls ×

20

• Instead of wire-to-water or full drive system testing, could apply a calculation factor to account for energy savings from control to PER of uncontrolled pump + motor:

• PER calculated for all three control options using : – bare pump shaft input power at BEP flow,

– motor nameplate efficiency, and

– pump affinity laws

Determining Bare Pump + Motor + Controls Performance –


𝑷𝟎.𝟓𝟎

η𝒎𝒐𝒕𝒐𝒓,𝒎𝒆𝒂𝒔+ 𝝎𝟎.𝟕𝟓

𝑷𝟎.𝟕𝟓

η𝒎𝒐𝒕𝒐𝒓,𝒎𝒆𝒂𝒔+ 𝝎𝑩𝑬𝑷

𝑷𝑩𝑬𝑷

η𝒎𝒐𝒕𝒐𝒓,𝒎𝒆𝒂𝒔+ 𝝎𝟏.𝟏

𝑷𝟏.𝟏

η𝒎𝒐𝒕𝒐𝒓,𝒎𝒆𝒂𝒔

21

Control factor: Basis

In this example, load control factor is defined as the ratio of PER of a speed controlled pump to the PER of an uncontrolled pump

• 𝐿𝐶𝐹 = 𝑃𝐸𝑅𝐶𝑜𝑛𝑡𝑟𝑜𝑙𝑙𝑒𝑑

𝑃𝐸𝑅𝑈𝑛𝑐𝑜𝑛𝑡𝑟𝑜𝑙𝑙𝑒𝑑

• Load control factor for the VFD provided in PER calculation example varies depending on load profile and weighting

PER of pump+motor will be used to determine the LCF for each control option

Need to assume specific control options:

• Potential control options could include multi-speed motors, brushless DC (or ECM) motors and VFD controllers

Use an assumed conservative system curve for all three options with following variations to determine the Load Control Factor

• Account for motor losses in conservative LCF

Assumptions:

• Efficiency of control = 96%

22

Control factor: VFD

• Calculate PER using flow points along system curve, rather than using flow points along one constant speed pump curve (but no over-speeding)

• The system curve is defined by the following pump affinity laws:

• 2.8 power exponent based on ASHRAE data suggesting real-life system curves have a relationship between head and flow with an exponent from 1.8 to 1.9

𝑸𝟏

𝑸𝟐=

𝒏𝟏

𝒏𝟐

𝑯𝟏

𝑯𝟐=

𝒏𝟏

𝒏𝟐

𝟏.𝟖

𝑷𝟏

𝑷𝟐=

𝒏𝟏

𝒏𝟐

𝟐.𝟖

Reference System Curve H

Q

Q100% Q75% Q50%

H100%

Q110%

23

Control factor: VFD - Calculations

• The flow at input power to the bare pump are available from the tested pump performance:

• Using the pump affinity laws, the bare pump shaft input power at 75% of BEP flow (660 GPM) is:

• Applied to all rating points yields the following:

𝑷𝑩𝑬𝑷 = 𝟒𝟕. 𝟕 𝐡𝐩; 𝑸𝑩𝑬𝑷 = 𝟗𝟒𝟎 𝑮𝑷𝑴

𝑷𝟏

𝑷𝟐=

𝒏𝟏

𝒏𝟐

𝟑

=𝑸𝟏

𝑸𝟐

𝟐.𝟖

𝑷𝟎.𝟕𝟓

𝟒𝟕. 𝟔𝟔 𝒉𝒑=

𝟕𝟎𝟓 𝑮𝑷𝑴

𝟗𝟒𝟎 𝑮𝑷𝑴

𝟐.𝟖

𝑷𝟎.𝟕𝟓 = 𝟒𝟕. 𝟔𝟔 𝒉𝒑𝟕𝟎𝟓 𝑮𝑷𝑴

𝟗𝟒𝟎 𝑮𝑷𝑴

𝟐.𝟖

= 𝟐𝟏. 𝟑𝟎 𝒉𝒑

Load Point Flow (GPM) Bare pump input power (hp)

Q110% 1034 53.56

QBEP 940 47.66

Q75% 705 21.30

Q50% 470 6.84

24

Control factor: VFD - Calculations

• Assuming the motor is a 95% efficient motor (as before) and the drive is 96% efficient, the controlled PER (PERc) is then:

• The Load Control Factor that would be applied to all pumps is a ratio of the uncontrolled PER (bare pump + motor) to the controlled PER:

𝑷𝑬𝑹𝒄 = 𝟏 ∗𝟎. 𝟐𝟓 𝟕. 𝟗𝟒 𝒉𝒑 + 𝟎. 𝟐𝟓 𝟐𝟐. 𝟕𝟖 𝒉𝒑 + 𝟎. 𝟐𝟓 𝟓𝟎. 𝟏𝟓 𝒉𝒑 + 𝟎. 𝟐𝟓 𝟓𝟑. 𝟑𝟎 𝒉𝒑

𝟎. 𝟗𝟔

𝑷𝑬𝑹𝒄 = 𝟑𝟓. 𝟏𝟓 𝒉𝒑

𝑷𝑬𝑹𝒄

𝑷𝑬𝑹=

𝟑𝟓. 𝟏𝟓

𝟒𝟓. 𝟎𝟖

𝑳𝑪𝑭 = 𝟎. 𝟕𝟖

25

Control factor: Two Speed Motor

• Based on bare pump input power at BEP, nameplate motor efficiency, motor loss curves, and rated speeds (low and high speed): – Assume for this calculation that low speed is ½ of

high speed

Load Point Rated Speed (RPM) Power (hp) % Motor Load

Q110% 1750 53.30 84%

QBEP 1750 50.15 79%

Q75% 1750 42.32 67%

Q50% 875 7.94 11% (54%)

𝑷𝟏

𝑷𝟐=

𝒏𝟏

𝒏𝟐

𝟐.𝟖

=𝑸𝟏

𝑸𝟐

𝟐.𝟖

𝑷𝟎.𝟓𝟎 = 𝟓𝟎. 𝟏𝟓 𝒉𝒑𝟖𝟕𝟓 𝑹𝑷𝑴

𝟏𝟕𝟓𝟎 𝑹𝑷𝑴

𝟐.𝟖

= 𝟕. 𝟗𝟒

26

Control factor: Two Speed Motor - Calculations

• Assuming the motor is a 95% efficient motor (as before), the controlled PER (PERc) is then:

• The Load Control Factor that would be applied to all pumps a ratio of the uncontrolled PER (bare pump + motor) to the controlled PER:

𝑷𝑬𝑹𝒄 = 𝟎. 𝟐𝟓 𝟕. 𝟗𝟒 𝒉𝒑 + 𝟎. 𝟐𝟓 𝟒𝟐. 𝟑𝟐 𝒉𝒑 + 𝟎. 𝟐𝟓 𝟓𝟎. 𝟏𝟓 𝒉𝒑 + 𝟎. 𝟐𝟓 𝟓𝟑. 𝟑𝟎 𝒉𝒑

𝑷𝑬𝑹𝒄 = 𝟑𝟖. 𝟒𝟑 𝒉𝒑

𝑷𝑬𝑹𝒄

𝑷𝑬𝑹=

𝟑𝟖. 𝟒𝟑

𝟒𝟓. 𝟎𝟖

𝑳𝑪𝑭 = 𝟎. 𝟖𝟓

27

Two Speed Motor Issues

• Assumes lower speed is initiated at ~60% loading

• For other than 2-1 windings, could calculate P0.50 based on

actual low speed ratio 𝑛2

𝑛1 for motor to determine LCF for

each motor up to 2-1 – A conservative assumption could be P0.50=P(Q@n2), which is on system

curve

Motor Loading vs. Motor Size

55 hp 60 hp 75 hp

59.4% 54.4% 43.5%

73.0% 66.9% 53.5%

86.6% 79.4% 63.5%

92.1% 84.4% 67.5%

28

Control factor: Issues

• Issues: – Other control options to be considered?

• Desirable to make technology neutral?

– Not possible to distinguish similar control options

– Account for efficiency of control?

• Default efficiency value should use a conservative estimate

• Allow for differentiation based on improved efficiency in controls?

29

PER Calculation Comparison Summary

• PER accounts for savings from control and from more efficient motor

Equipment Configuration PER

Bare Pump 45.76

Pump + 95% Eff. Motor 45.08

Pump + Motor + VSD 35.15

Pump + 2-speed Motor 38.43

30

Bare Pump + Motor – Test Method

• Referred to as “string test” in HI 14.6 – Test similar to bare shaft test procedure,

except motor input power (Pin,i) is measured directly

• If motor efficiency changes significantly from rated value, tested PER will vary from calculated value

MOTOR PUMP


pump+motor combo.

standardized controls performance

Controls ×

Pump+motor performance data from pump test at

rated speed

𝑷𝑬𝑹 = 𝑳𝑪𝑭 𝝎𝟎.𝟓𝟎 𝑷𝒊𝒏,𝟎.𝟓𝟎 + 𝝎𝟎.𝟕𝟓 𝑷𝒊𝒏,𝟎.𝟕𝟓 + 𝝎𝑩𝑬𝑷 𝑷𝒊𝒏,𝑩𝑬𝑷 + 𝝎𝟏.𝟏 𝑷𝒊𝒏,𝟏.𝟏

31

pump performance from pump test at rated and reduced speed

× motor/drive performance

data

B

C

VFD MOTOR

Controls MOTOR PUMP

Bare Pump + Motor + Controls

Manufacturer can pair its pump data

with tested motor+VFD data.



× manufacturer or default

motor efficiency

A MOTOR


motor data and default controls

credits. pump performance

data from pump test at rated speed

default controls performance

Controls ×

32

Calculation is similar to pump + motor approach, but use combined

efficiency of motor + drive as determined by AHRI 1210:

Drive system efficiency determined through interpolation of AHRI 1210-

tested points:

Determining Bare Pump + Motor + Controls Performance – AHRI 1210

Speed/ Torque Points

16% 25% 56% 100%

40% 85% 88%

50% 91% 92%

75% 93% 95%

100% 98%


𝑷𝟎.𝟓𝟎

η𝒅𝒓𝒊𝒗𝒆,𝒎𝒆𝒂𝒔+ 𝝎𝟎.𝟕𝟓

𝑷𝟎.𝟕𝟓

η𝒅𝒓𝒊𝒗𝒆,𝒎𝒆𝒂𝒔+ 𝝎𝑩𝑬𝑷

𝑷𝑩𝑬𝑷

η𝒅𝒓𝒊𝒗𝒆,𝒎𝒆𝒂𝒔+ 𝝎𝟏.𝟏

𝑷𝟏.𝟏

η𝒅𝒓𝒖𝒗𝒆,𝒎𝒆𝒂𝒔

33

Determining Bare Pump + Motor + Controls Performance – AHRI 1210

Linearly interpolate points from AHRI to pump load points For example for P0.75 and assuming a 60 hp motor/VFD with a rated full

load speed of 1800 RPM:

Load Point Rated Speed (RPM) Torque (lb-in) Bare Pump Input Power (hp)

Q110% 1750 1783 50.65

QBEP 1750 1721 47.66

Q75% 1312.5 1459 21.30

Q50% 875 1112 6.84

Speed/ Torque Points

352 lb-in 550 lb-in 1232 lb-in 2200 lb-in

720 RPM 85% 88%

900 RPM 91% 92%

1350 RPM 93% 95%

1800 RPM 98%

34

Interpolating AHRI 1210 Drive Efficiencies

• Select the speed/torque point closest to the P0.75 load point

• For the speed adjustment:

– Select the higher and lower speed/torque points:

η𝒅𝒓𝒊𝒗𝒆,𝟎.𝟕𝟓 =η𝒅𝒓𝒊𝒗𝒆,𝑨𝑯𝑹𝑰,𝒏𝟕𝟓% − η𝒅𝒓𝒊𝒗𝒆,𝑨𝑯𝑹𝑰,𝒏𝟓𝟎%

𝒏𝑨𝑯𝑹𝑰,𝒏𝟕𝟓% − 𝒏𝑨𝑯𝑹𝑰,𝒏𝟓𝟎%(𝒏𝟎.𝟕𝟓−𝒏𝑨𝑯𝑹𝑰,𝒏𝟕𝟓%) +

η𝒅𝒓𝒊𝒗𝒆,𝑨𝑯𝑹𝑰,𝝉𝟏𝟎𝟎% − η𝒅𝒓𝒊𝒗𝒆,𝑨𝑯𝑹𝑰,𝝉𝟓𝟔%

𝝉𝑨𝑯𝑹𝑰,𝝉𝟏𝟎𝟎% − 𝝉𝑨𝑯𝑹𝑰,𝝉𝟓𝟔%(𝝉𝟎.𝟕𝟓 − 𝝉𝑨𝑯𝑹𝑰,𝒏𝟓𝟔%) +

η𝒅𝒓𝒊𝒗𝒆,𝑨𝑯𝑹𝑰,𝒏𝟕𝟓%

η𝒅𝒓𝒊𝒗𝒆,𝟎.𝟕𝟓 =𝟗𝟑% − 𝟗𝟏%

𝟏𝟖𝟎𝟎 − 𝟏𝟑𝟓𝟎𝟏𝟑𝟏𝟐. 𝟓 − 𝟏𝟑𝟓𝟎 +

𝟗𝟖% − 𝟗𝟑%

𝟐𝟐𝟎𝟎 − 𝟏𝟐𝟑𝟐𝟏𝟒𝟓𝟗 − 𝟏𝟐𝟑𝟐 + 𝟗𝟑%

= 𝟗𝟒%

35

Interpolating AHRI 1210 Drive Efficiencies

• Applying this for both speed and torque and for all load points:

• Note reduced speed pump input power data is applied – Could be physically tested or assumed using pump affinity laws

𝑷𝑬𝑹 = 𝟎. 𝟐𝟓 𝟓𝟒. 𝟑𝟗 + 𝟎. 𝟐𝟓 𝟓𝟏. 𝟏𝟖 𝒉𝒑 + 𝟎. 𝟐𝟓 𝟐𝟒. 𝟒𝟓 𝒉𝒑 + 𝟎. 𝟐𝟓 𝟖. 𝟕𝟒 𝒉𝒑

𝑷𝑬𝑹 = 𝟑𝟒. 𝟎𝟒 𝒉𝒑

36

• Can be harmonized with HI 40.6 method of test to determine PER for extended products – 40.6 focuses on pump efficiency determination by measuring both brake

hp and pump hydraulic power output – AHRI 1210 can be used to rate the part load efficiency of combined drive

system

• Proposed speed/torque loading is in line with system curve proposed in PER calculation method – Speed torque load profile is quadratic: 50% of synchronous speed

corresponds to 25% full load torque

• Tolerances are more stringent than HI 40.6 on both input and output side

• Issues: – AHRI 1210 may not be ready in time – How to apply to other drive types (e.g. engines)? – If standard is set using full load efficiency for motors, there may be an

inherent penalty to this method (although still would come out better)

AHRI 1210: Details & Issues

37

• Also known as “string” test, addressed in appendices as an non-mandatory method in HI 14.6

• Potential measurement method: – Measure input power to VFD terminals using same protocol as AHRI 1210 as applicable

(need to consider HI 11.6 for submersible pumps in order to address underwater electrical power measurements)

– Measure output hydraulic power using HI 40.6

• Due to nature of VFD control method, harmonics affect efficiency of drive system such that drive system efficiency is not same as product of individual motor and VFD efficiencies

• Could be applied to some pump types (e.g. submersibles and circulators) only

Determining Bare Pump + Motor (+ Controls) Performance – Wire-to-Water Testing

Controls MOTOR PUMP



38

PER Comparison Summary Using Test Methods

• Testing:

• Calculation:



Pump + Motor + VSD – AHRI 1210 34.04

Pump + Motor + VSD – Wire-to-Water 33.83


Bare Pump 45.76


Pump + Motor + VSD 35.15

Pump + 2-speed Motor 38.43

39

Applicable Test Methods

• Should manufacturers have the option to test or should the calculation method be required?

• Is physical testing more appropriate for some equipment classes while a calculation method is more appropriate for others?

Test Method Pros Cons

Calculation Method

Repeatable; Less burdensome

Does not differentiate different controls performance; Assumptions regarding change in motor/controls efficiency with changing load required; Decreased accuracy

Physical Test Method

Accurate; Differentiates performance of different motor/controls equipment at full and part load

Burdensome; AHRI 1210 test data not available;

40

Options for the PER metric load points could include:

• 50%, 75%, 100%, and 110% of BEP flow

• 75%, 100%, and 110% of BEP flow

• Others?

25% of BEP flow

• Some pumps may have difficulty or not be able to operate at the 25% load point without controls (i.e. with throttling)

• Exaggerates improved performance with controls due to low loading

110% of BEP flow

• This point is part of the EU “house of efficiency,” designed to encourage a broad efficiency curve

PER Load Point Choice


𝑷𝟎.𝟓𝟎


𝑷𝟎.𝟕𝟓

η𝒎𝒐𝒕𝒐𝒓,𝒅𝒆𝒇𝒂𝒖𝒍𝒕+ 𝝎𝑩𝑬𝑷

𝑷𝑩𝑬𝑷


𝑷𝟏.𝟏


41

• Load points assuming equal weighting:

• Choice of load points does not impact ranking, only relative magnitude – Less lower load points de-emphasizes impact of controls

Impact of Different Load Points

Load profile

Pump Energy Rating (PER) in hp

Bare pump

Pump & Motor

Control Options

VFD 2-Speed

25%, 50%, 75%, 100% of BEP flow 39.05 38.44 21.97 28.34

50%, 75%, 100%, 110% of BEP flow 45.76 45.08 35.15 38.43

Constant load at 25% 27.25 26.77 2.76 1.95

Constant load at 100% 50.90 50.15 52.23 50.15

42

Normal Load Curve

• Assume normal curve stretches from 0% of BEP flow to 120% of BEP flow

• Could select specific values (red diamonds) or bin weights into ≤50%, ≤75%, ≤100%, and <100% (green boxes).

0

0.005

0.01

0.015

0.02

0.025

0 10 20 30 40 50 60 70 80 90 100 110 120

We

igh

t V

alu

e

% of BEP Flow

43

• Assume load points of 50%, 75%, 100% and 110% of BEP flow:

Impact of Different Weightings

Load profile

Pump Energy Rating (PER) in hp

Bare pump

Pump & Motor

Control Options

VFD 2-Speed

Equal weighting 45.76 45.08 35.15 38.42

Normal Load Curve (Discrete) 40.00 39.38 19.52 26.47

Normal Load Curve (Bins) 42.39 41.75 25.76 36.84

0

0.1

0.2

0.3

0.4

0.5

0.6

50 75 100 110

We

igh

t V

alu

e

% of BEP Flow

Normalized Discrete

Normalized Bins

Equal Weight

44

PER Options

No Denominator Denominator

Form Weighted average of pump input power at several load points

Weighted input of pump input power at several load points normalized by pump hydraulic output power, a reference pump efficiency, or other value

Units kW, Btu, or HP Dimensionless*

Standard Strong function of flow and specific speed

Weak function of flow and specific speed

Pros Representative of the energy consumption of that pump in the field

More comparable across pumps of different sizes/specific speeds; Similar to EEI approach in EU

Cons Not comparable across pumps of different flows/specific speeds

No reference pump efficiency in US, so difficult to set; other denominator options may not be logical (discussed on next slide)

*May vary based on denominator chosen

45

Denominator Options Denominator Pros Cons

Power consumption of same pump in an uncontrolled system

N/A

This value gives no indication of the efficiency of the pump - two pumps with equivalent part-load performance and different efficiencies at BEP would have the same rated value.

Reference shaft power for minimally compliant bare pump with minimally compliant motor

Results in value between 0 and 1. Clearly indicates performance of a pump relative to a baseline.

Inherently requires designation of minimally compliant pump (i.e., MEI). May over- or under-represent the baseline efficiency for some pumps.

Market average shaft power with minimally compliant or market average motor

Indicates performance of a pump relative to the market.

Locks in the metric to the performance of pumps in the market at a given point in time. Doesn’t limit metric values between 0 and 1.

Tested pump’s hydraulic power at BEP

Accounts for differences in pump efficiencies between models. Has similar rated values for pumps of different sizes

Lower PER rating for smaller pumps because lower capacity equipment is inherently less efficient.

46

Possible Denominator Scaling Options

• To determine the normalized PER using the various denominator options, scale the PER without a denominator as follows:

𝑃𝐸𝑅𝑁𝑜𝑟𝑚 =𝑃𝐸𝑅𝑂𝐿𝐷 (ℎ𝑝)

𝐷𝐸𝑁𝑂𝑀 (ℎ𝑝)

• For 50%, 75%, 100%, and 110% of BEP flow as load points and equal weighting:

Denominator

Scaling Options Value (hp)

Pump energy rating (PER)

Bare shaft pump

Pump & motor

Pump, motor & VFD

Hydraulic power 37.6 1.219 1.200 0.936

Shaft Power 47.6 0.960 0.946 0.738

Minimally Compliant

(MEI10) 64.4 0.711 0.710 0.514

Market Average (MEI50)

59.3 0.7713 0.7712 0.558

Documents

ASRAC Pumps Working Group Metric: Calculations and