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
โข Calculation-based method
- How to account for motor efficiency at part load and controls
โข Testing-based method
Load point options
โข Vote?
Weighting options
โข 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
โPumpโ Efficiency or Energy Use =
5
Possible Metric
Pump Energy Rating (PER): equally weighted average electric input power (P1) to the โpumpโ 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).
โข For bare pump or pump+driver, achieve part-load by throttling through pump curve at rated speed.
โข 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 โข Metric
โ Denominator
โข Motor losses โ bring examples to 3/26 meeting
โ Full load only, different loss curves for different types of motors?
โข Method to account for controls โ bring examples to 3/26 meeting โ Testing for drive efficiency? โ Load Control Factor to account for different types: VSD, multi-speed motors,
ECMs?
โข Load points (i) - % of BEP flow โ 50%, 75%, 100%? โ 25%, 50%, 75%, 100%? โ 75%, 100%, 110%? โ 50%, 75%, 100%, 110%?
โข Weighting (wi)
โ Equal weighting? (w=0.25)
๐ท๐ฌ๐น = ๐ณ๐ช๐ญ
๐๐.๐๐๐ท๐.๐๐
ฮท๐๐๐๐๐,๐ ๐๐๐๐๐๐+ ๐๐.๐๐
๐ท๐.๐๐ฮท๐๐๐๐๐,๐ ๐๐๐๐๐๐
+ ๐๐ฉ๐ฌ๐ท๐ท๐ฉ๐ฌ๐ท
ฮท๐๐๐๐๐,๐ ๐๐๐๐๐๐+ ๐๐.๐
๐ท๐.๐ฮท๐๐๐๐๐,๐ ๐๐๐๐๐๐
๐ท๐ฏ๐๐ ๐๐
7
Metric Options
โข PER
โข MEI โ describes pump only
โข EEI โ describes impact of controls only
โข gpm / kWh for electric pump/driver combinations
โข gpm / Btu for non-electric pump/driver combinations
โข kWh / gpm for electric pump/driver combinations
โข Btu / gpm for non-electric pump/driver combinations
โข kWh / (gallons or gpm * feet of head) for electric pump/driver combinations
โข Btu / (gallons or gpm * feet of head) for non-electric pump/driver combinations
8
Calculation methods
โข Bare shaft pump
โข Bare pump sold with motor
โข Bare pump sold with motor and control (VFD)
Test methods
โข Bare pump sold with motor
โข 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: โข Rated Flow: 900 GPM โข Rated Head: 160 ft โข 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%)
โข 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
โข Hydraulic pump efficiency is calculated at each flow point
โ Input power = (torque) x (speed)
โ Output power = (flow rate) x (head) x (specific weight of fluid)
โ Efficiency = output power / input power
โข 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) ฮท (%)
ฮท [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
ร standardized motor
efficiency (and part load curve?)
MOTOR
pump performance data from pump test at rated
speed
Bare Pump
ร standardized controls
performance
Controls
โข Standard motor: AC Induction, NEMA Design B, open enclosure. โข HP used will be next HP above brake horsepower at 120% of BEP HP. โข Poles will be based on speed at which pump is being rated.
Issues โข Standardized Motor Performance
โข Standard full load motor efficiency for all points, based on Federal standards; or โข Develop standard motor part-load curves.
โข Standardized Controls Performance โข Assume 100% efficiency; or โข Develop standard control efficiency, potential with part-load curves.
12
Determining Bare Pump Performance
โข Determine brake hp at Q50%, Q75%, Q100% and Q110% flow rates
โ 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
๐ท๐ฌ๐น = ๐ณ๐ช๐ญ ๐๐.๐๐
๐ท๐.๐๐
ฮท๐๐๐๐๐,๐ ๐๐๐๐๐๐+ ๐๐.๐๐
๐ท๐.๐๐
ฮท๐๐๐๐๐,๐ ๐๐๐๐๐๐+ ๐๐ฉ๐ฌ๐ท
๐ท๐ฉ๐ฌ๐ท
ฮท๐๐๐๐๐,๐ ๐๐๐๐๐๐+ ๐๐.๐
๐ท๐.๐
ฮท๐๐๐๐๐,๐ ๐๐๐๐๐๐
๐ท๐ฌ๐น = ๐ณ๐ช๐ญ ๐. ๐๐๐๐. ๐๐ ๐๐
ฮท๐๐๐๐๐,๐ ๐๐๐๐๐๐+ ๐. ๐๐
๐๐. ๐๐ ๐๐
ฮท๐๐๐๐๐,๐ ๐๐๐๐๐๐+ ๐. ๐๐
๐๐. ๐๐ ๐๐
ฮท๐๐๐๐๐,๐ ๐๐๐๐๐๐+ ๐. ๐๐
๐๐. ๐๐ ๐๐
ฮท๐๐๐๐๐,๐ ๐๐๐๐๐๐
13
Accounting for Motor Losses
โข Full load motor efficiency (ฮทmotor,default) for the bare shaft pump PER calculation obtained from Table 3 in 10 CFR 431.25 (subpart B) โ Determine pump shaft hp at 120% of BEP flow = 1128 GPM = 53.65 hp -> 60 hp
โ For a four pole motor with rated load of 60 hp, the full load efficiency ฮทrated
DOE = 93.6%
โข To account for motor losses with decreased loading, one could calculate motor losses at each load point based on a load fraction: โ Calculate load fraction (brake hp at each load point
divided by rated motor load [60 hp])
โข 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: โ yi = 0.12xi
3 + 0.18xi2 + 0.4xi +0.3
โข Where yi is the loss factor at each load point (i), and xi is the load fraction for each load point
๐๐ =๐ท๐
๐ด๐๐๐๐๐บ๐๐๐[๐๐]=
๐ท๐
๐๐ ๐๐=
๐๐. ๐๐
๐๐= ๐. ๐๐๐
14
Accounting for Motor Losses
โข Calculate the fractional load loss at each flow point using: ๐ฟ๐ = ๐ฟ๐๐ข๐๐,๐๐๐ก๐๐ โ ๐ฆ๐
โ 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
โข Calculate the fractional input power as follows: ๐๐๐๐ = ๐๐ + ๐ฟ๐
โ 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)
โ 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
โข Calculate PER by weighting each of the input power values as follows:
โข Assume standardized load control factor of 1.
๐ท๐ฌ๐น = ๐ณ๐ช๐ญ ๐. ๐๐ ๐๐. ๐๐ ๐๐ + ๐. ๐๐ ๐๐. ๐๐ ๐๐ + ๐. ๐๐ ๐๐. ๐๐ ๐๐ + ๐. ๐๐ ๐๐. ๐๐ ๐๐
๐ท๐ฌ๐น = ๐๐. ๐๐ ๐๐
16
Motor Losses Equation
โข Motor loss curves based on Motor Masters Database
โข Different load loss curves for ODP/TEFC and 2-pole/4-pole motors
โข 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
ร 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 ร
MOTOR PUMP
Manufacturer can measure power of
pump+motor combo.
standardized controls
performance
Controls ร
motor/drive performance data
B
A
18
Determining Bare Pump + Motor Performance โ Calculation Method
โข Calculate PER using the same method as for the bare shaft pump except:
โ Incorporate the rated motor efficiency rather than DOE minimum efficiency
โข Assume 60 hp motor with ฮทmotor,meas = 95% (Lfull,rated = 3.16 hp) and other values as before:
๐ท๐ฌ๐น = ๐ณ๐ช๐ญ ๐๐.๐๐
๐ท๐.๐๐
ฮท๐๐๐๐๐,๐๐๐๐+ ๐๐.๐๐
๐ท๐.๐๐
ฮท๐๐๐๐๐,๐๐๐๐+ ๐๐ฉ๐ฌ๐ท
๐ท๐ฉ๐ฌ๐ท
ฮท๐๐๐๐๐,๐๐๐๐+ ๐๐.๐
๐ท๐.๐
ฮท๐๐๐๐๐,๐๐๐๐
๐ท๐ฌ๐น = ๐ โ ๐. ๐๐ ๐๐. ๐๐ ๐๐ + ๐. ๐๐ ๐๐. ๐๐ ๐๐ + ๐. ๐๐ ๐๐. ๐๐ ๐๐ + ๐. ๐๐ ๐๐. ๐๐ ๐๐
๐ท๐ฌ๐น = ๐๐. ๐๐ ๐๐
% 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
ร 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 can measure power of
pump+motor+ controls combo.
ร manufacturer or default
motor efficiency
A MOTOR
Manufacturer can pair its pump data with manufacturer
motor data and default factor for
controls. pump performance
data from pump test at rated speed
default controls performance
Controls ร
20
โข 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:
โข PER calculated for all three control options using : โ bare pump shaft input power at BEP flow,
โ motor nameplate efficiency, and
โ pump affinity laws
Determining Bare Pump + Motor + Controls Performance โ
๐ท๐ฌ๐น = ๐ณ๐ช๐ญ ๐๐.๐๐
๐ท๐.๐๐
ฮท๐๐๐๐๐,๐๐๐๐+ ๐๐.๐๐
๐ท๐.๐๐
ฮท๐๐๐๐๐,๐๐๐๐+ ๐๐ฉ๐ฌ๐ท
๐ท๐ฉ๐ฌ๐ท
ฮท๐๐๐๐๐,๐๐๐๐+ ๐๐.๐
๐ท๐.๐
ฮท๐๐๐๐๐,๐๐๐๐
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
โข ๐ฟ๐ถ๐น = ๐๐ธ๐ ๐ถ๐๐๐ก๐๐๐๐๐๐
๐๐ธ๐ ๐๐๐๐๐๐ก๐๐๐๐๐๐
โข 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:
โข 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
โข Account for motor losses in conservative LCF
Assumptions:
โข Efficiency of control = 96%
22
Control factor: VFD
โข Calculate PER using flow points along system curve, rather than using flow points along one constant speed pump curve (but no over-speeding)
โข The system curve is defined by the following pump affinity laws:
โข 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
๐ธ๐
๐ธ๐=
๐๐
๐๐
๐ฏ๐
๐ฏ๐=
๐๐
๐๐
๐.๐
๐ท๐
๐ท๐=
๐๐
๐๐
๐.๐
Reference System Curve H
Q
Q100% Q75% Q50%
H100%
Q110%
23
Control factor: VFD - Calculations
โข The flow at input power to the bare pump are available from the tested pump performance:
โข Using the pump affinity laws, the bare pump shaft input power at 75% of BEP flow (660 GPM) is:
โข Applied to all rating points yields the following:
๐ท๐ฉ๐ฌ๐ท = ๐๐. ๐ ๐ก๐ฉ; ๐ธ๐ฉ๐ฌ๐ท = ๐๐๐ ๐ฎ๐ท๐ด
๐ท๐
๐ท๐=
๐๐
๐๐
๐
=๐ธ๐
๐ธ๐
๐.๐
๐ท๐.๐๐
๐๐. ๐๐ ๐๐=
๐๐๐ ๐ฎ๐ท๐ด
๐๐๐ ๐ฎ๐ท๐ด
๐.๐
๐ท๐.๐๐ = ๐๐. ๐๐ ๐๐๐๐๐ ๐ฎ๐ท๐ด
๐๐๐ ๐ฎ๐ท๐ด
๐.๐
= ๐๐. ๐๐ ๐๐
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
โข Assuming the motor is a 95% efficient motor (as before) and the drive is 96% efficient, the controlled PER (PERc) is then:
โข 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:
๐ท๐ฌ๐น๐ = ๐ โ๐. ๐๐ ๐. ๐๐ ๐๐ + ๐. ๐๐ ๐๐. ๐๐ ๐๐ + ๐. ๐๐ ๐๐. ๐๐ ๐๐ + ๐. ๐๐ ๐๐. ๐๐ ๐๐
๐. ๐๐
๐ท๐ฌ๐น๐ = ๐๐. ๐๐ ๐๐
๐ท๐ฌ๐น๐
๐ท๐ฌ๐น=
๐๐. ๐๐
๐๐. ๐๐
๐ณ๐ช๐ญ = ๐. ๐๐
25
Control factor: Two Speed Motor
โข Based on bare pump input power at BEP, nameplate motor efficiency, motor loss curves, and rated speeds (low and high speed): โ Assume for this calculation that low speed is ยฝ 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%)
๐ท๐
๐ท๐=
๐๐
๐๐
๐.๐
=๐ธ๐
๐ธ๐
๐.๐
๐ท๐.๐๐ = ๐๐. ๐๐ ๐๐๐๐๐ ๐น๐ท๐ด
๐๐๐๐ ๐น๐ท๐ด
๐.๐
= ๐. ๐๐
26
Control factor: Two Speed Motor - Calculations
โข Assuming the motor is a 95% efficient motor (as before), the controlled PER (PERc) is then:
โข The Load Control Factor that would be applied to all pumps a ratio of the uncontrolled PER (bare pump + motor) to the controlled PER:
๐ท๐ฌ๐น๐ = ๐. ๐๐ ๐. ๐๐ ๐๐ + ๐. ๐๐ ๐๐. ๐๐ ๐๐ + ๐. ๐๐ ๐๐. ๐๐ ๐๐ + ๐. ๐๐ ๐๐. ๐๐ ๐๐
๐ท๐ฌ๐น๐ = ๐๐. ๐๐ ๐๐
๐ท๐ฌ๐น๐
๐ท๐ฌ๐น=
๐๐. ๐๐
๐๐. ๐๐
๐ณ๐ช๐ญ = ๐. ๐๐
27
Two Speed Motor Issues
โข Assumes lower speed is initiated at ~60% loading
โข For other than 2-1 windings, could calculate P0.50 based on
actual low speed ratio ๐2
๐1 for motor to determine LCF for
each motor up to 2-1 โ 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
โข Issues: โ Other control options to be considered?
โข Desirable to make technology neutral?
โ Not possible to distinguish similar control options
โ Account for efficiency of control?
โข Default efficiency value should use a conservative estimate
โข Allow for differentiation based on improved efficiency in controls?
29
PER Calculation Comparison Summary
โข 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 โ Test Method
โข Referred to as โstring testโ in HI 14.6 โ Test similar to bare shaft test procedure,
except motor input power (Pin,i) is measured directly
โข If motor efficiency changes significantly from rated value, tested PER will vary from calculated value
MOTOR PUMP
Manufacturer can measure power of
pump+motor combo.
standardized controls performance
Controls ร
Pump+motor performance data from pump test at
rated speed
๐ท๐ฌ๐น = ๐ณ๐ช๐ญ ๐๐.๐๐ ๐ท๐๐,๐.๐๐ + ๐๐.๐๐ ๐ท๐๐,๐.๐๐ + ๐๐ฉ๐ฌ๐ท ๐ท๐๐,๐ฉ๐ฌ๐ท + ๐๐.๐ ๐ท๐๐,๐.๐
31
pump performance from pump test at rated and reduced speed
ร 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 can measure power of
pump+motor+ controls combo.
ร manufacturer or default
motor efficiency
A MOTOR
Manufacturer can pair its pump data with manufacturer
motor data and default controls
credits. pump performance
data from pump test at rated speed
default controls performance
Controls ร
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 โ AHRI 1210
Speed/ Torque Points
16% 25% 56% 100%
40% 85% 88%
50% 91% 92%
75% 93% 95%
100% 98%
๐ท๐ฌ๐น = ๐ณ๐ช๐ญ ๐๐.๐๐
๐ท๐.๐๐
ฮท๐ ๐๐๐๐,๐๐๐๐+ ๐๐.๐๐
๐ท๐.๐๐
ฮท๐ ๐๐๐๐,๐๐๐๐+ ๐๐ฉ๐ฌ๐ท
๐ท๐ฉ๐ฌ๐ท
ฮท๐ ๐๐๐๐,๐๐๐๐+ ๐๐.๐
๐ท๐.๐
ฮท๐ ๐๐๐๐,๐๐๐๐
33
Determining Bare Pump + Motor + Controls Performance โ 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
โข Select the speed/torque point closest to the P0.75 load point
โข For the speed adjustment:
โ Select the higher and lower speed/torque points:
ฮท๐ ๐๐๐๐,๐.๐๐ =ฮท๐ ๐๐๐๐,๐จ๐ฏ๐น๐ฐ,๐๐๐% โ ฮท๐ ๐๐๐๐,๐จ๐ฏ๐น๐ฐ,๐๐๐%
๐๐จ๐ฏ๐น๐ฐ,๐๐๐% โ ๐๐จ๐ฏ๐น๐ฐ,๐๐๐%(๐๐.๐๐โ๐๐จ๐ฏ๐น๐ฐ,๐๐๐%) +
ฮท๐ ๐๐๐๐,๐จ๐ฏ๐น๐ฐ,๐๐๐๐% โ ฮท๐ ๐๐๐๐,๐จ๐ฏ๐น๐ฐ,๐๐๐%
๐๐จ๐ฏ๐น๐ฐ,๐๐๐๐% โ ๐๐จ๐ฏ๐น๐ฐ,๐๐๐%(๐๐.๐๐ โ ๐๐จ๐ฏ๐น๐ฐ,๐๐๐%) +
ฮท๐ ๐๐๐๐,๐จ๐ฏ๐น๐ฐ,๐๐๐%
ฮท๐ ๐๐๐๐,๐.๐๐ =๐๐% โ ๐๐%
๐๐๐๐ โ ๐๐๐๐๐๐๐๐. ๐ โ ๐๐๐๐ +
๐๐% โ ๐๐%
๐๐๐๐ โ ๐๐๐๐๐๐๐๐ โ ๐๐๐๐ + ๐๐%
= ๐๐%
35
Interpolating AHRI 1210 Drive Efficiencies
โข Applying this for both speed and torque and for all load points:
โข Note reduced speed pump input power data is applied โ Could be physically tested or assumed using pump affinity laws
๐ท๐ฌ๐น = ๐. ๐๐ ๐๐. ๐๐ + ๐. ๐๐ ๐๐. ๐๐ ๐๐ + ๐. ๐๐ ๐๐. ๐๐ ๐๐ + ๐. ๐๐ ๐. ๐๐ ๐๐
๐ท๐ฌ๐น = ๐๐. ๐๐ ๐๐
36
โข Can be harmonized with HI 40.6 method of test to determine PER for extended products โ 40.6 focuses on pump efficiency determination by measuring both brake
hp and pump hydraulic power output โ AHRI 1210 can be used to rate the part load efficiency of combined drive
system
โข Proposed speed/torque loading is in line with system curve proposed in PER calculation method โ Speed torque load profile is quadratic: 50% of synchronous speed
corresponds to 25% full load torque
โข Tolerances are more stringent than HI 40.6 on both input and output side
โข Issues: โ AHRI 1210 may not be ready in time โ How to apply to other drive types (e.g. engines)? โ 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
โข Also known as โstringโ test, addressed in appendices as an non-mandatory method in HI 14.6
โข Potential measurement method: โ 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)
โ Measure output hydraulic power using HI 40.6
โข 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
โข Could be applied to some pump types (e.g. submersibles and circulators) only
Determining Bare Pump + Motor (+ Controls) Performance โ Wire-to-Water Testing
Controls MOTOR PUMP
Manufacturer can measure power of
pump+motor+ controls combo.
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PER Comparison Summary Using Test Methods
โข Testing:
โข Calculation:
Equipment Configuration PER
Pump + 95% Eff. Motor 44.95
Pump + Motor + VSD โ AHRI 1210 34.04
Pump + Motor + VSD โ Wire-to-Water 33.83
Equipment Configuration PER
Bare Pump 45.76
Pump + 95% Eff. Motor 45.08
Pump + Motor + VSD 35.15
Pump + 2-speed Motor 38.43
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Applicable Test Methods
โข Should manufacturers have the option to test or should the calculation method be required?
โข 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:
โข 50%, 75%, 100%, and 110% of BEP flow
โข 75%, 100%, and 110% of BEP flow
โข Others?
25% of BEP flow
โข Some pumps may have difficulty or not be able to operate at the 25% load point without controls (i.e. with throttling)
โข Exaggerates improved performance with controls due to low loading
110% of BEP flow
โข This point is part of the EU โhouse of efficiency,โ designed to encourage a broad efficiency curve
PER Load Point Choice
๐ท๐ฌ๐น = ๐ณ๐ช๐ญ ๐๐.๐๐
๐ท๐.๐๐
ฮท๐๐๐๐๐,๐ ๐๐๐๐๐๐+ ๐๐.๐๐
๐ท๐.๐๐
ฮท๐๐๐๐๐,๐ ๐๐๐๐๐๐+ ๐๐ฉ๐ฌ๐ท
๐ท๐ฉ๐ฌ๐ท
ฮท๐๐๐๐๐,๐ ๐๐๐๐๐๐+ ๐๐.๐
๐ท๐.๐
ฮท๐๐๐๐๐,๐ ๐๐๐๐๐๐
41
โข Load points assuming equal weighting:
โข Choice of load points does not impact ranking, only relative magnitude โ 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
โข Assume normal curve stretches from 0% of BEP flow to 120% of BEP flow
โข Could select specific values (red diamonds) or bin weights into โค50%, โค75%, โค100%, 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
โข 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. Doesnโt limit metric values between 0 and 1.
Tested pumpโs 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
โข To determine the normalized PER using the various denominator options, scale the PER without a denominator as follows:
๐๐ธ๐ ๐๐๐๐ =๐๐ธ๐ ๐๐ฟ๐ท (โ๐)
๐ท๐ธ๐๐๐ (โ๐)
โข 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