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Total System Efficiency when Specifying VFD’s for Sustainable BuildingsJohn ConboyDirector of Sales & Marketing – Drives MENA
The Facts
3 | Danfoss Drives | Energy Efficiency
20%of the world’s energy consumptionis electrical energy
50%of electrical energy is used byelectric motors
100%of electric motors are oversized
75%of electric motors are used on Variable Torque load
50%reduction of energy consumption for a 20% reduction of flow
20%of electric motors use a VFD for control
4 | Danfoss Drives | Energy Efficiency
8%of global electricity consumption by 2040
AC drives have the potential to save
The Science
6 | Danfoss Drives | Energy Efficiency
The Affinity Law
100
70
00 70 100
Flow
, %
Speed, %
N2 N1
Q1
Q2
100
49
00 70 100
Pre
ssu
re, %
Speed, %
N2 N1
P1
P2
100
34
00 70 100
Pow
er, %
Speed, %
N2 N1
HP1
HP2
Affinity Laws of Centrifugal Loads:
FLOW is a proportional to motor speed
PRESSURE is proportional to the motor speed squared
POWER is proportional to the motor speed cubed
N = Speed
Q = Flow
P = Pressure
HP = Horsepower
Q2
Q1
N2
N1=
P2
P1
N2
N1=
2HP2
HP1
N2
N1=
3
7 | Danfoss Drives | Energy Efficiency
Pump control methods
Source of images: https://www.linkedin.com/pulse/comparison-different-flow-control-methods-pumps-mircea-tomescu/
Flow Control Methods
8 | Danfoss Drives | Energy Efficiency
Fan control methods Flow Control Methods
Outlet Damper Inlet Box Damper Variable Inlet Vane Variable Frequency Drive
% Design Flow%
Des
ign
KW
120
100
80
60
40
20
040 50 60 70 80 9030 100
9 | Danfoss Drives | Energy Efficiency
Why do we do this?
The Standards
11 | Danfoss Drives | Energy Efficiency
Definitions according to IEC61800-9
Extended Product
Motor System
Power Drive System (PDS)
Motor Starter(Contactor, Softstarter,…)
Trans-mission
Driven Equipment
Load-machine
Mains & cabling
Complete Drive Module (CDM)
Often named as VSD (Variable Speed Drive)
Feedingsection
Aux-ilaries
BasicDrive
Module (BDM)
12 | Danfoss Drives | Energy Efficiency
Ecodesign from around the world
• Ecodesign is an approach to designing products with special consideration for the environmental impacts of the product during its whole lifecycle – it includes but is not limited to energy efficiency
• Around the world, various countries implement eco-design policies for motor systems
• The requirements are called MEPS (Minimum Efficiency Performance Standard)
13 | Danfoss Drives | Energy Efficiency
Classification of motors and drives
IEC/EN 60034-30-1
• Fixed speed motors (DOL)• Classes IE1 – IE4
IEC/EN 60034-30-2
• Variable speed operation• Classes IE1 – IE5
IEC/EN 61800-9-2
• Complete Drive Module (CDM)• Classes IE0 – IE2
IEC/EN 61800-9-2
• Power Drive System (PDS)• Classes IES0 – IES2
Motor
Drive
Drive + motor
14 | Danfoss Drives | Energy Efficiency
Part load losses
• Part load losses are defined in the nominal point and in 7 additional part load points for:
• CDM (drive)• PDS (drive + motor)
• Note that the nominal point for drives is 90% of nominal load and 100% for systems
• Part load losses can be determined in any point by interpolating between the 8 standardized points
Relative torque [%]
0%0% 100%
100%
50%
25%
50%
Relative speed [%]
CDM
PDS
Relative torque producing current [%]
0%0% 90%
100%
50%
25%
50%
Relative motorstator frequency
[%]
Arbitrary load point
15 | Danfoss Drives | Energy Efficiency
Extended product approach
• The extended product approach combines the losses or efficiency of the motor system with the losses/efficiency of the driven system (pump, fan, conveyor, etc.)
• Based on the losses or efficiency of the extended product, the energy efficiency index (EEI) can be calculated for a given load-time duty profile
• Knowing the part load losses for the motor-drive system is essential for calculating the EEI, which is the ultimate purpose of the ecodesign standard
The products that will affect Total System Efficiency
The Motor
17 | Danfoss Drives | Energy Efficiency
Comparison of efficienciesVentilation Unit with IE2, IE3 and IE4 motor
The products that will affect Total System Efficiency
The Fan
19 | Danfoss Drives | Energy Efficiency
Comparison test – same installationAir Handling Unit, manufactured by Trubel Luft-und Klimatechnik GmbH
AHU w. Radial Fan (Plug Fan) AHU w. High Efficiency Axial Fan
Radial Fan (Plug fan)High Efficiency Axial Fan
20 | Danfoss Drives | Energy Efficiency
Energy cost saving
Energy SavingHigh Efficiency Axial Fan vs. Radial Fan (Plug Fan)
The products that will affect Total System Efficiency
The DriveInstalled Efficiency
Heat lossHarmonics
22 | Danfoss Drives | Energy Efficiency
Input:kW System
++
+ +
Installed or “wire to air” or “wire to water” efficiency is the trend:
Motor/AC drive CAPEX/OPEX split
Investment
Electricity
Harmonic mitigation
AC unit
Installed energy efficiency is important
23 | Danfoss Drives | Energy Efficiency
110 kW 50 Hz, 4 pole motor:• IE 1 = 93,3 %• IE 2 = 94,5 %• IE 3 = 95,4 %
Energy efficiency difference for a 110 kW IE 2 vs IE 3 motor is 0,9 %, price ~15-20 % - 0,9 % efficiency gain seems important !
Which item of efficiency is most important?
24 | Danfoss Drives | Energy Efficiency
There are many solutions:
• Low Harmonic Drive - AAF based
• Low Harmonic Drive – AFE based
• Central/Sep. solutions – AAF based
• Passive Harmonic solutions
Heatloss/efficiency difference between AAF vs AFE
0
10,000
20,000
30,000
40,000
50,000
AQUA AAF
NXC AFE
Heat loss W
PowerSize
Energy Efficiency harmonic mitigation
25 | Danfoss Drives | Energy Efficiency
Additional benefits for AAF:
• AAF sleep mode saves energy
• If the AAF fails, the drive will continue
• The AAF creates lower boost voltage and less motor stress than the AFE
Power Heat Loss W AAF/AFE Size kW AAF AFE Difference conv. to efficiency
160 8.725 11.356 2.631 1,6%200 9.831 13.731 3.900 2,0%250 11.371 18.753 7.382 3,0%355 15.320 23.610 8.290 2,3%400 17.180 26.166 8.986 2,2%450 18.447 29.986 11.539 2,6%500 21.909 33.768 11.859 2,4%560 24.592 38.241 13.649 2,4%630 26.640 40.574 13.934 2,2%710 30.519 46.524 16.005 2,3%
Comparison of heat loss at <5% THD
26 | Danfoss Drives | Energy Efficiency
Typically 0.4W of energy needed to remove 1W of heat.
The energy saving for a 160 kW drive will be about 15 % of investment made in standard AC drive
90%
160 kW AC drive standard: Heatloss 3770 W. AC saving ~ 3770 * 0,9 * 0,4 AC * 0,1 € * 0,6 load * 24 h * 365 d = 713 € ~ 15 % of AC drive purchase price
Intelligent heat managementPart of installed efficiency
90%Reduction in energy use
for air condition
27 | Danfoss Drives | Energy Efficiency
0.0%
0.5%
1.0%
1.5%
2.0%
2.5%
3.0%
3.5%
160 200 250 355 400 450 500 560 630 710
conv. to eff.
AC Eff saving
0.0%
5.0%
10.0%
15.0%
20.0%
25.0%
30.0%
35.0%
40.0%
45.0%
160 200 250 355 400 450 500 560 630 710
Total
Heat loss AAF/AFE
AC saving
Efficiency % gain
Power size
Power size
Basis for calculations: LHD AC Drive, 0,1 €/kWh, 60 % load, 24/7 operation, 0,4 W AC/W removed
Options Efficiency gained
IE 2 to IE 3 motor 0,9 %
Backchannel cooling ~ 2,5 %
AAF vs AFE 1,6 – 3,0 %
Options Savings % of Inv.
Backchannel cooling 12 – 20 %
AAF vs AFE 7 – 23 %
Total 20 – 43 %
% Savings per year/Inv. in AC drive
Which item of efficiency is most important?
The Summary
29 | Danfoss Drives | Energy Efficiency
Summary
• Consider Energy Efficiency in all parts of your HVAC Systems
• Specify high efficient Drive and Motor Systems to meet IEC/EN 61800-9-2 Class IES2 and capability for more motor technologies with same drive (future proof)
• Specify highest efficiency fans, pumps and compressors
• Apply an Extended Product Approach and Specify Energy Efficiency Index• Utilize intelligent Heat Management e.g. Back-Channel Cooling.
• There are no regulations, which require THDi ≤ 5% at drive mains terminals.
• Apply IEEE-519 recommended limits at the PCC only and not to individual pieces of equipment.
• Do not use harmonics mitigation equipment, if it is not needed.
THANK YOUFOR ATTENDING THE PRESENTATION
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