1. Installing a variable speed drive (VSD) compressor can save around RM 32,746 per year in energy costs compared to a standard compressor. 2. A VSD compressor avoids idle times where 25-40% of motor power is consumed without producing air, blowdown times where air is wasted, and reduces pressure fluctuations which all contribute to energy savings. 3. By continuously matching compressor output to air demand using variable motor speed, a VSD compressor significantly reduces energy losses from idling, blowdown, pressure fluctuations and leakage compared to an on/off compressor.

1. Benefit of Variable Speed Unit

2. Compressed Air - 4th Utility After Electricity,
Natural Gas And Water
Expensive
Air is Free but Compressed Air is NOT !
• Lowering pressure by 1 bar (15 psi) reduces energy by 7%
• Lowering pressure by 1 bar (15 psi) reduces leakages by 13%
(artificial demand)

3. Benefit of Variable Speed Unit
Load / Unload Plant Air Consumption
0
8
14
80 160
Hours per week
Volumeflow
(m³/min)
• The Load / Unload control of a standard compressor causes in connection with fluctuating
compressed air demand expensive non-load times.
• During compressor unloading times, user have to pay 25 - 40% of the installed motor power
(e.g. for 75kW => 18.75 - 30kW) and does not produce any compressed air for it.

4. Benefit of Variable Speed Unit
If demand increases:
• Motor speed and therefore the speed of the airend is increased.
If demand decreases:
• Motor speed and therefore the speed of the airend is reduced.
VSD Technology

5. Benefit of Variable Speed Unit
Calculation Sample
Compressor Rating 75 kW (100HP)
Plant Utilization: 70% full load
 30% idling with approx. 25 - 40% full load consumption
Operating Hours/ Year 4.000 hours
Required Operating Pressure: 8 bar
Energy Cost (TNB) RM 0.337 / kWh
Main share
of savings
1. Idling Times Of The Compressors
2. Blow Down Times Of The Compressors
3. Compressed Air Losses During Blow Down
4. Pressure Bands Of The Compressors
5. Direct Output Losses In Producing Compressed Air
6. Leakage In The Compressed Air Network
Saving Potentials

6. Benefit of Variable Speed Unit
Calculation of the savings potential:
 4,000 hrs/yr x 30% idle share x 25% of 75 kW x electricity costs (RM/kWh)
1.200 kWh/yr x 18.75 kW x 0.337 (RM/kWh)
RM 7,582/ Year Savings
1. Idling Times Of The Compressors
25 - 40% of the energy – without producing any compressed air.
VSD - Technology
Traditional Load-idle
Operation
Drive
motor
consumption
(%)
Load Idle Load Idle
Example: 70% Capacity Utilisation
Energy
loss
100
90
80
60
40
30
20
10
70
50
0
Energy
loss
Idle operation: ca. 25%
Energy consumption
Saving Potentials

7. Benefit of Variable Speed Unit
Each time compressor switches between load and idle, average blow down 1 minute.
Calculation of the savings potential:
4,000 hrs/yr x 18.75 Load-Unload cycles/hr x 1 min. relief time
 75,000 minutes relief time = 1,250hr relief x 56.25/2 kW = 35,156 kWh
 35,156 kWh x RM 0.337/kWh
2. Blow Down Times Of The Compressors
VSD - Technology
Load Idle Load Idle
Example: blow down time 1 min
100
90
80
60
40
30
20
10
70
50
0
Energy loss
1 min
Drive
motor
consumption
(%)
56.25
kW
75 kW
18.75
kW
Saving Potentials
Traditional Load-idle
Operation
RM 11,847/ Year Savings

8. Benefit of Variable Speed Unit
Calculation of the savings potential:
4,000 hrs/year x 18.75 load-idle change/hr
 75,000 change/year x 360l compressed air loss = 27,000 m3 compressed air loss/year
 27,000 m³ compressed air loss/year x RM0.04*
P1 x V1 = p2 x V2
V2 =
p2
p1 x V1
9 barA x 80 l
V2 =
2 barA
V2 = 360 l (Comp. air loss per blow down)
* Average costs of compressed air: RM0.04 per m3
3. Compressed Air Losses During Blow Down
During blow down times, the compressed air is blown off until a small pressure level is
reached (eg. 2 barA)
Saving Potentials
RM 1,080/ Year Savings

9. Benefit of Variable Speed Unit
1 bar = 7% of Energy Cost
Calculation of the savings potential: ( 0.9 bar decrease of Pressure Range)
 0.9 x 7% of 75kW x 4.000 hr /Yr x RM 0.337/kWh
4. Pressure Bands Of The Compressors
VSD run at a constant operating pressure (p  0.1 bar).
Saving Potentials
VSD
RM 6,369/ Year Savings

10. Benefit of Variable Speed Unit
Efficiency V-belt Drive ~ 96 %
Efficiency Direct Drive ~ 99,9 %
Calculation of the savings potential:
75kW x 4% = 3.0 kW savings
 3.0kW x 4.000hr/Yr x RM 0.337 kW/hr
ŋ=96%
ŋ=99,9%
Direct
Belt
5. Direct Output Losses In Producing Compressed Air
(E.G. Direct Drive Compared To V-belt Drive)
Saving Potentials
RM 4,044/ Year Savings

11. Benefit of Variable Speed Unit
Calculation of the savings potential : (Pressure range reduction: 0.9 bar )
 25% leakage of 8.5m3/min = 2.125m3/min
 2.125m3/min leakage x 9% = 0.19m3/min decrease of leakage
 0.19m3/min x 4.000h = 45,600m3/year decrease of leakage
 45,600m3/year x RM0.04/m3
6. Leakage In Compressed Air Networks
• Compressed air pipes leakage.
• Studies have shown that the average rate of leakage in a compressed air station
is approx. 20-30%
• Lowering pressures by 1 bar , e.g. with speed control,
reduces leakage by approx. 10%
Saving Potentials
RM 1,824/ Year Savings

12. Benefit of Variable Speed Unit
Avoiding / reducing:
1. Idling Times: RM 7,582
2. Blow Down Times: RM 11,847
3. Air Losses During Blow Down: RM 1,080
4. Pressure Bands: RM 6,369
5. Direct Output Losses: RM 4,044
6. Leakage: RM 1,824
Total annual savings approx.: RM 32,746
by a VSD Technology
(compared to a standard compressor with 70% capacity utilization,
4000 hr/yr, energy costs RM 0.377/kWh )
Summary Of Total Savings:
Saving Potentials

13. Benefit of Variable Speed Unit
Savings on energy costs and maintenance:
• Many customers pay according to peak use  savings on energy costs
• Less burden on “weak“ power grids
• Less wear on mechanical parts
Smooth Start up Behaviour
VSD
Variable

14. Q & A

15. Thank You