TYPES OF LOAD
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TYPES OF LOAD
CONSTANT TORQUE LOAD :
100
TORQUE
80
NOTE:A CONSTANT TORQUE LOAD
IS NOT NECESSARILY 100%
LOAD
50
50
100
PERCENT SPEED
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TYPES OF LOAD
CONSTANT TORQUE LOAD :
Positive Compressors
Displacement
Root
Conveyors
Blowers Pumps
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TYPES OF LOAD
VARIABLE TORQUE LOAD :
TORQUE & POWER IN %
100
80
TORQUE
60
40
POWER
20
0
10
20
30
40
50
60
70
80
90
100
SPEED IN %
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TYPES OF LOAD
VARIABLE TORQUE LOAD ( Torque Varies as Square of Speed)
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Centrifugal
CentrifugalPumps
Fans
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TYPES OF LOAD
CONSTANT HORSEPOWER LOAD :
100
TORQUE
HORSE POWER
TORQUE
50
50
100
150
200
PERCENT SPEED
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TYPES OF LOAD
CONSTANT HORSEPOWER LOAD :
• Lathe
• Grinders
• Winders
• Coilers
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ENERGY SAVING
APPLICATIONS
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Energy Savings
Key Applications Areas – The Energy Guzzlers
• Fans
– AHU
– Ventilation / Fresh Air
– Exhaust
– Cooling Tower Fans
– ID / FD Fans
• Pumps
– Process Water
– Pressure booster pumps
• Compressors
– Reciprocating, Screw,
Centrifugal
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FAN APPLICATION
Air flow control of fan
Outlet side
damper
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Inlet side
damper
10
Comparison of motor power for fan drive
system
100
0
50
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Airflow or motor speed
(%)
100
11
Flow Control-Affinity Laws
• Flow  Speed
• Pressure / Head  Speed 2
• Power  Speed 3
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Benefits of Flow Control…
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Fundamentals- Traditional
Throttle
Flow control is achieved by riding the pump or the fan curve…
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Fundamentals- Evolution
Flow control is achieved by riding the System Curve…
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PRINCIPLE - ENERGY SAVING BY
SPEED CONTROL OF PUMPS
A
E
THROTTLE CONTROL
ENERGY SAVING
B
PRESSURE
= SHADED REGION
= AREA (OEAD) - AREA (OFCD)
F
O
C
SPEED CONTROL
D
VOLUME
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The energy saving effect to the pump type
2.0
1.0
0
0.5
1.0
Flow rate Q (P.U.)
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PRINCIPLE - ENERGY SAVING BY
SPEED CONTROL
As Per Affinity Laws
Flow (%)
HP (%)
Required
100
100
75
42
50
12.5
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Compressors
• Operates in a load/ unload cycle.
Load
100%
Time
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Compressor–Load/Unload Control
Conventional compressor system work between two set
pressures, resulting in pressure generated being higher than
the pressure required in the system.
110PSI
PRESSURE
100PSI
20 PSI
90PSI
MINIMUM SYSTEM
PRESSURE REQUIRED
TIME
POWER
100% FULL LOAD POWER
DURING LOAD CYCLE
20-30% OF FULL LOAD POWER
DURING UNLOAD CYCLE
LOAD
UNLOAD
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TIME
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Disadvantages of Traditional Compressor:
 Energy consumption as high as 20-30% of full load
power during unload period.
 Pressure in the system is much more than the
minimum system pressure required, resulting in
extra power consumption and wear and tear of the
mechanical system.
 20PSI extra pressure in the system, results in 10%
extra power consumption.
 DOL or star/delta starting sequence on a motor
creates a power surge in electrical system.
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Typical Schematic
A
I
R
AC MOTOR
VARIABLE
SPEED
AC DRIVE
AIR
COMPRESSOR
PRESSURE
TRANSMITTER
R
E
C
E
I
V
E
R
To
Plant
4-20 mA/ 0-10V PRESSURE FEEDBACK SIGNAL
3 Ph./ 415V Supply
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Advantages with Inverter Control:
 Variable pressure setting possible.
 Accurate pressure control.
 No unload cycle, thus reducing power
consumption typically by 20 to 30% of full load
power.
 Soft start with inverter control, power to the
motor is increased progressively, avoiding peak
power demand in the electrical system.
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