Data Bulletin
Improve Operating Efficiency and Reduce Installed
Cost with Altivar™ 212 Adjustable Speed Drives
Retain for future use.
8800DB1201
02/2012
Introduction
The Altivar™ 212 adjustable speed drive operates more efficiently and
provides additional installed cost savings as compared to typical AC drives on
centrifugal pump and fan applications.
Applying AC drives on centrifugal pump and fan applications has been, and
continues to be, an excellent way to obtain energy savings and reduce
maintenance costs. By eliminating air flow dampers, inlet guide vanes, and
throttling valves—and by using an AC drive to control air and fluid flow—
users have reduced energy costs and maintenance costs.
Until now, AC drives from most manufacturers have provided similar rates of
energy savings by reducing the power the motor needs to provide optimum
flow. This bulletin describes the operating efficiency improvements and cost
savings that users can obtain by applying an Altivar 212 drive on centrifugal
pump and fan applications in place of typical AC drives, and the technology
designed into the Altivar 212 drive that provides these additional savings.
How Much Improvement in
Operating Efficiency Does the
Altivar 212 Drive Offer?
The Altivar 212 drive is able to provide a 3%–5% operating efficiency
improvement over typical AC drives on centrifugal pump and fan applications.
Based on typical duty cycle and energy costs, a 3%–5% improvement in
efficiency can save $120–$195 per year per drive when compared to typical
AC drives on a 15 hp motor. Figure 1 provides estimated energy costs of the
Altivar 212 drive, a typical AC drive, and operation with traditional contactor
control over a range of motor sizes.
Figure 1:
40,000
35,000
30,000
25,000
20,000
15,000
10,000
5,000
_
Altivar 212
Typical AC Drives
Without AC Drive
Estimated Annual Energy Costs
1
Dollars
5
10
15
20
25
30
Horsepower
50
75
1
Savings are based $0.09 / kWh; 7300 operating hours and a duty cycle of 100% speed for
1825 hours, 80% speed for 3650 hours, and 50% speed for 1825 hours.
© 2012 Schneider Electric All Rights Reserved
™
Improve Operating Efficiency and Reduce Installed Cost
with Altivar™ 212 Adjustable Speed Drives
8800DB1201
02/2012
Figure 2 shows the estimated reduction in energy costs of an Altivar 212 drive
compared to typical AC drives. Multiply the savings by the number of motors
and the annual savings offered by the Altivar 212 drive can be considerable.
Figure 2:
$1,000
$900
$800
$700
Dollars
$600
$500
$400
$300
$200
$100
$–
5
10
15
20
25
30
Horsepower
50
75
Estimated Annual Reduction in Energy Costs of an
Altivar 212 Drive Compared to Typical AC Drives
2
What is Different About
Altivar 212 Drive Technology?
The key design principles that enable the Altivar 212 drive to provide the
improvement in operating efficiency over typical AC drives used in pump
and fan applications are:
•
•
the unique, optimized power section, and
the engineering of the motor control algorithm and a powerful motor
control processor.
The power section design has been optimized by reducing the DC bus
capacitance value to approximately 3%–5% of the capacitor value of an
equivalent horsepower, typical AC drive. This modifies the input current
waveform characteristics by significantly reducing current spikes observed
during the capacitor charging cycle. Total input current draw is reduced,
lowering input current harmonics and input line RMS current values. This is
accomplished without AC line reactors, swinging chokes, or DC bus chokes
used by typical AC drives.
2
Savings are based $0.09 / kWh; 7300 operating hours and a duty cycle of 100% speed for
1825 hours, 80% speed for 3650 hours, and 50% speed for 1825 hours.
2
© 2012 Schneider Electric All Rights Reserved
8800DB1201
02/2012
Improve Operating Efficiency and Reduce Installed Cost
with Altivar™ 212 Adjustable Speed Drives
Figure 3 shows a typical input voltage and current waveforms of a 100 hp
6-pulse AC drive. The double-humped waveform shows the peak current
reaching 300 A as the capacitors charge.
Figure 3:
Typical AC Drive Input Waveform
Figure 4 shows typical input voltage and current waveforms of a 100 hp
Altivar 212 drive. Note the dramatic change in the shape of the input current
waveform. The current peaks only reach up to 190 A. Because of the
reduced capacitance, the input current is a square-shaped waveform,
eliminating the large, double-humped waveform which generates large
harmonic currents. This square-shaped current waveform produces lower
harmonic currents and lowers RMS input current.
Figure 4:
Altivar 212 AC Drive Input Waveform
By eliminating line reactors, swinging chokes, and DC bus chokes, the power
section has less resistance, which reduces energy losses and provides a
portion of the efficiency improvement offered by the Altivar 212 drive.
The second key design aspect of the Altivar 212 drive is the engineering of
the motor control algorithm and the powerful motor control processor used
to produce a smooth, sinusoidal waveform to the motor.
© 2012 Schneider Electric All Rights Reserved
3
Improve Operating Efficiency and Reduce Installed Cost
with Altivar™ 212 Adjustable Speed Drives
8800DB1201
02/2012
As there is less DC bus capacitance, there is more DC ripple on the DC bus.
The motor control algorithm and processor are engineered to manage this
ripple and produce a smooth, sinusoidal current waveform to the motor
suitable for powering motors on centrifugal pump and fan applications.
What are the Benefits of
Altivar 212 Drive Technology?
Three benefits of this technology are detailed below.
1. Harmonic reduction is equivalent to results obtained with line reactors,
swinging chokes, or DC bus chokes at a lower cost.
This technology provides harmonic mitigation without the use of line
reactors, swinging chokes, or DC bus chokes. Harmonic mitigation of
the Altivar 212 drive is equivalent to a typical AC drive with a line reactor,
swinging choke, or DC bus choke design. Eliminating these reactors and
chokes, and the space needed to mount them, can reduce the installed
cost by 4%–6% in a typical installation. See Schneider Electric Product
Data Bulletin 8800DB0702 for more information on the harmonic
mitigation benefits of the Altivar 212 drive and for a comparison of
harmonic mitigation techniques.
2. Reduction in input line current saves wiring cost and over current
protection device costs.
A benefit of the technology designed into the Altivar 212 drive is the
reduction of the input line current when compared to typical AC drives.
Figures 5 and 6 show the reduction in RMS current for a 15 hp drive.
Figure 5 shows a typical AC drive. It exhibits the double-humped
waveform as the capacitors charge. Note that the RMS current value is
20.53 A. Figure 6 shows the Altivar 212 drive. The waveform peaks are
much lower as the capacitors charge. Note that the RMS current value is
14.25 A, 30% less than the typical AC drive. The technology used in the
Altivar 212 drive results in lower RMS input currents by reducing high
peak current during the charging cycle.
Figure 5:
RMS Input Current of a Typical 15 HP AC Drive
4
© 2012 Schneider Electric All Rights Reserved
8800DB1201
02/2012
Improve Operating Efficiency and Reduce Installed Cost
with Altivar™ 212 Adjustable Speed Drives
Figure 6:
RMS Input Current of a 15 HP Altivar 212 Drive
Figure 7 illustrates input currents from several typical AC drives at different
horsepower sizes. As can be seen in the graph, the Altivar 212 drive has
lower input line current values. This lower input line current allows wire size
and over current protection devices to be sized accordingly smaller, often
reducing the total installed cost by 2%–4% compared to typical AC drives.
Figure 7:
Maximum Input Currents of the Altivar 212 AC Drive and
Other Typical AC Drives
Altivar 212
AC Drive A
AC Drive B
AC Drive C
AC Drive D
AC Drive E
160
140
120
100
Amps
80
60
40
20
0
3
5
7.5
10
15
20
25
30
40
50
60
75
100
Horsepower
3. Better power factor than typical AC drives improves operating efficiency.
Another benefit of the technology designed into the Altivar 212 drive that
contributes to its superior operating efficiency is the improvement in the
power factor when compared to typical AC drives. The Altivar 212 drive,
like most AC drives, converts incoming AC power to DC power using full
wave rectifiers. The optimized design of the input section and reduced
DC bus capacitance in the Altivar 212 drive converts AC power to
DC power more efficiently through the speed range, because the current
waveform is more in phase, or in step, with the voltage waveform when
compared to a typical AC drive design. In electric power systems, a load
with a low power factor draws more current than a load with a high
power factor for the same amount of useful power transferred.
© 2012 Schneider Electric All Rights Reserved
5
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