Download Reliability in motion

Reliability in motion ™
Welcome !
AWWA Motor Fundamentals Class
2012
• Presenter: Rick Fink of Toshiba International Corporation
• 6 Years with Toshiba – Motors, Drives and Motors Controllers
• 24 Years Electrical Power distribution, Motor Controls and
Automation
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Reliability in motion ™
Today we will cover:
2
1.
Motor styles
2.
How motors work
3.
Motor terminology
4.
Motor failure
5.
Energy savings
6.
Motor – ASD considerations
7.
Open questions
Reliability in motion ™
Toshiba International Headquarters – Houston, TX
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Reliability in motion ™
Overview – TIC, Houston, Texas
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Established 1970
Head Office/Factory located in Houston, TX.
Annual Sales: ~ US$ 500 Million
~ 1,000,000 ft2 on 50 acres
~ 1100 Employees
3 Manufacturing Plants: Motors, Power Electronics,
and Controls
Motor/ASD Test Lab (7 Dynamometers)
ISO-9001 Certification (Plant wide)
/
Copyright © 2006 by Toshiba International Corporation
Reliability in motion ™
Motors – Styles
Low Voltage Motors:
• 115v – 230v1phase, 230v – 460v – 575v 3 phase
• Fractional to 1200hp. Most are < 400hp
• General Purpose TEFC, ODP
• 56 C Face
• Inverter Duty Motors
• Submersible
• NEMA Design C Motors
• Explosion Proof Motors (VFD Rated)
• Stainless Steel “Food Grade Motors”
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Reliability in motion ™
Styles of Motors
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Styles and Horsepower
Medium Voltage Motors:
• Medium Voltage Motors
(To 50,000Hp 15KV)
• ODP, WP I, WP II, TEFC, TEAAC, TEWAC, TEFV and Vertical
Pump (500Hp and UP)
• 2300, 4160, 6600, 15KV
• Up to 4000Hp 2300, 4160V Manufactured in Houston,TX
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Reliability in motion ™
How Does a Motor Work?




Convert electrical energy into
mechanical energy.
1831 - Faraday invented the
magneto
1888 - Nikola Tesla invented the
induction motor.
1896 - General Electric produced
the first commercial induction motor.
Nikola Tesla
1856 - 1943
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Reliability in motion ™
Parts of a Motor
Rotor/Stator Air Gap
Stator Laminations
Cooling Fan
Stator Windings
Rotor
Drive Shaft
Terminal Box
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Bearing
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Motor Rotor and Stator
• Note the rotor looks like a “squirrel cage”.
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Moving field in stator pulls rotor
Figure 9 - The rotating magnetic field of an
AC motor.
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GLOSSARY OF FREQUENTLY OCCURRING MOTOR
TERMS
• FLA - Full Load Amps
• The amount of current the motor can be expected to draw under
full load (torque)
• Also know as nameplate amps.
• LRA - locked rotor amps
• Also known as starting inrush, this is the amount of current the
motor can be expected to draw under starting conditions when full
voltage is applied.
• Service Factor - Motor load and current rating when loaded to the
service factor on the nameplate of the motor. Base is 1.0 but for
example, many motors will have a service factor of 1.15, meaning
that the motor can handle a 15% overload. The service factor
amperage is the amount of current that the motor that the motor
will draw under the service factor load condition.
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Reliability in motion ™
Motor Terms
• RPM is the rotational speed of the motor under full load conditions.
It will always be less than the synchronous speed Ex 1800 rpm 4
pole motor will operate in the 1755 to 1765 rpm range.
• Design – Torque profile
% of Full Load Torque
300
250
200
Design A or B
150
Design C
100
Design D
50
% of Synchronous Speed
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100
90
80
70
60
50
40
30
20
10
0
0
Reliability in motion ™
Motor Terms Continued
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•
PHASE
•
Phase is the indication of the type of power supply for which the motor is designed Two
major categories exist; single phase and three phase.
•
POLES
•
This is the number of magnetic poles that appear within the motor when power is applied.
Poles always come in sets of two (a north and a south). Thus, the number of poles within a
motor is always an even number such as 2, 4, 6, 8, 10, etc.
•
In an AC motor, the number of poles work in conjunction with the frequency to determine
the synchronous speed of the motor.
Reliability in motion ™
Motor Terms Continued
At 50 and 60 cycles, the common arrangements are:
Poles - Synchronous Speed
•
60 Cycles 50 Cycles
•
2 - 3600
3000
•
4 - 1800
1500
•
6 - 1200
1000
•
8 - 900
750
•
10 - 720
600
POWER FACTOR
•
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Per cent power factor is a measure of a particular motor’s requirements for
magnetizing amperage.
Reliability in motion ™
Frame Designations & Descriptions
• NEMA (National Electrical Manufacturer’s Association)
• National Electrical Manufacturers Association is a trade
association. There are 17 member firms in the Motor and
Generator Section.
• NEMA Standards Publication No. MG 1 - 1998 MOTORS AND
GENERATORS is the most widely cited standard for motors in
the U.S., it has a 5-year revision cycle.
• NEMA Defines critical dimensions: mounting holes shaft
height, and diameter, as well as shaft length.
• NEMA has set up frame designations relative to Horsepower
Rating and Rpm. Example: a 1hp 1800rpm is in a NEMA 143T
Frame and a 100hp 1800rpm motor is in a 404T or TS frame.
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NEMA frame dimension measurements ensure
interchangeability.
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Basic Motor Design
A Discussion on Torque
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Torque and HP.
Torque is turning effect. Horsepower is the
rate of doing work.
• Torque is described in foot-pounds
• By definition, one horsepower equals 33,000 footpounds per minute
Consider:
HP = Speed in RPM x 2P x torque
33,000
1 pound
Or:
Torque and Foot-Pounds
HP = torque (lb-ft) X RPM
5250
And:
1 foot
Torque (lb-ft) = HP x 5250
RPM
This involves torque at a steady speed. Since additional
torque is necessary to overcome the inertia of starting,
starting torque will be higher than rated load torque
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The force of one pound is needed to turn the wheel
at a steady rate. Therefore, the torque is one pound
times one foot or one foot-pound.
Reliability in motion ™
Basic Motor Design
Torque – Twisting (rotational) Force
A Motor is a Time – Rated, Torque Device
Torque Components:
Locked Rotor (Pull in) Torques
Pull Up Torques
Breakdown Torques
Locked Rotor Amps
WK2 Capabilities
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Reliability in motion ™
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Motor Torque Designs
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•
NEMA design A
•
maximum 5% slip
•
high to medium starting current
•
normal locked rotor torque
•
normal breakdown torque
•
suited for a broad variety of applications - as fans and pumps
•
NEMA design B
•
maximum 5% slip
•
low starting current
•
high locked rotor torque
•
normal breakdown torque
•
suited for a broad variety of applications, normal starting torque - common in
HVAC application with fans, blowers and pumps
Reliability in motion ™
Design Torque continued
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•
NEMA design C
•
maximum 5% slip
•
low starting current
•
high locked rotor torque
•
normal breakdown torque
•
suited for equipment with high inertia starts - as positive displacement pumps
•
NEMA design D
•
maximum 5-13% slip
•
low starting current
•
very high locked rotor torque
•
suited for equipment with very high inertia starts - as cranes, hoists etc.
Reliability in motion ™
Torque / Inertia Capabilities
The Horsepower listed on the nameplate of a motor is a statement of the
Torque it will produce at a set RPM for defined period of time
Horsepower = Torque X RPM
5252
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Reliability in motion ™
Torque / Inertia Capabilities
A 10HP 1800 rpm TEFC NEMA B Electric Motor will develop
30 ft-lbs. of torque at 1800 rpm continuously and meet
certain minimum performance criteria as defined by
NEMA
30 ft-lbs Torque = 10Hp X 5252
1800 RPM
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Torque / Inertia Capabilities
Electric motor will continue to produce
Horsepower = Torque X RPM
5252
Until ---
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Reliability in motion ™
Torque / Inertia Capabilities
•
It Stalls “Breakdown Torque”
or - preferably
•
Motor overload relay trips
or
•
Burns out (Exceeding temperature/time capability of insulation)
or
•
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Exceeds mechanical strength of bearings, shaft, or frame.
Reliability in motion ™
Speed-torque Curves:
% of Full Load Torque
300
250
200
Design A or B
150
Design C
100
Design D
50
% of Synchronous Speed
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100
90
80
70
60
50
40
30
20
10
0
0
Reliability in motion ™
Choosing the right motor:
NEMA Design:
A
B
C
D
Starting current:
High
Medium
Medium
Medium
Starting torque:
Medium
Medium
High
Very high
High
Medium
Medium
Very high
Maximum torque:
APPLICATIONS
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Design A and B:
Fans, blowers, centrifugal pumps, unloaded compressors,
and loads with low inertia.
Design C:
High inertia loads such as large centrifugal blowers,
fly wheels, and pulverizers. Also loads requiring high
starting torques such as conveyors and loaded compressors.
Design D:
Very high inertia loads and loads which require very high
starting torques. Loads which require large speed
variations such as punch presses; also hoists and elevators.
Reliability in motion ™
Torque / Inertia Capabilities
Advantages of higher Torque
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•
Prevents stalling in tough applications
•
Ability to accelerate high inertia loads
•
Startup and operating capabilities during brownouts
•
Reduced voltage starting
Reliability in motion ™
Choosing the right motor
Some points to consider when specifying a new motor:
•Horsepower
•Speed (poles)
•Voltage
•Efficiency
•Torque (design letter)
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•Dimensional constraints (frame
size)
•Unusual service conditions
•Enclosure
•Coupling vs. Pulley drive
Reliability in motion ™
Motor Nameplate
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Reliability in motion ™
Motor Request Worksheet
•
NAMEPLATE DATA:
•
HP _____ RPM_____ Voltage_______ HZ____ Phase_____ FLA _____ Frame _________
•
Enclosure: ______________________ {Write it down or Circle the enclosure}
•
TEFC (Totally Enclosed Fan Cooled)
•
ODP (Open Drip Proof)
•
TEBC
•
Wash Duty / Stainless Steel
•
Brake Motor
•
Exp. Proof – Division_____ Class_____ Group_____
•
Options / Modifications: (Write down if they have modifications. Modifications / options could be: using a tach or encoder, bearing RTDs,
TENV (Totally Enclosed Non-Ventilated)
(Totally Enclosed Blower Cooled) – This is usually a Vector Duty / ASD motor with a CT Speed Range of 120:1 or 1000:1.
841 motor
winding RTDs, Thermostats (klixons), F2 mounting, etc.)__________________________________________________________________
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Reliability in motion ™
Frame Designations & Descriptions
For Low Voltage Motors
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•
ODP – Open Drip Proof – No direct protection for the windings or the bearings.
Air is enters through the lower ports and exhausted through the top vents.
Ventilation openings prevent liquids or solids from entering the motor at any
angle less than 15 degrees from the vertical.
•
TEFC – Totally Enclosed Fan Cooled – Motor is Totally Enclosed and is cooled
with a Fan blowing over the frame of the motor. Internal air is being circulated
by internal fins on the rotor that act as a fan. Can be used in dirty, moist, or
mildly corrosive operating conditions.
•
TENV – Totally Enclosed Non Vented - The motors body is being used as a
heat sink to dissipate the heat buildup. Normally seen in small horsepower
motors.
•
TEAO – Totally Enclosed Air Over – Designed as a TENV but must be mounted
within an air stream to properly dissipate heat.
Reliability in motion ™
Open Drip Proof Motor
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Reliability in motion ™
TEFC Enclosure
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Reliability in motion ™
Frame Designations & Descriptions
For Low Voltage Motors
• TEXP – Totally Enclosed Explosion Proof – Motor carries a U.L.
Label for Class 1 Division 1 Group D and Class 1 Div 2 Groups
E,F, and G. Used primarily in Explosion Proof applications.
• Severe Duty – No NEMA Designation
• Mill and Chemical Duty - Not a NEMA Designation
• IEEE 841 – Institute of Electrical and Electronics Engineers
NEMA Designations end at 200Hp
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Reliability in motion ™
Terminal Box Designations
for Low Voltage Motors
• F1 – Standard configuration – When looking at the motor from the
Fan End, (ODP) the Terminal Box (T-Box) will be on the RIGHT
side of the motor.
• F2 – When looking at the motor from the Fan End, (ODP) the
Terminal Box (T-Box) will be on the LEFT side of the motor.
• This is true for all motor manufacturers
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Reliability in motion ™
What Causes of Motor Failure?
n
n
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Insulation.......…20%
Bearings.........…80%
Reliability in motion ™
Motor Cooling
Choosing the correct motor for the application is by far the best
ways to keep it cool. Heat will destroy a motor
► The life of the insulation is reduced in half for each 10°C increase in
temperature.
► Insulation life, when operated at its rating, is 20,000 hours, with 90%
reliability. “Average life” is 100,000 hours on sinusoidal power.
► Heat reduces insulation life even more when the motor is operated on
VFD power supply.
► Lubrication life is cut in half for every 15 degrees Celsius rise
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Reliability in motion ™
Insulation Life
Insulation Design / Temperature Rise
The life of a class of insulation at rated temperature is 40,000
hours (4.55 years)
A class F insulation system with a B rise will have an expected
life of 200,000 hrs (22.8 years) when operated at nameplate
horsepower and speed
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Reliability in motion ™
Causes of Motor Failure
n
Insulation
u
u
u
u
u
u
u
u
u
u
u
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Voltage spikes
Excessive Number of Starts
Contaminants
Excessive Load Inertia
Singe Phasing
Locked Rotor
Overload – Motor controllers are designed to do this but..
High Ambient
Ventilation Failure
Thermal Aging
Vibration
Reliability in motion ™
NEMA INSULATION
TEMPERATURE RATINGS
Insulation systems are arranged in their order of insulation level and classified by
a letter symbol or numerical value:
► Class B / Class 130
130° C
266° F
► Class F / Class 155
155° C
311° F
► Class H / Class 180
180° C
356° F
The temperature classification indicates the maximum (hot spot) temperature at
which the insulation system can be operated for normal expected service life.
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Reliability in motion ™
Causes of Motor Failure
n
Bearings
u
u
u
u
u
u
u
u
u
u
u
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Over lubrication
Under Lubrication
Grease – Limited by Temperature, Time and Contaminants
Thrust
Side Loading
Vibration
Bearing Currents
High Ambient
Fatigue....L10
Undersized Bearings
Improperly designed Shaft Support System
Confidential
Do you know how much Electric
Motors Cost You?
Copyright © 2005 Toshiba International Corporation. All rights reserved.
Reliability in motion ™
Efficiency values for industrial motors - NEMA PREMIUM™
• Table 12-11 (in NEMA MG 1-1998 Rev 2) shows “Full Load Efficiencies of
Energy Efficient Motors”, up to 500 HP.
• Those motors having nominal full-load efficiency greater than the values in
that table may be classified as “energy efficient.” (NEMA MG 1-1998 Rev
2, 12.59)
46
Reliability in motion ™
Do you know how much Electric Motors
cost you?
Cost New
Cost to Operate
• 100Hp
$4,146
$35,730
• 75Hp
$3,378
$27,092
• 50Hp
$1,860
$18,141
• 20Hp
$809
$7,445
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/
Reliability in motion ™
20 Year Life Cycle Cost
90%
Power Costs
Downtime
Costs
5%
Rebuild Costs
4%
Initial Costs
1%
0%
20%
40%
60%
(Total Life Cycle Costs as Percentage of
Net Present Value)
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/
80%
100%
Motor Construction
Each Motor is 10 HP, 1200 RPM
Reliability in motion ™
Standard
efficiency
84%
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/
Epact
efficiency
87.5%
Premium
Efficiency 90.2%
Reliability in motion ™
Why is Improving Motor Efficiency Important?
• Saving money
• The country will continue to electrify
• Over 50% of all Electrical Energy consumed in the USA is used
by Electric Motors. Do you know how many Motors you have in
your Home?
• 80% of the Electrical Energy consumed in US industry is used
by Electric Motors. Improving the efficiency of Electric Motors
and the equipment they drive can save energy and reduce
operating costs.
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/
Reliability in motion ™
Global Consumption
Global electricity consumption (15.7 PWh/a)
Light
19%
• Pumps
• Fans
• Compressors for Cooling/Compressed Air
Motors
46%
Electronics
10%
• Industrial Handling & Processing
Electrolysis
3%
• Transport
Standby
3%
Source: Paul Waide/Conrad U. Brunner 2010
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Heat
19%
Reliability in motion ™
When should you consider buying a new Premium
Motor?
New Premium Motors should be considered in the following cases:
• For all new installations
• Purchasing new equipment packages, Air Compressors, HVAC
Systems, and Pumps
• Major modifications made to facilities or processes
• Instead of rewinding older Motors
• Replace oversized and under loaded Motors
• Part of a Preventive Maintenance or Energy Conservation
Program
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/
Reliability in motion ™
Should I rewind a failed Motor?
Failed Motor usually can be rewound, it is often worthwhile to
replace a damaged motor with anew NEMA Premium Motor to
save energy and improve reliability.
• Motor is less than 75Hp.
• Cost to rewound exceeds 65% of the price of a new Motor.
• Motor was rewound before 1980.
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/
Reliability in motion ™
Motor Energy Savings Opportunities
Percentage of Total Motor System Energy
Specialized Systems
2
Compressed Air Systems
17.1
Fan Systems
5.5
Pump System
20.1
Rewind practices
0.8
Motor upgrade
3.5
0
5
10
15
20
Percentage of Total Motor System Energy
54
25
Confidential
Variable Frequency Drives
Variable Speed Drives
Adjustable Speed Drives
Adjustable Frequency Drives
AC Inverter
AC Drive
55
Copyright © 2005 Toshiba International Corporation. All rights reserved.
Confidential
• The electric AC Motor is over 100 Years old
• When voltage is applied to the motor it accelerates to full speed
as fast as it can both mechanically and electrically
• Throughout time people tried to find ways to slow down the
speed of the motor to be able to apply it to a wider range of
applications in manufacturing
• The first method was to increase the “poles” of the motor to reduce
speed; 2 Pole = 3600 Rpm, 4 Pole = 1800 Rpm,
6 Pole = 1200 Rpm, 8 Pole = 900 Rpm; etc.
56
Copyright © 2005 Toshiba International Corporation. All rights reserved.
Reliability in motion ™
Drives - A Historical Summary
Year
Technologies
Mechanical, hydraulic, eddy
1930-1965
current, and rotating DC drives
57
-
Uses/Benefits
First shaft speed control
Simplicity
Adjustability
Reduced set-up
1965
Solid state DC drives
1972
Current Source Inverter
- Improved speed control
mid '70s
Variable Voltage Inverter
- Use with AC motors
mid '80s
AC PWM (GTO inverters)
- Improved speed control
early '90s
AC PWM (IGBT inverters)
- Reduced noice, size
- Improved efficiency
Reliability in motion ™
The Mechanical Variable Speed
Drive.
Using mechanical means through the
use of belts, and varying the diameter
of pulleys, variable speed is possible.
• Features
• Mature Technology (been around
forever and still used today)
• Simple, easy to understand
• Relatively low cost
• Limitations
• Belt/sheave wear
• Special start-up/shutdown
procedures required for high inertia
loads
• High Maintenance
• Reduces bearing life in motors
58
Mechanical Variable Speed Drive
Variable speed shaft
AC Motor
Variable pitch diameters
Reliability in motion ™
Pulse Width Modulated Drive (PWM),
(AFD), (ASD)
A diode bridge creates a constant voltage DC,
which is chopped into adjustable output
frequencies which control motor speed.
• Features
• Uses standard induction motors (should have “Inverter
Rated” insulation system)
• Good efficiency at full speed, full load
• High displacement power factor
• Bypass capable
• Good with high inertia loads
• Easy installation
• No tach feedback required
• Remote control possible
• Drive can be tested unloaded
• More than one motor can be connected to one drive
• Open circuit protection
• Common bus regeneration
• Smooth low speed operation
• Closed & Open Loop Vector control performance (optional)
• Ride through options available
• Limitations
• Susceptibility to line transients
• Current harmonic distortion, dependant on line impedance
• High frequency content in PWM
• Initial cost is high
• Extra hardware for regeneration
• Motor noise
• Full power conversion required
• High service costs
59
Pulse Width Modulated AC Drive
Line
Converter
Inverter
Motor
Constant volt
DC bus
Reliability in motion ™
Why use Variable Frequency Drives ?
• Vary the speed of AC motor by controlling voltage and frequency.
• Increased process control over conventional valves and dampers.
• Inherent soft start feature reduces mechanical and electrical shock
to motor and driven mechanical equipment.
• Decrease or eliminate pump cavitation.
• Decrease maintenance costs.
• Increase mechanical efficiency by eliminating friction from valves
and dampers.
• AKA: Save money on the user’s power bill.
• Typical variable torque application can pay for additional cash
outlay within 12-18 months.
60
Reliability in motion ™
Laws of Affinity
• Centrifugal pump: Load varies as the square of the change in
speed.
• Centrifugal fan: Load varies as the cube of the change in speed.
• Energy savings predicated on these concepts.
61
Reliability in motion ™
75% FLOW
% POWER USAGE
100
80
60
ED
RICT
T
S
E
R
FLOW
40
20
W
FLO
LED
L
O
NTR
A
BY
SD
CO
900
1800
2700
MOTOR RPM/FLOW RATE
62
40% ENERGY SAVINGS
WHEN DRIVE IS USED IN
AN APPLICATION WHERE
FLOW IS RESTRICED BY
25% AVERAGE
3600
Reliability in motion ™
Energy Savings
• Most centrifugal devices designed for worst case operating
conditions.
• Typical fan and pump applications can operate at 30% below
design point, save $$ in the form of energy savings.
• If operating on co-gen power system,
ASD will increase amount of power available for resale back to
utility.
63
Reliability in motion ™
ASD – Motor Considerations
• When using an adjustable speed drive to control a motor there are
additional considerations:
64
1.
Motor speed range.
2.
Motor cooling.
3.
Load torque requirements
4.
Motor bearing protection - Fluting
5.
Motor lead length
Reliability in motion ™
Motor Drive
DIODE
RECTIFIER
I3f-rms
1
3
DC BUS
CAPACITOR
INVERTER
5
VLL-rms
Motor
C
4
6
2
PWM Modulation
Natural Commutation
(2-20kHz)
400
300
200
Voltage
Volts
100
0
-100
-200
-300
-400
0
0.005
0.01
0.015
Tiempo
0.02
0.025
0.03
150
100
Current
Amperes
50
0
-50
-100
-150
0.08
0.09
0.1
Input
65
/
Copyright © 2007 Toshiba International Corporation. All rights reserved.
0.11
0.12
Tiempo
0.13
Output
0.14
0.15
0.16
Reliability in motion ™
Motor Drive with long leads
• Voltage Spikes can damage Motor & Cable insulation
• Drive’s voltage pulses are
Vdc  2VL- L
• Thousands of spikes per second
Drive’s Voltage
66
/
Copyright © 2007 Toshiba International Corporation. All rights reserved.
Motor’s Voltage
Reliability in motion ™
Example of PWM voltage damage to motor wiring
What A Failure Might Look Like
67
Reliability in motion ™
Example of Bearing Damage due to
ASD PWM Output Fluting
68
Reliability in motion ™
Summary
• Choose the right size (power) motor.
• Pick motor features to match environment.
• Protect the motor.
• Energy efficient motors and their use with ASD’s can save money
and improve system performance.
69