Reliability in motion

1

Welcome !

AWWA Motor Fundamentals Class

2012

Reliability in motion ™

• 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

2

Today we will cover:

1.

Motor styles

2.

How motors work

3.

Motor terminology

4.

Motor failure

5.

Energy savings

6.

Motor – ASD considerations

7.

Open questions


3


Toshiba International Headquarters – Houston, TX


Overview – TIC, Houston, Texas

• Established 1970

• Head Office/Factory located in Houston, TX.

• Annual Sales: ~ US$ 500 Million

• ~ 1,000,000 ft 2 on 50 acres

• ~ 1100 Employees

• 3 Manufacturing Plants: Motors, Power Electronics, and Controls

• Motor/ASD Test Lab (7 Dynamometers)

• ISO-9001 Certification (Plant wide)

4 / Copyright © 2006 by Toshiba International Corporation

5

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”


6

Styles of Motors


7


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

8

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

Parts of a Motor

Cooling Fan

Rotor/Stator Air Gap

Stator Laminations

Stator Windings

Rotor

Bearing

Drive Shaft

9

Terminal Box


10

Motor Rotor and Stator

• Note the rotor looks like a “squirrel cage”.


Moving field in stator pulls rotor


Figure 9 - The rotating magnetic field of an

AC motor.

11

12


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.

13


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

300

250

200

150

100

50

0

Design A or B

Design C

Design D

% of Synchronous Speed

14


Motor Terms Continued

• 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.

15


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

• Per cent power factor is a measure of a particular motor’s requirements for magnetizing amperage.

16


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.

17

NEMA frame dimension measurements ensure interchangeability.


18


Basic Motor Design

A Discussion on Torque


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:

Or:

HP = Speed in RPM x 2 P x torque

33,000

HP = torque (lb-ft) X RPM

5250

And:

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

19

1 pound

Torque and Foot-Pounds

1 foot

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.

20

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


21


22


Motor Torque Designs

• 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


• suited for a broad variety of applications, normal starting torque - common in

HVAC application with fans, blowers and pumps

23


Design Torque continued

• NEMA design C

• maximum 5% slip


• high locked rotor torque


• suited for equipment with high inertia starts - as positive displacement pumps

• NEMA design D

• maximum 5-13% slip


• very high locked rotor torque

• suited for equipment with very high inertia starts - as cranes, hoists etc.

24


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

25



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

26


Electric motor will continue to produce

Horsepower = Torque X RPM

5252

Until ---


27



• It Stalls “Breakdown Torque” or - preferably

• Motor overload relay trips or

• Burns out (Exceeding temperature/time capability of insulation) or

• Exceeds mechanical strength of bearings, shaft, or frame.

28

Speed-torque Curves:

300

250

200

150

100

50

0

% of Synchronous Speed

Design A or B

Design C

Design D


29

Choosing the right motor:

NEMA Design:

Starting current:

Starting torque:

Maximum torque:

A

High

Medium

High

B

Medium

Medium

Medium

C

Medium

High

Medium

D

Medium

Very high

Very high

APPLICATIONS

Design A and B: Fans, blowers, centrifugal pumps, unloaded compressors, and loads with low inertia.

Design C:

Design D:

High inertia loads such as large centrifugal blowers, fly wheels, and pulverizers. Also loads requiring high starting torques such as conveyors and loaded compressors.

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.


30


Advantages of higher Torque

• Prevents stalling in tough applications

• Ability to accelerate high inertia loads

• Startup and operating capabilities during brownouts

• Reduced voltage starting


31


Choosing the right motor

Some points to consider when specifying a new motor:

•Horsepower

•Speed (poles)

•Voltage

•Efficiency

•Torque (design letter)

•Dimensional constraints (frame size)

•Unusual service conditions

•Enclosure

•Coupling vs. Pulley drive

32

Motor Nameplate


33


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)

TENV (Totally Enclosed Non-Ventilated)

• TEBC (Totally Enclosed Blower Cooled) – This is usually a Vector Duty / ASD motor with a CT Speed Range of 120:1 or 1000:1.

•

Wash Duty / Stainless Steel

• Brake Motor 841 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, winding RTDs, Thermostats (klixons), F2 mounting, etc.)__________________________________________________________________



For Low Voltage Motors

34

• 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.

35

Open Drip Proof Motor


36

TEFC Enclosure


37


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

38


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

39 n n

What Causes of Motor Failure?

Insulation.......…20%

Bearings.........…80%


40


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

41


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

42


Causes of Motor Failure

n

Insulation

u u u u u u u u u u u

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

43


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.

44


Causes of Motor Failure

n

Bearings

u u u u u u u u u u u

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.

46


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)


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

47 /


20 Year Life Cycle Cost

Power Costs

Downtime

Costs

Rebuild Costs

5%

4%

Initial Costs 1%

0% 20% 40% 60%

(Total Life Cycle Costs as Percentage of

Net Present Value)

90%

80% 100%

48 /

Motor Construction

Each Motor is 10 HP, 1200 RPM

Standard efficiency

84%


49 /

Epact efficiency

87.5%

Premium

Efficiency 90.2%


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.

50 /


Global Consumption

51

Global electricity consumption (15.7 PWh/a)

• Pumps

• Fans

• Compressors for Cooling/Compressed Air

• Industrial Handling & Processing

• Transport

Motors

46%

Standby

3%

Source: Paul Waide/Conrad U. Brunner 2010

Light

19%

Heat

19%

Electronics

10%

Electrolysis

3%


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

52 /


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.

53 /

54

Motor Energy Savings Opportunities

Percentage of Total Motor System Energy

Specialized Systems

Compressed Air Systems

Fan Systems

Pump System

Rewind practices

Motor upgrade

2

0.8

0

5.5

17.1

20.1

3.5

5 10 15 20

Percentage of Total Motor System Energy

25


Confidential

55

Variable Frequency Drives

Variable Speed Drives

Adjustable Speed Drives

Adjustable Frequency Drives

AC Inverter

AC Drive


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.

57

Drives - A Historical Summary

Year

1930-1965

1965

Technologies

Mechanical, hydraulic, eddy current, and rotating DC drives

Solid state DC drives

1972 Current Source Inverter

Uses/Benefits

- First shaft speed control

- Simplicity

- Adjustability

- Reduced set-up

- Improved speed control mid '70s mid '80s early '90s

Variable Voltage Inverter

AC PWM (GTO inverters)

AC PWM (IGBT inverters)

- Use with AC motors

- Improved speed control

- Reduced noice, size

- Improved efficiency



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

AC Motor

Mechanical Variable Speed Drive

Variable speed shaft

Variable pitch diameters


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

60


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.

61


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.

62


100

80

60

40

20

75% FLOW

FLOW

REST

RICT

ED

FLO

W CO

NTR

OLL

ED

BY

ASD

900 1800 2700

MOTOR RPM/FLOW RATE

40% ENERGY SAVINGS

WHEN DRIVE IS USED IN

AN APPLICATION WHERE

FLOW IS RESTRICED BY

25% AVERAGE

3600

63


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.

64


ASD – Motor Considerations

• When using an adjustable speed drive to control a motor there are additional considerations:

1.

Motor speed range.

2.

Motor cooling.

3.

Load torque requirements

4.

Motor bearing protection - Fluting

5.

Motor lead length


Motor Drive

DIODE

RECTIFIER

DC BUS

CAPACITOR

V

LL-rms

I

3 frms

1 3 5

4 6 2

C

Natural Commutation

INVERTER

PWM Modulation

Voltage

-400

0

65

Current

/

-150

0.08

Input


Output

Motor

(2-20kHz)

Motor Drive with long leads

• Voltage Spikes can damage Motor & Cable insulation

• Drive’s voltage pulses are V dc



• Thousands of spikes per second

2 V

L

-

L


Drive’s Voltage Motor’s Voltage

66 / Copyright © 2007 Toshiba International Corporation. All rights reserved.

67


Example of PWM voltage damage to motor wiring

What A Failure Might Look Like

68

Example of Bearing Damage due to

ASD PWM Output Fluting


69


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.

Reliability in motion

Welcome !

Basic Motor Design

A Discussion on Torque

Until ---

Speed-torque Curves:

Choosing the right motor:

Choosing the right motor

Motor Nameplate

What Causes of Motor Failure?

Insulation.......…20%

Bearings.........…80%

Insulation Life

Causes of Motor Failure

Insulation

Causes of Motor Failure

Bearings

Do you know how much Electric

Motors Cost You?

Do you know how much Electric Motors cost you?

Cost New Cost to Operate

20 Year Life Cycle Cost

Standard efficiency

84%

Epact efficiency

87.5%

Premium

Efficiency 90.2%

Why is Improving Motor Efficiency Important?

Global Consumption

When should you consider buying a new Premium

Motor?

Should I rewind a failed Motor?

Variable Frequency Drives

Variable Speed Drives

Adjustable Speed Drives

Adjustable Frequency Drives

AC Inverter

AC Drive

Why use Variable Frequency Drives ?

Laws of Affinity

Energy Savings

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