Curso AC Full Magnetic.ppt

7/28/2019 Curso AC Full Magnetic.ppt

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A.C. Full MagneticCourse #806

Morris Material

Handling


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Safety

Objectives

At the Completion of thissection, the student should

know and understand the

standard safety precautions

as they apply to cranes andtheir operation.

References:

OSHA 1910.179 Shutdownconditions

ANSI/ASME B30


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Safety

Safety Precautions

Tags

Shutdown Conditions


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Safety

References:

OSHA 1910.179 Shutdownconditions

ANSI/ASME B30


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General Crane

Safety

Inform the operator or

person responsible forthe crane and all affected

employees that the crane

will be serviced.

Observe lock out and tag

out procedures. Always

verify the removal of

power.

Use platforms step and

ladders whenever

available.


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General Crane

Safety

Use a Safety harness not a

beltand remember tosecure it to a proper

location.

Always use P.P.E.

Insure that loose parts andtools dont fall.

Be aware of loose or torn

clothing that may get caught

in moving parts.


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General Crane

Safety

Select the appropriate tools

and test equipment for thejob.

Replace all guard and safety

devices being removed for

service before returning tonormal operation.


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General Crane

Safety

Upon completion of service,

inform the operator or theperson responsible for the

crane that service has been

completed .

Your plant may haveadditional requirements


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TAGS

Temporary means of

warning to all. Essential to safety and

health.

Not the only method of

warning to be employed.

Tags can only be removed

by the installing person.


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Shutdown

Conditions

Faulty or worn brakes

Structural problems

Worn or damaged wire

rope

Worn or damaged pawlsor ratchets

Worn or faulty hydraulics

Faulty switches


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Shutdown

Conditions

Faulty or missing fire

protection Malfunctioning operator

controls

Faulty, damaged or wornblocks and hooks

Faulty or missing

warning devices Faulty safety devices


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Basic Electronics

Review

Basic Circuit Review:

Definition of electrical terms

Ohms Law

Series and Parallel Circuits

Transformers Common Symbols


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Basic Electronics

Review

Diodes:

Operation

Half Wave Rectification

Full Wave Rectification

Diode Testing


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Basic Electronics

Review

Protective Devices:

Fuses

Thermal Overloads

Surge Suppressors

Circuit Breakers Pressure Switches

Timers

Limit Switches


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Basic Electronics

Review

Objective:

Upon Completion of thissection the participant

should have a basic

understanding of:

Ohms Law and how to apply itto circuits

Understand basic series and

parallel circuits

The operation and applicationof diodes

Understand the application of

protective devices


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Basic Electronics

Review

Protective Devices:

Fuses

Thermal Overloads

Surge Suppressors

Circuit Breakers Pressure Switches

Timers

Limit Switches


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Basic Electronics

Review

Voltage:


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Basic Electronics

Review

Current:


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Basic Electronics

Review

Power:


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Basic Electronics

Review

Ampere:


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Basic Electronics

Review

Watt:


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Basic Electronics

Review

Inductance:


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Basic Electronics

Review

Inductive Reactance:


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Basic Electronics

Review

Capacitance:


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Basic Electronics

Review

Capacitive Reactance:


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Basic Electronics

Review

The basic formula for Ohms

Law is as follows:

E = I x R

I =E/R

R =

E/I


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Basic Electronics

ReviewSeries Circuits:

The total Resistance of a

series circuit can bedetermined by using

following formula:

RT= R1 + R2+ R3 + R4+ etc.

The total voltage in a seriescircuit is equal to the sum of

the individual voltage drops.

ES= ER1 + ER2 + ER3 + ER4 +

etc.


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Basic Circuit Review

Parallel Circuits

The total resistance of a

parallel circuit can be

determined by using thefollowing formula:

_______________1_________

______

1/R1 + 1/R2 + 1/R3 +1/R4 +1/etc

The total voltage in a parallel

circuit is common in all

branches.

Es = E1 = E2 = E3 = E4 = etc.


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Diode

sOperati

on

Cathode -

Anode +


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Diod

es

Cathode is biased negative

with respect to the anode (andvice versa) in order for forward

bias to exist.

Electron flow (current) from

cathode to anode.


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Half-Wave

Rectification+

-

-

+

No current flow


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Bridge Rectifier with

Filter


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Diode Testing

These tests only determine if a

diode is open or shorted. Theydo not indicate or detect

leakage current or a weak

diode. Other testing devices

are available that do test alloperations of diodes.


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3-phase AC Motors

Section Outline

Construction

Overall Motor

Rotors

Duty & Temperature Rating

Speed & Torque Curves


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3-phase AC Motors

Motor Operation

Rotating Stator Fields Rotor Currents & Torque

Motor Problems &

Symptoms Stator Single Phased

Rotor Single Phased

Improper Connections

Unbalanced Resistance


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3-phase AC Motors

Motor Testing

Current Tests Voltage Tests

Grounding Tests

Periodic Maintenance Brushes & Slip Rings

Lubrication

Cleaning


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Motor Construction

1. Stator Housing 4. Bearing

2. Stator Coil 5. End Cap

3. Rotor


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Motor Construction


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Motor Duty and

Temperature Ratings

X

X

X


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Motor Operation

T1 T2 T3

S

NSN

s

n

s

n

s

n

s

n

-10

+5

+5


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Motor Operation

T1 T2 T3

n

sn s

N

S

N

S

s

n

s

n

+5

-10

+5


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Motor Operation

S

N S

N

N

S

S

N

S

N

S

N


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Rotor Currents and

Torque

Rotating stator fields induce

currents in rotor bars. Rotor Currents produce

magnetic poles that chase the

stators magnetic poles.


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Problems &

Symptoms

Symptom: Motor growls,cantachieve full speed, poor torque,

sluggish operation, heat may trip

overloads, sounds like a noisy

gearbox.


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Problems &

Symptoms

Symptom: Cant pick up a full

load, primary amps too high,

voltages and currents unbalanced,

trips overloads or smokes themotor.


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Motor Testing:Current Test

Remove brake fuses or gently

run the crane against the endstop.

Place the controller in first

point.

Using a clamp-on ammeter,read the current on the three

input Tleads, they must be

within 2% of each other.

Using a clamp-on ammeter,

read the current on the three

rotor Mleads, they must be

within 2% of each other.


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Motor Testing:Voltage Test

Open the rotor circuit.

Read the input phase to phaseand the rotor lead to lead. The

reading must be balanced and

agree with the nameplate

voltage.


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Motor Testing:Resistance Test

Open the input leads to the

stator. Open the rotor leads.

Using a multi-meter set to the

appropriate scale read the

primary stator winding

phase to phase. The resistance

should be low, but not zero.

Then read the secondaryrotor winding phase to phase.

The resistance should be low,

but not zero.


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Motor Testing:Resistance Test

Next read each winding to

ground using a meggar. Theresistance should at least 1

megohm to ground.


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er o cMaintenance: TypicalBrush Assemblies


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Speed Control

Introduction

Objectives

Upon completion of this section,the participant should be familiar

with and:

Be able to recognize festoon and

collector bar type power transfer

systems.

Understand basic power distribution

schematics.

Develop a basic understanding of

various motor controls and how they

work together as a system


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Power Distribution

Festoon System


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Speed Control

Techniques

Change Synchronous Speed

Change the number of statorpoles.

Change the frequency of the

applied power.

Change Motor Slip Vary the primary voltage

Vary the secondary resistance

Vary the secondary reactance


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Speed Control

Single Speed


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Speed Control

Reduced Torque Starting

100%

100%

75%

75%

Voltage builds slowly through anautotransformer


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Speed Control

Reduced Torque Starting

Gate Pulse

Start

Gate Pulse

Advance


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Speed Control

Two Speed


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Speed Control

Multi-speed Magnetic


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Speed Control

Multi-speed Magnetic


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Speed Control

Saturable Reactor

Induction

Master

More DC Current Less

impedence less slip

more speed

Master

Bias


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Speed Control

Adjustable Frequency


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Speed & Load

Curves


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Speed & Load

Curves


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Protection Circuits

Over Current Protection:

Thermal and Magnetic overloadsand fuses

Power and Control Circuits

Over Heating Protection:

Thermal switches and pluggingcircuits

Motor and solid state electrical

components


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Protection Circuits

Travel Limits:

Hoist Motions - geared andweight operated limits for power

and control sections

Traverse Motions - lever and

magnetic operated circuits Operational Safety Circuits:

Schematic Representations:

Device Maintenance &

Adjustment:


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Protection Circuits

Objectives

Upon completion of this sectionthe participant should:

Understand the basic concept

behind protection circuits.

Be familiar with the different types of

limit switches. Understand that a limit switches is a

SAFETY device and is not to be used

as a control device.

Become familiar with the operation

of bi - metallic, dashpot and meltingalloy overloads.


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Protection Circuits

Klixon

Thermal OL


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Protection Circuits

Magnetic OL

Neutral Safety SW.


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Limit Switches

Weight Operated


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Limit Switches

Weight Operated


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Limit Switches

Weight Operated


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Limit Switches

Gear Operated


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Overloads

Oil Filled Dashpots

Change Oil Annually

2/3 full, must be

ranslucent

Hand tighten only


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Overloads

Oil Filled Dashpots


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Overloads

Melting Alloy Type

Lead = 450 F

Tin = 680 F

60/40 Mix = 370


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Overloads

Melting Alloy Type


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Overloads

Bi - Metallic


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Brakes

Holding Brakes:

Release Time Comparison AC Brakes

DC Brakes

Typical Brake Rectifier Circuits

Electric Load Brakes: Capacitive Dynamic Braking

Eddy Current Brakes


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Brakes

Objectives:

This section promotes anunderstanding of the operation

and maintenance of brakes and

their control circuits.


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Brake Release Time

X

X


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AC Motor Brakes


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AC Solenoid Brake


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DC Disc Brake


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DC Shoe Brake (CD)


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DC Shoe Brake

(SBE)


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DC Disc Brake

Rectifier


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DC Shoe Brake

Rectifier

Economizer


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DC Shoe Brake

Rectifier

Economizer


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DC Shoe Brake

Rectifier

Economizer


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Capacitive Dynamic

Braking

Rotor induces back into

capacitor if brake fails.As rotor voltage drops,

capacitor sees drop

and discharges into

stator.


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Capacitive Dynamic

Braking


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Capacitive Dynamic

Braking


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Magnetorque


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Magnetorque


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Multi-Speed

Magnetic Control

Basic Principles:

Secondary Resistors: Construction & Maintenance

Classification

Timed Acceleration Control:

Voltage Acceleration Control:

Typical Accelerating Relays:


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Motor Secondary

Circuit


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Motor Secondary

Circuit


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Secondary Resistors


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Power On


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Power O


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Typical Accelerating

Relays


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Saturable Reactor

Control

Basic Principles:

Block Diagrams: Basic Magnetics:

Saturable Reactors:

Construction & Maintenance

Operation

Magnetic Amplifiers:

Construction

Operation DC Power Supplies:

Silicon Controlled Rectifiers

Typical DC Power Supply


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Motor Secondary


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Control Block

Diagram

w/o Magnetorque


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V


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Magnetic Fields

Basic Magnetics

3A


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Magnetic Fields

Basic Magnetics

1.5A2A


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Magnetic Amplifier

2A 3A 2A


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Saturable Reactors

+ -

+


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Saturable Reactors

+ -

-

+


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Saturable Reactors


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Magnetic Amplifier

Control Windings

Master

Bias

Frequency

When core saturates, current flows

in output xfmr to generate gatepulses

AC IN Gate Pulse


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Magnetic Amplifier

Module - MFA

The Magnetic Amplifier is a

self - saturating device. Thereare up to six control signals in

the control windings that

influence the saturation of

cores.


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Frequency

Bias

Master

Anti-Hunt

Plugging

OPB


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Magnetic Firing Amp

Module Schematic


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Freq.

BIAS

Master

Anti-Hunt

Plugging

OPB


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Silicon Controlled

Rectifiers


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Silicon Controlled

Rectifiers

+ Anode - Cathode

+ Gate

Anode

Cathode

Gate


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Silicon Controlled

Rectifiers

Rules of Conduction

The SCR must be forward biased.The anode is positive with

respect to the cathode.

The SCR must receive a positive

gate pulse while forward biased.

The SCR must reach a minimum

holding current to break down

the junction.

Once conduction begins, the

SCR will not turn off until thejunction is reversed biased or the

current drops below the

minimum holding value.


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Typical DC Power

Supply

A. Fuse

B. Bridge Rectifier

C. Amp Meter

D. Current Limiting Resistance

E. Reactors

F. Magnetorque

G. Anode Transformer


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Typical DC Power

Supply

Allows fiield built bycoils to dissipate


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Typical DC Power

Supply


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Control Block

Diagram

w/ Magnetorque


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Adjustable

Frequency Control

Control Fundamentals:

Motor Speed Reactance & Stator Current

Inductance & Torque

V/F Patterns

Pulse Width Modulation 3-Phase PWM Waveforms

Block Diagram:

3-Phase AC-DC Converter:

3-Phase DC-AC Inverter:

Regeneration & Dynamic

Braking:


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AF Control

Fundamentals

Motor Speed

Ns=120 x Frequency

# of Poles

Reactance & Stator Current

XL= 2FL

IS =_V_ = _V__

XL 2FL


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AF Control

Fundamentals

Induction & Torque

e = B l v

T = B l i


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AF Control

Fundamentals

V/F Patterns


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AF Control

Fundamentals

V/F Patterns

9


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AF Control

Fundamentals

Pulse Width Modulation

D

C

B

U

S

Time Cycle


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3-Phase PWM

Waveform

120 phase to phase electronically produced

electronically reversed


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AF Block Diagram

Spine

Brain

Customize con

Parameters


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3-Phase AC-DC

Converter


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3-Phase AC-DC

Converter

Single Phase to charge

slowly


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3-Phase DC-AC

Inverter


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3-Phase DC-AC

Inverter Freewheeling diodes


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Regeneration


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Dynamic Braking


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Dynamic Braking

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