motor_control_centers.pdf

Table of Contents

Introduction...............................................................................2

Motor.Control............................................................................4

Power.Supplies..........................................................................8

Design.Standards.................................................................... 2

Need.for.Circuit.Protection...................................................... 3

Overcurrent.Protection.Devices.............................................. 8

Motor.Control.Centers............................................................22

TIASTAR.MCC.Construction....................................................33

Combination.Motor.Control.Units...........................................44

Motor.Starters.........................................................................5

Pilot.Devices............................................................................57

Circuit.Breakers.......................................................................59

Other.Types.of.Devices.in.MCCs.............................................6

TIASTAR.Ordering.Information................................................64

Review.Answers.....................................................................66

Final.Exam...............................................................................67

quickSTEP.Online.Courses......................................................72

Introduction

Welcome.to.another.course.in.the.STEP.series,. S iemens.

T echnical. E ducation. P rogram,.designed.to.prepare.our.

distributors.to.sell.Siemens.Energy.&.Automation.products.

more.effectively..This.course.covers. Basics of Motor Control

Centers ..

Upon.completion.of. Basics of Motor Control Centers ,.you.

should.be.able.to:

•

Explain.the.role.of.motor.control.centers.in.a.distribution.

system

•

Define.a.motor.control.center.according.to.NEMA.and.UL

•

Explain.the.need.for.circuit.protection

•

Identify.various.components.of.a.motor.control.center

•

Explain.the.difference.between.the.various.classifications.

and.types.of.motor.control.center.wiring

•

Explain.features.of.the.TIASTAR.motor.control.centers

This.knowledge.will.help.you.better.understand.customer.

applications..In.addition,.you.will.be.better.prepared.to.describe.

motor.control.products.to.customers..You.should.complete.

Basics of Electricity and Basics of Control Components .

before.attempting. Basics of Motor Control Centers .

If.you.are.an.employee.of.a.Siemens.Energy.&.Automation.

authorized.distributor,.fill.out.the.final.exam.tear-out.card.and.

mail.in.the.card..We.will.mail.you.a.certificate.of.completion.if.

you.score.a.passing.grade..Good.luck.with.your.efforts.

Siemens.is.a.trademark.of.Siemens.AG..Product.names.

mentioned.may.be.trademarks.or.registered.trademarks.of.their.

respective.companies..Specifications.are.subject.to.change.

without.notice.

National.Electrical.Code®.and.NEC®.are.registered.trademarks.

of.the.National.Fire.Protection.Association,.Quincy,.MA.0269..

Portions.of.the.National.Electrical.Code.are.reprinted.with.

permission.from.NFPA.70-2008,.National.Electrical.Code®,.

MA.0269..This.reprinted.material.is.not.the.complete.and.

official.position.of.the.National.Fire.Protection.Association.on.

the.referenced.subject.which.is.represented.by.the.standard.in.

its.entirety.

NEMA®.is.a.registered.trademark.and.service.mark.of.the.

National.Electrical.Manufacturers.Association,.Rosslyn,.VA.

22209.

Underwriters.Laboratories.Inc..and.UL.are.registered.

trademarks.of.Underwriters.Laboratories.Inc.,.Northbrook,.IL.

60062-2096.

Other.trademarks.are.the.property.of.their.respective.owners.

Motor Control

Power.distribution.systems.used.in.large.commercial.and.

industrial.applications.can.be.complex..Power.may.be.

distributed.through.switchgear,.switchboards,.transformers,.

and.panelboards..Power.distributed.throughout.a.commercial.or.

industrial.application.is.used.for.a.variety.of.applications.such.as.

heating,.cooling,.lighting,.and.motor-driven.machinery.

Outdoor

Feeder

Busway

Feeder Busway

480 VAC

From Utility

480 VAC

Switchboard

Panelboard

Transformer

480 VAC

120 VAC

480 VAC

Panelboard

Motor Control Center

Basic Motor Control .

Wherever.motors.are.used,.they.must.be.controlled..In. Basics

of Control Components .you.learned.how.various.control.

products.are.used.to.control.the.operation.of.motors..The.most.

basic.type.of.AC.motor.control,.for.example,.involves.turning.

the.motor.on.and.off..This.is.often.accomplished.using.a.motor.

starter.made.up.of.a.contactor.and.an.overload.relay..

The.contactor’s.contacts.are.closed.to.start.the.motor.

and.opened.to.stop.the.motor..This.is.accomplished.

electromechanically.using.start.and.stop.pushbuttons.or.other.

pilot.devices.wired.to.control.the.contactor..

The.overload.relay.protects.the.motor.by.disconnecting.power.

to.the.motor.when.an.overload.condition.exists..Although.the.

overload.relay.provides.protection.from.overloads,.it.does.not.

provide.short-circuit.protection.for.the.wiring.supplying.power.

to.the.motor..For.this.reason,.a.circuit.breaker.or.fuses.are.also.

used.

Motor Starter

Circuit Breaker

Contactor

Overload Relay

Type/Tipo

NDG

Frame DG

AC Motor

OFF

150A

Motor

Start

Pushbutton

Stop

Pushbutton

Overload Contact

Contactor Coil

Auxiliary Contactor Contact

(Holding Circuit)

Typically.one.motor.starter.controls.one.motor..When.only.a.

few.geographically.dispersed.AC.motors.are.used,.the.circuit.

protection.and.control.components.may.be.located.in.a.panel.

near.the.motor.

Short Circiut

Protection

Disconnect

OFF

START

STOP

Motor Starter

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