02 Motor de Anillos

Curso de capacitacin GMDRingmotor

ABB University Chile, Noviembre 2012

Contents

Brief history/overview of GMDs Installed base Synchronous motors Insulation systems Ringmotor design

ABB Group November 16, 2012 | Slide 2

Ringmotor design Ringmotor components Ringmotor manufacturing

Fame, laminations, winding, poles, sealing, cooling Instrumentation: Air gap (stationary and rotating), PD

Summary

GMD System overview

T1 T1T1

S

T2

Converter transformer

Cycloconverter & excitation

E-house &

Harmonic filter & power factor compensation


SMie

iT

n2

B

A

u+

u-

n1

iR

uR uSuT

iS

i+

i-

3 Ringmotor

excitation Auxiliaries

Controller (drive control, system control)

History, overview of GMDs

In the sixties the cement process started to be controllable, requirements of large cement and raw mills came up

The cement plant Le Havre in France, was the biggest and most advanced cement plant at that time in1969

It was the first straight single line cement plant at that timeSingle cement mill of 160 metric tons / hour was required


Single cement mill of 160 metric tons / hour was required No gearbox manufacturer could supply a gearbox for this

size of power BBC (later ABB) came up with the idea of a Gearless Mill Drive

(GMD) of 6400 kW BBC was awarded to supply the first GMD in 1969 Le

Havre/France

History, overview of GMDs (cont.)

The first GMD was running with its original design from 1969 until 2000 and continuous with a new power part (cycloconverter) its operation under full production

Le Havre GMD was controlled by the last generation of mercury rectifiers

Since successfully beginning operation at the end of 1969,


Since successfully beginning operation at the end of 1969, this first GMD in the world, operating with a cycloconverter fed synchronous motor, has been followed by much more such drives, firm confirmation that BBC were on the right path

Competition came later into the game when performance data from BBC was visibly very positive

BBC delivered first GMD for the mining industry in 1970 to the Bougainville plant in Papua New Guinea

Recently ordered and installed base


Installed Base - Collahuasi, Chile


General

No upper design limit to the rated output High power, huge capacity & throughput Drive is constructed with a single motor The air gap can be made sufficiently large This allows the rotor to be mounted directly on the rotating


This allows the rotor to be mounted directly on the rotating part of the mill body

Large air gap permits large air gap variations Motor to operate at unit power factor

Basic GMD data

Motor type: Synchronous motor Power range: 528 MW Altitude: 4600 m.a.s.l. Speed range: 015.5 rpm Motor poles: up to 76 poles


Motor poles: up to 76 poles Motor torque: up to 28000 kNm Motor frequency: 0 5.8 Hz Motor voltage: 0 5730 V ac Motor current: 0 2500 A Excitation current: 0 700 A dc

Basic GMD data (cont.)

Motor weight: up to 650 tons Pole weight: up to 3 tons Motor height: up to 20 m Motor cooling: air or water cooled Motor air gap: 12.5 22 mm


Motor air gap: 12.5 22 mm Motor lifetime: up to 40 years or even more

System advantages

No gear box Minimum number of mechanical components Minimum number of electrical components Only two wearing parts - brushes and dry sealing No inching drive required


No inching drive required Variable speed, the base for process optimization Low maintenance

High availability & reliability Bi-directional operation possible

Synchronous motors

Can be used in a very wide range (due to its possibilities of adjustment)

Higher efficiency than induction motors Less voltage drop during start-up Number 2 with respect to number of drives


Number 1 with respect to output Its a working horse !

Synchronous motors - fields of application

Compressors (turbo or reciprocating) Pumps Wind tunnels Mills ! Wood grinders


Hot rolling mills Hoist drives Excavators Tunnel bore machines T-Bar drive (winter sport) Vertical roller mills And more

Synchronous motors (cont.)


Synchronous motors - Turbo-compressor rotor


Synchronous motors - Reciprocating compressor rotor


Synchronous motors - Mill drive rotor


Synchronous motors - components


Synchronous motor - basics

Rotational speed n = n0 = f1/p (synchronous speed) Slip s = 0 Stator with 3-phase AC winding DC excitation for rotor winding (excitation current IF)

Either by an external DC generator or by a rectifier


Either by an external DC generator or by a rectifier Current to the rotating field windings carried by brushes

and slip rings Alternative: brushless excitation with diode bridge

Synchronous motor basics (cont.)

Cylindrical Motor


Salient Pole Motor


Cylindrical Typically used for higher speeds (windage losses,

noise) Often 2 pole design, e.g. turbo-generators (50 or 60 Hz)

with 3000 rpm or 3600 rpmLong rotors


Long rotors Cylindrical rotor design

Solid rotor (2p = 2 or 4) Laminated rotor (2p 6)


Salient pole Typically used for lower speeds Larger number of poles Single poles feasible due to lower centrifugal forces Large diameter, short axial length


Air gap not constant over circumference Salient pole rotor design

Solid poles (with or without damper rings) Laminated poles

With complete damper winding With damper cage Nothing

Synchronous motor Stator core and frame


Synchronous motor Salient pole rotor (14P)


Synchronous motor Salient pole rotor (4P)


Synchronous motor Damper winding

Mechanical or electrical load variations can lead to torque oscillations

This results in torsional vibrations and oscillations in the current

The motor may fall out of synchronizationDamper winding


Damper winding Damper winding is similar to cage of induction motor Dampens these oscillations Higher harmonics and resulting losses Used to start synchronous motors similar to induction

motors

Synchronous motor Damper Winding (cont.)


Synchronous motor Slip rings on ringmotor


Synchronous motor Slip rings on ringmotor (cont.)


Synchronous motor Reactive power

Over-excitation Generates reactive power Motor acts as capacitor

Under-excitation Uses reactive power


Uses reactive power Motor acts as inductor

Sometimes used as phase shifting element to generate reactive power needed for transformers and induction motors

Synchronous condensor

Synchronous motor Power factor diagram

U1

U

Uh

jXh I1

jX I1

U1

U

.

Uh

jXh I1jX I1


Up

.I1

I

jX I1

Up

I1

I

Inductive (Lagging PF) Capacitive (Leading PF)

Synchronous motor Frame of reference

+ q axis- q axis+ d axis


- d axis

d: direct axis (in excitation direction) q: quadrature axis (in torque direction)

Synchronous motor Equivalent circuit


Quadrature axis (q)Direct axis (d)

Synchronous motor Unbalanced magnetic pull

Depends on magnetic flux (distribution) Occurs when the rotor is eccentric (out of center) Can also occur from magnetic flux asymmetry Force is destabilizing Use of parallel paths in motor stator windings can reduce


Use of parallel paths in motor stator windings can reduce UMP effects

Insulation systems

Temperature often the dominating ageing factor Thermal classes (IEC 60085)

Maximum appropriate temperature Class B 130C Class F 155C


Class F 155C Other factors of influence

Mechanical stress, vibration, different thermal expansion

Moisture, dirt, chemicals, contaminants

Insulation systems (cont.)

Temperature rise (IEC 60034) Difference of temperature of part and temperature

of coolant Maximum ambient air temperature: 40C Temperature rise is reduced if coolant temperature

exceeds 40C


exceeds 40C Class B 85K

Motor winding is only a single turn winding; no interturn failure possible

Temperature rise typically only approximately 50C

GMD Operating parameters


GMD - Mill diameters and power (typical)

> 25 feet: typically SAG Mills Pedestal Mounted Ringmotor

15 MW SAG Mills 28 MWMill Cylinder


25 feet: typically Ball Mills Foot Mounted Ringmotor

8 MW Ball Mills 22 MW

GMD Mill speed

Critical Speed speed at which the centrifugal

force is big enough that the material sticks to the mill shell and therefore no grinding effect occurs.


Mill internal diameter definition depends on the mill supplier:

Shell to Shell Liner to liner

GMD Mill speed on grinding process


GMD Mill speed on grinding process (cont.)

SAG Mills: Rated Speed is btw. 74 % and 80 % of Mills Critical Speed Max. Speed is btw. 80 % and 85 % of Mills Critical Speed 8 RPM Rated Speed (RS) 11 RPM (Typical)

Ball Mills Rated Speed is btw. 74 % and 80 % of Mills Critical Speed


Rated Speed is btw. 74 % and 80 % of Mills Critical Speed Max. Speed is btw. 80 % and 85 % of Mills Critical Speed 11 RPM Rated Speed (RS) 14 RPM (Typical)

Mill Speeds related parameters 0.3 Hz GMD Operating Frequency 6 Hz Number of Rotor poles

48 to 76 poles (or more) The bigger the Mill diameter the lower the Critical Speed

the higher the number of Rotor Poles

GMD Efficiency, operation

Motors have a high efficiency Less number of poles than other designs Low cooling air flow

Motor is running very soft; no unbalanced torque can be noted (measured with the mill bearing pressure device)


Isolation switches for rotor and stator are directly built onto the main terminal box

Only a 3 phase winding in the stator used (no parallel circuits); no uncontrolled torque possible

GMD Mechanical design

Motor is rigid Less deformation of the stator More flexibility for the mill manufacturer

Motor poles can be individually adjusted All torques and forces from rotor to mill flange only by


All torques and forces from rotor to mill flange only by friction (no shear forces)

Good access to the liner bolts directly below the motor Advanced sealing system (axial spring loaded dry system) Motor heat exchanger not fixed to the motor housing. No

vibration will be transferred

GMD Ringmotor

Typical SAG Mill design Typical Ball Mill design Manufacturing

Frame Stator core pack


Windings Poles and pole fixing Sealing Cooling Instrumentation

Air gap measurement Partial discharge

Pedestal mounted motor


Typical SAG mill arrangement


Typical SAG mill arrangement (cont.)


Antamina SAG mill


Century Zinc SAG mill


Foot mounted motor


Typical Ball mill arrangement


Typical Ball mill arrangement (cont.)


Antamina Ball Mills


Cerro Verde ball mills


Manufacturing

Stator frame Stator laminations Stator winding Rotor poles Sealing system


Sealing system Overpressure fans Cooling circuit Instrumentation

Air gap sensors Partial discharge monitoring

Stator frame


Stator frame (cont.)


Stator laminations


Stator lamination stacking


Stator lamination stacking (cont.)

First lamination 2 mm carbon steel plate

Remaining laminations 0.5 mm non grain orientated silicon steel



First package of laminations glued together with resin

Same resin as the windings, slightly diluted to reduce viscosity



Keybars, hanging plates and first set of laminations.



Lamination being stacked.


Lamination at stator partition.

Stator lamination pressing


Stator lamination pressing (cont.)


Stator winding - Slot fill

Upper Wedge

Ripple Spring

Lower wedge, packer

Main insulation with


Main insulation with

Outer corona protection

Separator or RTD

Round Packing

Inner corona protection(if necessary)

Stator winding Automatic taping


Stator winding - Bars


Stator winding Bars ready for insertion


Stator winding - Stator bar insertion


Stator winding - Wedging


Stator winding End connections


Stator winding End connections (cont.)


Stator winding - Stator terminals


Rotor Pole


Rotor Pole (cont.)


Pole mounting


Pole mounting (cont.)


Rotor pole


Rotor pole arrangement


Rotor pole arrangement (cont.)

Slip rings


Face forteflon seal

Rotor cover

Central fixation bolt

Mill flange Eccentric bushings

Lateralfixation bolt

Pole central plate

Rotor cover

Rotor pole arrangement (cont.)

Slip rings


Face forteflon seal

Rotor cover

Pole bolt with eccentric bushing

Mill flange

Central fixation bolt

Rotor pole - Manufacturing


Rotor pole - Pole units prior to impregnation


Sealing system


Sealing system (cont.)

Stator cover

Inside motor


Rotor cover Spring

Mechanicalprotection

Rubber seal

Sealing lip

Sealing lip

Teflon spacers

Inside mill

Inside motor

Sealing system (cont.)


Sealing system: Over-pressure fans


Sealing system: Over-pressure fans

2 fans with ~2 kW each To generate over-pressure

inside the motor Typical values:

400 Pa static pressure 1 m3/s air flow


1 m3/s air flow At site altitude

Keep dust out of the motor Symmetric design Filter cartridge

1 10 m Water resistant

Sealing system: Type 3 filter cartridge


Motor cooling


Motor general cooling arrangement

Air to water

Fan

Air


ACMotor

Air

Heat Exchanger

Water

Motor general cooling arrangement (cont.)

Air to Water Air

Fan

Air

Fan


Air

Heat Exchanger

ACMotor

Motor general cooling arrangement (cont.)

Air to Water to Air

FanFan

AirAir


Heat Exchanger Heat Exchanger

Air

WaterAC

Motor

Motor cooling systems: Chillers


Ringmotor instrumentation Stationary air gap sensors

Terminal Box


Terminal Box

Stationary air gap sensors (cont.)

3 static sensors Redundancy Alarm- and trip levels of the

air gap Normal operation


16 mm, rotor centered Alarm

Out of center by 4 mm Trip

Out of center by 5 mm

Stationary air gap sensors - conditioner box


Stationary air gap sensors - Air gap measurement

Measuring method: Contactless, capacitive

Scale range: 0,5 - 100 mm (depending on

probe dimensions) Accuracy:


Accuracy: 2% approx.

Temperature range: 0C ....... +125C

Probe: 120 x 90 x 2 mm

Meter amplifier: 190 x 120 x 60 mm

Ringmotor instrumentation - Rotating air gap measurement


Rotating air gap measurement (cont.)

Rotating sensor installed on a rotor pole, e.g. Pole # 1. Same sensor type as static system Transmitter and antenna installed on rotor cover Power for transmitter supplied from rotor poles suitably

transformed and protected.


Digital signal transfer between transmitter and receiver Frequency 2.4 GHz Receiver installed outside stator frame . As close to line of

sight installation for optimum signal. Key phasor (proximity sensor) installed on motor to

develop actual rotor pole position.

Rotating air gap measurement - Transmitter


Rotating air gap measurement Probe and Conditioner


Rotating air gap measurement Antenna


Rotating air gap measurement - Visualisation


Rotating air gap measurement Visualisation (cont.)


Instrumentation - Partial Discharge (PD) Monitoring

During operation the insulation system of any electric motor is subjected to a number of stresses.

On-line partial discharge allows PD activity to be recorded whilst the GMD is subjected to normal operating stresses:

Thermal winding temperature, thermal cycling, etc

Electrical grid over-voltage, discharges in voids, etc.


Ambient humidity, oil, carbon dust, etc.Mechanical vibrations, electromagnetic forces, etc.

On-line partial discharge is an additional measurement tool to assess the integrity of the insulation of the GMD without having to shut the GMD down.

Important terms: On-line versus off-line Continuous versus time interval measurements

PD possible areas of discharge


PD - Mechanisms

PD is a local breakdown phenomenon of microscopic voids causing small sparks.

PD produce high frequency signals as a superposition to the line voltage.

The high frequency signals can be measured by installing couplers.


couplers. Patterns gained from measurements allow identification

and localization of insulation defects and upcoming failures.

Over time PD has an ageing effect on the insulation.

PD - Typical schematic


PD - Components

One per phase, one in neutral for noise filteringType CC7, 1000 pFIEC 60034-27 gives guidelines for value of coupling capacitor capacitance to be at least 1000 pF.Allows safe and consistent hook-up point for measurement.


measurement.

Surge protected to 90 V

IP65 enclosureClosed during normal mill operation

MICAMAXX pdplus portable measurement deviceUse for all installations

On-line PD measurements

Takes 30 seconds per phase measurement Accomplished in approximately two minutes Ringmotor is RUNNING (on-line measurement)

Thermal equilibrium (constant full load) Rated Voltage


Rated Voltage Rated Speed Measured humidity Measured winding temperature Measured current/load and voltage Allows for subsequent measurement comparisons

PD - Typical report information


PD - Typical report (cont.)

Specific report per measurement instance. PD measurement is a trending tool. Can compare subsequent measurements and be able to

advise future of the insulation. Can advise suitable preventative maintenance measures,

e.g. clean the end winding from contamination.


e.g. clean the end winding from contamination. Made more valuable when coupled with additional

measurement methods.

Summary, recap

Brief history/overview of GMDs Installed base Synchronous motors Insulation systems Ringmotor design


Ringmotor design Ringmotor components Ringmotor manufacturing

Fame, laminations, winding, poles, sealing, cooling Instrumentation: Air gap (stationary and rotating), PD

02 Motor de Anillos

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