Espec Para Arrancador Con Resistencia Liquida

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DS SPEC 581005

Document status Approved Copyright

ISSUE 0 4 J anuary 2008 of 17

Debswana Specification

Electrical

Enhanced Liquid Resistance StarterConfiguration for Grinding Mills



DS SPEC 581005



CONTENTS PAGE

1 SCOPE 3 2 TECHNICAL REQUIREMENTS TO BE SPECIFIED BY THE ENGINEER 3 3 TECHNICAL DATA TO BE REPORTED BY THE CONTRACTOR 3 4 DEFINITIONS 3 5 REQUIREMENTS 5 5.1 OPERATION OF THE ENHANCED LRS 5 5.2 ENVIRONMENT 5 5.3 DETERMINATION OF ENERGISATION RESISTOR, 1ST STAGE & 2ND STAGE LRS

RESISTANCES 5 5.4 ENERGISATION RESISTOR 5 5.5 CONTACTORS 6 5.6 LRS CONTROL 6 5.7 CURRENT TRANSFORMER 6 5.8 ELECTRODE PHASE T ANK CIRCULATING PUMPS 7 5.9 MONITORING 7 5.10 SECOND STAGE LRS ELECTROLYTE HEATER 7 5.11 ELECTRODES 7 6 QUALITY ASSURANCE PROVISIONS 7 7 TEST, INSPECTION METHODS 7 8 MARKING 8 9 PACKING 8 APPENDIX A: RELATED DOCUMENTS 9 APPENDIX B: RECORD OF AMENDMENTS 9 APPENDIX C: SINGLE LINE DIAGRAM OF A TYPICAL ENHANCED LRS FOR ADUAL- PINION MILL 10 APPENDIX D: LOGIC FLOW DIAGRAM (HIGH LEVEL) 11 APPENDIX E: SPECIAL REQUIREMENTS 13 APPENDIX F: DATA TO BE SUPPLIED BY THE ENGINEER AND THECONTRACTOR FOR THE PROJECT AND FOR EACH MILL & DRIVE TYPE 14 APPENDIX G: COMPLIANCE WITH THE SPECIFICATION 17



DS SPEC 581005



1 SCOPE

This document specifies technical issues unique to the enhanced liquid resistance starter

(“LRS”) configuration for grinding mills. This configuration will reduce torsional stressesduring starting large mills. (Refer to Debswana Specification 581006 “Torque Limits ForGrinding Mill Drives”.) An enhanced LRS comprises two LRS in parallel plus an optionalseries energisation resistor per motor. Thus an enhanced LRS for a dual pinion millcomprises four individual LRS in total. (Refer to the single line diagram in Appendix C.)

This specification only addresses those aspects that are unique to an enhanced LRSconfiguration; standard requirements for the starter shall be covered by otherspecifications (see Appendix A).

2 TECHNICAL REQUIREMENTS TO BE SPECIFIED BY THE ENGINEER

The following requirements shall be specified on every invitation to tender, contract, ororder:

• Title, number, issue and date of this specification.

• Technical data in Appendix F.

3 TECHNICAL DATA TO BE REPORTED BY THE CONTRACTOR

The contractor shall specify the data as required in Appendix F.

Note that the engineer shall specify his requirements in the first column and the contractorshall state the capabilities of the equipment that he is offering in the second column of thesame Appendix.

In Appendix G, the contractor shall indicate compliance or acceptance of each clause of this specification.

4 DEFINITIONS

For the purpose of this specification the following definitions shall apply (refer to the singleline diagram in Appendix C):

Approved : Approved by the Engineer in writing

Closed Loop Control : An LRS control system, whereby the LRS electrode

movement is stopped (i.e. the LRS resistance ceases todecrease) if the rotor current exceeds a pre-set value.

Cold : Condition of the starter at the coldest ambient before anystart is performed.

Dual LRS : Arrangement for dual pinion mills, whereby two LRS sharecommon electrolyte, electrode carriages are moved by acommon drive and the contactor is ganged, all to ensureload sharing throughout the start.



DS SPEC 581005



Energisation Resistor : A resistor in series with the first stage LRS for the first onesecond (adjustable) after the motor(s) are energised.

Enhanced LRS : Arrangement of two LRS per motor to achieve a greaterresistance variation during the start so as to reducetorsional transients. (Refer to the single line diagram inAppendix C and Logic Flow Diagram Appendix D.)

First stage LRS : The LRS (single or dual unit) that is connected to the sliprings of the main motor(s) to accelerate it (them) from zeroto approximately 97% speed. At the end of the travel of thefirst stage LRS’ electrodes, a contactor connects the sliprings and first stage LRS to the second stage LRS in aparallel connection. (Refer to the single line diagram in

Appendix C and the Logic Flow Diagram Appendix D.)

Hot : Condition of the starter and components, in the hottestambient, immediately before performing the last of thespecified maximum allowed number of starts per hour.

LRS : Liquid Resistance Starter. In this specification, in the caseof single pinion mill LRS means a single LRS. In the caseof a dual pinion mill LRS means a dual LRS.

OEM : Original Equipment Manufacturer

Second stage LRS : The LRS (single or dual unit) that is connected to the sliprings of the main motor in parallel with the first stage LRSat the end of the operation of the first stage LRS, when themotor has reached approximately 97% speed. The secondstage LRS accelerates the motor to close to rated speed,when a contactor short-circuits the slip rings. The motormay run permanently at rated speed with this short-circuitcontactor, or a rotating slip ring short-circuit hub and brushlifting gear may be operated after the short circuit contactorhas operated. (Refer to the single line diagram in AppendixC the Logic Flow Diagram Appendix D.)

QAP : Quality Assurance Procedure

VSD : Variable speed drive

The following terms are defined in the General Conditions of Contract:

• Debswana, Company, Contractor, Engineer.

Confidentiality and Indemnity as well as Proprietorship and Copyright are in accordancewith the conditions of contract.



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5 REQUIREMENTS

5.1 OPERATION OF THE ENHANCED LRS

Refer to the definitions for a brief description of the terms and to the single line diagram inAppendix C the Logic Flow Diagram Appendix D.

When the motors are energised, an energisation resistor in series with the first stage LRSlimits the motor starting current. After approximately one second (adjustable) theenergisation resistor is short-circuited by contactor 1 / 1A. Simultaneously, the first stageLRS electrodes begin to be lowered.

The first stage LRS now accelerates the motor to approximately 97% speed. When thefirst stage LRS completes its operation, contactor 2 / 2A connects the second stage LRSin parallel with the first stage LRS.

The operation of the second stage LRS is initiated by closing contactor 2 / 2A. The secondstage LRS accelerates the motor from approximately 97% speed closer to rated speedand then contactor 3 / 3A short-circuits the slip rings. The slip rings shall be short circuitedonly after a one second delay after the second stage electrodes complete their travel.

This arrangement achieves a wider range of resistance in the rotor circuit than does asingle LRS and hence achieves lower transient torques during starting.

5.2 ENVIRONMENT

All equipment shall be suitable for the environmental conditions specified by the engineerin Appendix F.

5.3 DETERMINATION OF ENERGISATION RESISTOR, 1ST STAGE & 2ND STAGE LRS

RESISTANCES

During contract execution of each new mill and or drive design, before manufacturecommences, a simulation study shall be performed. This study shall encompass thesupply network, main mill motor(s), resistor starting system, shafts, couplings, gears, milland ore. The study shall be performed at maximum supply voltage (refer to Appendix F)and for both cold and hot conditions. The various parameters of the starter system shallbe optimised to ensure that the torsional stresses imposed on the mill mechanicals arewithin the limits stated in Debswana Specification 581006 “Grinding Mill Torque Limits.”

On completion of the simulation study, before manufacture commences, the schedule inAppendix F of this specification as well as the relevant Appendices in Specification581006 shall be completed and submitted to the Engineer for his approval.

5.4 ENERGISATION RESISTOR

The energisation resistor shall be rated for:

• 110% of rotor rated current

• Constant duty cycle of two seconds on and fifteen minutes off (1/450)

• Full rotor phase voltage line to earth.

The resistor shall:



DS SPEC 581005



• Be monitored with an over temperature alarm.

• Be protected with temperature sensor that will inhibit a start on excessive

temperature.• Have taps as specified in Appendix F. It shall be possible to easily change the

resistance values on site by either cabling all the taps down to terminals, orconnecting the terminals by “loops” of silicone insulated cable to terminals in such amanner that the cables may be readily moved to other taps or all taps shall bebrought down by bus bar to a termination point.

• Tested at twice rotor open circuit voltage divided by 1,7 plus 1 kV to earth for 60seconds.

• Be short circuited after a pre-set time from the instant that the mill motor is started,as determined by the liquid resistance starter and not under the control of the plantplc (as the latter can introduce uncontrollable delays).

5.5 CONTACTORS

For dual starters all rotor switchgear shall be mechanically ganged so as to ensure theclosest possible synchronism between the switching operations of both motors.

All contactors in the rotor circuit (contactors 1/1A, 2 /2A, 3/3A in Appendix C) shall berated at least:

• Full rotor open circuit voltage

• 200% of rotor current for sixty seconds

• Open on-load 200% of rated rotor current as dc

In addition, if slip ring short-circuiting and brush lifting gear is NOT installed, the short-circuiting contactor (ganged if the starter is a dual LRS, for dual pinion drives) shall berated for at least 120% of the rotor current continuously.

5.6 LRS CONTROL

If specified by the engineer in Appendix F, the first stage LRS shall include closed loopcontrol; otherwise the setting time shall be fixed. The closed loop control shall not causethe electrodes to be raised, but shall act only to prevent the electrodes from being loweredwhile the rotor current exceeds 150% (adjustable) of the rated current.

The setting time of the second stage LRS shall include a VSD on the electrode drive toallow the setting time to be pre-set during commissioning.

5.7 CURRENT TRANSFORMER

If closed loop control is required, a Hall – Effect CT rated dc to 50 Hz and zero to 200% of rotor rated short circuit current shall be installed in the first stage LRS to monitor rotorcurrent.



DS SPEC 581005



5.8 ELECTRODE PHASE T ANK CIRCULATING PUMPS

Each of the three polypropylene electrode phase tanks in the first stage starter (only) must

have the entire electrolyte within it exchanged within five minutes. This is to be done by apump(s), draining from two locations, on opposite sides of and on the bottom of eachelectrode tank, and returning the hot electrolyte far from the electrode phase tanks,slightly below the surface of the electrolyte. The electrode phase tank pump(s) mustoperate for fifteen minutes after a start, before a “start interlocks healthy” can be issued.

The pump(s) must cease operating when a start commences.

An electrolyte-circulating pump is not to be installed in the second stage liquid resistancestarter.

The pumping arrangement shall be submitted to the Engineer for his approval beforemanufacturing commences.

5.9 MONITORING

The electrolyte temperature shall be monitored by a temperature sensor mounted close tothe outlet of the electrode tank pump mention in clause 5.7 above.

An alarm, indicating that only one more start is permitted, shall be issued when theelectrolyte temperature exceeds 35 ºC (adjustable). Further starts shall be inhibited whilethe electrolyte temperature exceeds 45 º C (adjustable).

5.10 SECOND STAGE LRS ELECTROLYTE HEATER

The second stage liquid resistance starter shall be equipped with a thermostatically

controlled immersion heater rated to maintain its electrolyte at an (adjustable) temperatureof between 20 ºC and 25 ºC.

5.11 ELECTRODES

The electrodes of both the primary and secondary liquid resistance starters shall mesh byat least 100 mm or more.

Electrodes on starters of machines rated above 3,6 MW shall be no smaller than EPM 4/2.

6 QUALITY ASSURANCE PROVISIONS

Debswana QAP100 shall apply.

7 TEST, INSPECTION METHODS

The Enhanced LRS shall be subjected to OEM FAT and the full function of the EnhancedLRS shall be proved. The results of all tests shall be recorded.



DS SPEC 581005



8 MARKING

In addition to the requirements of the standard specification, a nameplate shall be affixedto every starter. This nameplate shall have the following information:

• Enhanced Liquid Starter System.

• Identification of specific role of the equipment, e.g. Dual starter as well asenergisation resistor, first or second stage LRS.

• Motor rated power, rotor voltage and rotor current.

• Setting time range.

• Closed Loop Control (if installed; first stage starter only).

• (Ganged for dual LRS) Contactor current and voltage rating.

• Number of starts per hour.

9 PACKING

Refer to standard specification.



DS SPEC 581005



APPENDIX A: RELATED DOCUMENTS

The latest version of the following shall apply:

Debswana Specification 581006 : Grinding Mill torque limits

Debswana specification QAP100 : Quality management systems for critical and majorproducts

Anglo Platinum Specification AEL003 : Liquid Starters for Electric Motors

APPENDIX B: RECORD OF AMENDMENTS

Issue 0 : Based upon AAC specification



DS SPEC 581005



APPENDIX C: SINGLE LINE DIAGRAM OF A TYPICAL ENHANCED LRS FOR A DUAL-PINION MILL



DS SPEC 581005



APPENDIX D: LOGIC FLOW DIAGRAM (HIGH LEVEL)

The following offers an overview only of the LRS operation to clarify the operation of the two LRS’that comprise the enhanced LRS system. The normal LRS sequence and control will apply to theindividual LRS. Thus LRS “starts interlocks healthy” condition requires:

• Electrode tank pumps to have operated for fifteen minutes since the last start

• All electrodes to be at the top position

• (Ganged if dual LRS) energisation resistor short-circuit contactor to be open

• (Ganged if dual LRS) contactor in 1st stage LRS to be open

• (Ganged if dual LRS) short-circuit contactor in 2nd stage LRS to be open

• Electrolyte temperatures to be below start inhibit levels

• Etc.



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DS SPEC 581005



APPENDIX E: SPECIAL REQUIREMENTS

The following additional notes shall apply for Waterval UG2 Concentrator secondary Mill:

The dual starter from the primary mill to be refurbished and utilized as the 2nd stage LRS. Thisrequires that the electrode drive gearbox be removed, and a larger VSD driven motor be installed.

The existing dual starter is to have “closed loop” control installed. This will necessitate installing aHall Effect CT, larger power VSD driven electrode travel motor, plc

The energisation resistor (one per motor) could be mounted on either the existing dual LRS or onthe refurbished LRS.

For Waterval, the energisation resistor, first and second stage resistance values have beencalculated by ATD. Thus the requirements of clause 5.3 have already been complied with and the

cost of a study should not be included in the LRS equipment quote.



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APPENDIX F: DATA TO BE SUPPLIED BY THE ENGINEER AND THE CONTRACTOR FORTHE PROJECT AND FOR EACH MILL & DRIVE TYPE

Notes:

a) The Engineer and the Contractor may find it useful to refer to Debswana Specification 581006:Torque Limits for Grinding Mills when completing this Appendix.

b) Not all data wi ll be available at the tender stage, but will be required at the cont ract stage.

APPENDIX F: DATA TO BESUPPLIED BY THE ENGINEERAND THE CONTRACTOR FOR

THE PROJ ECT

CLAUSENO

TO BECOMPLETEDBY ENGINEER

TO BE COMPLETED BY THE CONTRACTOR

Drive

Single or Dual pinion mill Dual

Motor rating [kW] 5 200

Rotor open circuit Voltage [Volts] 1 958

Rotor rated current [Amps] 1 578

Number of evenly-spaced starts[/hr]

4

Environment

Altitude [masl] 1 650

Ambient temp – max [°C] 40

Ambient temp – min [°C] 0

Tolerance on voltage +/-10%

Humidity

Dusty Dusty

To be completed during contract execution, after completion of a simulation study, beforemanufacture commences:

Energisation resistor

Resistance [Ohms per phase] 0,6

Taps [Ohms per phase]0,4 0,5 0,60,7 0,8

Energy rating [MJ / phase] 4,8



DS SPEC 581005




THE PROJ ECT

CLAUSENO

TO BECOMPLETED

BY ENGINEER


Power rating [MW / phase] 2,4

Duty cycle [secs on / minutes off] 2 / 15

Current rating (110% of rotornominal) [Amps]

1 736

1st stage LRS:

Initial resistance [Ohms at 15 ºC] 1,0

Electrolyte concentration [kg/tank] By contractor

Setting time [secs] 20-30

Setting time range [secs] Fixed time

Closed Loop Control:

Closed loop control required[yes/no]

Optional pricerequired

Leine & Linde type 861–008516-

2048-RS 4322 shaft angularposition encoder [yes/no]

No

Toothed wheel with least 20 pulsesper revolution [yes/no].

Optional pricerequired

2nd stage LRS:

Initial resistance [Ohms at 15 ºC] 0,11

Electrolyte concentration [kg/tank] By contractor

Setting time [secs] 6

Setting time range [secs] 4 – 10

Torque transients

At energisation (cold) [% of motorrated torque]

NA

When short-circuit energisationresistor (cold) [% of motor ratedtorque]

NA



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THE PROJ ECT

CLAUSENO

TO BECOMPLETED

BY ENGINEER


When short-circuit energisationresistor (hot) [% of motor ratedtorque]

NA

When short-circuit slip rings (hot)[% of motor rated torque]

NA



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APPENDIX G: COMPLIANCE WITH THE SPECIFICATION

Note:

a) The Contractor shall complete this Appendix to indicate his compliance or otherwise with eachclause of this specification. Failure to complete this form may result in the tender beingdisqualified.

APPENDIX G: CLAUSE NO.

TO BE COMPLETEDBY THE

CONTRACTOR

Comply


Do not comply

3

5.2

5.3 N/A

5.4

5.5

5.6

5.7

5.8

6

7

8

9

Appendix C

Appendix D

Appendix E

Appendix F

Appendix G

Espec Para Arrancador Con Resistencia Liquida

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