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Post by John on Feb 8, 2013 16:15:50 GMT -5
Doesn't seem that long since the old NCB fought tooth and nail for 1100 volts at the working face, now there are 11Kv faces in Australia.
I worked on faces supplied with 11Kv, but the face machinery was still 1100 volts.
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Post by Wheldale on Feb 8, 2013 17:19:35 GMT -5
What held back the faces for the NCB? Was it HMI? Also, was there an era when there was a boom in new technology? Or has it just progressed slowly?
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Post by John on Feb 8, 2013 17:35:36 GMT -5
Doesn't seem that long since the old NCB fought tooth and nail for 1100 volts at the working face, now there are 11Kv faces in Australia.
I worked on faces supplied with 11Kv, but the face machinery was still 1100 volts.
It was only after Sensitive Earth Leakage (SEL) came into being in the mid 60's that the Inspectorate would give exemptions to the Act and then only at mines who had no to low methane problems.
Not sure if the Act was changed or exemptions to the Act allowed the NCB to go ahead installing 1100 volt equipment at the face.
Also, mobile machinery was restricted by the Act to a maximum of 660 volts, so the shearer was the main problem to gain exemptions for. Trailing cables were notorious for causing showers of sparks, hence the nervousness of the Inspectorate.
I'd hate to have to work on an 11Kv trailing cable, they would be enormous!! The ones we had feeding the transformers on the Pan Tech at Angus place were about 8 inches diameter!!! Jeeze they were heavy!! |
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rob52
Shotfirer.
Posts: 199
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Post by rob52 on Jun 22, 2013 5:29:36 GMT -5
Regarding the Application of 3.3kV in UK Coal Mines.
Looked through my copies of Mining Technology, Journal of AMEME which became IMEMME:
[Part 1]
May 1969 Mining Technology
"Coal Face Voltage - The Choice" by J F Wilkie
" * It compares the relative performances of 565V, 1,100V & 3,300V for Face Machinery.
* It notes that 4,160V Machines and 1,000V were being introduced to American Mines.
* Comments on the NCB Spec for 50, 65 & 120HP AFC Motors.
* The NCB must now seriously consider the design of 3.3kV equipment so that some standardisation of dimensions and control duty requirement will be possible before too many varieties are utilised.
* it will be necessary to resolve an approved design of flexible 3.3kV Trailing Cables.
* A change to 1100Volts is relatively easy, as equipment is available and the design aspects for the motors are similar to 550 volts. If it is contemplated that 3300V will be utilised it will be essential to formulate some development work. The design, development and delivery of 3.3kV switchgear of a more compact, flexible and comprehensive arrangement could take five years. If a quicker change to 1,130 volts had been undertaken the economics of changeover would have been easier. The next step is to 1,130volts applied to both advancing and retreating systems of mining.
"
[Part 2]
April 1990 Mining Technology
"Application of 3.3kV at the Coal Face" - ES Entwisle Manager Electrical Engineering, British Coal Corporation Headquarters Technical Department.
"During the early 1960's it was realised that the then standard utilisation voltage of 550V was inadequate to deal with the increase in size of face equipment….resulted in the decision to increase the utilisation at the face voltage to 1100V. The choice was influenced by the ease with which motors could be wound so as to be suitable for use on both the old and new voltage with the minimum of redesign and was achieved by the use of a series/parallel arrangement using a Delta Connection. Further more all the existing cables were suitable for use at the new voltage. During 1971, with approximately 170 of the then 800 faces operating at 1100V, engineers were already expressing concern that a further increase in the utilisation voltage would be required….It was concluded at the time that the obvious choice should be 3.3kV because of extensive experience in its use outbye.
There was little evidence of any further developments until the late 1970's when with the introduction of 300kW machines and 225kW AFC Drives, the suitability of 1100V was again questioned. During 1978, tentative consent was given for a field trial of 3.3kV equipment at the coal face. Two sites Kellingley & Dawmill Collieries were selected. The trial at Kellingley was restricted to the AFC and the power loader machines. The Dawmill trial was the AFC only. Subsequent discussions between NCB & HSE ensued, agreement was reached on the requirements to obtain an EXEMPTION from Regulation 7 (i) to permit the use of 3.3kV on portable apparatus. Specifications for all equipment were prepared and budget prices obtained. HOWEVER, "Final Authority for the Trials" was not granted and the Director General of Mining discouraged any further action on the subject.
* Many engineers believed at the time that the opportunity had been missed to prepare for the day when 1100V at the face would become a hinderance.
* Towards the end of 1986, it was acknowledged that no further increase in power rating appeared feasible with the existing 1000V system, following consultation in early 1987 the Technical Director agreed to re-examine the requirement to increase the face utilisation voltage.
* Two UK trial sites were selected, Kellingley & Daw Mill.....the same two sites suggested in the 1970's.
Kellingley's WV33 Face, 2 x 261/522kW two speed AFC Motors 1800t/hr, with an AM500 power loader. Dedicated 6.6kV 185mm2 Cu Feeder to a 6.6kV/3.4kV 1.5MVA 3% Txf @ 500m from the Face. 3.3kV GEB supplied from 500m of 120mm2 T331 cable. The specifications embraced all the desirable features of existing 1100V equipment and took account of experience gained by users and suppliers of 3.3kV equipment abroad. Information was sort from Australia, the United States, South Africa & Germany.
=>> The Face commenced production in February 1989.
"
[Part 3]
February 1991 Mining Technology
"Engineering our way into the 1990's" - A Cutts Head of Engneering & E S Entwisle Manager Electrical Engineering, British Coal Corporation Headquarters Technical Department.
"
The Kellingley trial was successful and plans were made to install an AS Electra 1000 Multi-motor power loading machine operating at 3.3kV in the middle of 1990.
"
Rob.
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Post by John on Jun 22, 2013 6:28:16 GMT -5
An opportunity missed Rob, the biggest hurdle though was HMI who wouldn't readily grant exemptions to the law, especially HV for face machinery...Ironic now, 11Kv is being used in Australia, albeit on the AFC main gate drives, but at least someone is taking the chance and learning from it..
I'd still be very nervous of handling live 11Kv trailing cables, the flexible wired armoured cable we used to feed the two transformers on longwall faces made me VERY nervous..
I once advanced a roof support and caught the fixed section of the shearer cable, the section mounted to the AFC from main gate to the centre of the face, I dread to think what the flash would have been like had it been carrying 11Kv!!
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rob52
Shotfirer.
Posts: 199
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Post by rob52 on Jun 27, 2013 8:45:59 GMT -5
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rob52
Shotfirer.
Posts: 199
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Post by rob52 on Nov 14, 2013 6:31:48 GMT -5
Understand USA has stopped at 4160V? ...now there are 11Kv faces in Australia.
Yes. ..."Blakefield South Mine the world’s first longwall mining operation to use an 11 kV powered armoured face conveyor (AFC) in a hazardous zone,"
Blakefield SouthLW 1 was 325m (LW2 transition to a 405m wide face) Up to 3.5km long blocks Australia's Longwalls Sept 2012 Statistics Listed the following equipment for the Blakefield South LW1 Install: "Joy 7LS-6C DERDS,
Shearer installed Power - 2050kW
2 x 860kW 3.3kV Cutter motors
Cutting Height 3.1m Bi Di
Web Depth 800mm
DERDS Drum Diameters M/G 2.2m & T/G2.2m
2 x 1650kW AFC 11kV Motors (for 325m wide)
3 x 1650kW AFC 11kV Motors (for 400m wide)
AFC 1000mm wide, 50mm twin inboard broadband, 1.81m/s
Joy BSL 600kW 1550mm Wide
Joy Crusher 400kW
Conveyors:
Drift 5,500tph
Trunk 4,500tph
Gate 3,500tph"However the above spec may be the one lost....******************* Ulan West 11-Panel Longwall Project….probably the next to have 11kV AFC Motors? Longwall production to commence 2014 "Joy Global Package
400m wide face
6km long blocks
3 x 1600kW AFC 11kV Motors
possibly another Joy 7LS with 2 x 860kW 3.3kV Cutter motors"
UlanMap of Approved Ulan West Workingsor for those who just like the glossy stuff open-day-showcasesRob |
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Post by John on Nov 14, 2013 6:57:31 GMT -5
Not sure why the US has stopped at just over 4000volts Rob, maybe MSHA won't allow any higher voltages???
That Ulan face will be a big one when it gets running!! I see some record production figures there!
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