Quite large then 
Wot size wire?
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I never quite moved into MW motors (seen them close up though)
Biggest I looked after was 700kW, 3 x 132 kW and a couple of 100kW
(seen them close up though)Biggest I looked after was 700kW, 3 x 132 kW and a couple of 100kW
Work on anything upto 250kW on a regular basis, repairing /overhauling them. Not so much on the installation side.
Did about 3 years on HT stuff upto 11kVa, Trawsffynned Power station was the biggest. We used to stand inside the stator core knocking the slot wedges in. Just over a year ago worked on a 7,400kW motor in a steel scrap merchants. That was a big bugger! On concrete pedastals about 40' up in the air with a gantry around the outside. It was bloody freezing!
Did about 3 years on HT stuff upto 11kVa, Trawsffynned Power station was the biggest. We used to stand inside the stator core knocking the slot wedges in. Just over a year ago worked on a 7,400kW motor in a steel scrap merchants. That was a big bugger! On concrete pedastals about 40' up in the air with a gantry around the outside. It was bloody freezing!
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biggest I worked on 11kV, 14,600HP, drew 46,000A during start up Direct-on-line starting! non of yer star-delta noncy stuff.
Had 8 of them driving circ. fan impellors in nuclear reactors, fun to do air gaps using 2ft long feeler gauges..
motors had standard size doors at each end for access plus 12kW anti-condensation heaters in each motor.
ACB's to switch motor had individual arc chutes that needed crane to lift off for maintenance, nice warm indoor work though!
Had 8 of them driving circ. fan impellors in nuclear reactors, fun to do air gaps using 2ft long feeler gauges..
motors had standard size doors at each end for access plus 12kW anti-condensation heaters in each motor.
ACB's to switch motor had individual arc chutes that needed crane to lift off for maintenance, nice warm indoor work though!
Did some work on a site with a dedicated sub for a huge 100kW fire pump.
Huge cylinder of water kept pressuried by a small 20 odd kW pump. The water was drawn from an open reservoir filled from a river.
The sprinklers and fire hoses around the site where fed from this cylinder, all the sprinkler heads and the hoses under constant pressure from the cylinder. (sprinkler heads kept closed with glass vial, glass vial designed to fracture at certain temp).
The cylinder would provide enough pressure for a certain amount of time with x amount of ends open. The 100kW fire pump would fire up and run with the cylinder to maintain pressure. There was also an auto firing diesel pump which would take over should the mains fail and cylinder pressure drop.
This was on a site that manufactured cotton wool products - A huge fire risk. Weekly fires inside machines and ducts was not uncommon.
Site has gone now, the countries that supplied the raw cotton before bleaching etc ended up being able to supply the finished products (cotton budds, pads, tampons etc) cheaper than the factory here could purchase the raw materials. When the site closed down, many of the machines where sold to the competition abroad.
Huge cylinder of water kept pressuried by a small 20 odd kW pump. The water was drawn from an open reservoir filled from a river.
The sprinklers and fire hoses around the site where fed from this cylinder, all the sprinkler heads and the hoses under constant pressure from the cylinder. (sprinkler heads kept closed with glass vial, glass vial designed to fracture at certain temp).
The cylinder would provide enough pressure for a certain amount of time with x amount of ends open. The 100kW fire pump would fire up and run with the cylinder to maintain pressure. There was also an auto firing diesel pump which would take over should the mains fail and cylinder pressure drop.
This was on a site that manufactured cotton wool products - A huge fire risk. Weekly fires inside machines and ducts was not uncommon.
Site has gone now, the countries that supplied the raw cotton before bleaching etc ended up being able to supply the finished products (cotton budds, pads, tampons etc) cheaper than the factory here could purchase the raw materials. When the site closed down, many of the machines where sold to the competition abroad.
I've heard of these systems though never worked on one personally.
Did hear a story/rumour that the pumps should be run every 3 months or so to make sure the bearings hadn't siezed otherwise the whole system could be rendered useless if the pump failed to come on line if required.
We have a system which I introduced in work that once a month an apprentice has to go into the motor store and turn every motor at least 1¼ turns by hand but to ensure the shaft does not stop in the same position it was in before he turned it. This prevents 'flat' spots developing on the bearings and causing problems on installation.
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The process is sometimes called Bruneling - the weight of the shaft squeezes the lubricant out and this can cause flat spots on the bearings.
It is particularly acute if you also have vibration. This is why the spare bearings on a ship have to be turned at regular intervals.
It is particularly acute if you also have vibration. This is why the spare bearings on a ship have to be turned at regular intervals.
Well that should be easy enough - just ask your boss how much he is prepared to spend on wire and then buy the largest size you can get for that
I think you speak from experience and that answer is not as much as a jest as some might think -
I used to stand in regularly at a wholesalers and many folk used to get £5s worth of cable or £3 or £10 worth etc, it always amazed me they were going to add a point and it`s position was dependant upon the cost of the cable "Ha I`ll put an extra socket £5 away from an existing one".
The other "old Chestnut" was to ask for the correct size cable for sockets and you answer 2.5 T & E then the ask the price and then ask the price for 1mm - you know whats going to happen even if they deny it.
PS
Merry xmas everbody
Merry xmas everbody
interesting 'not-him-again' what you called Bruneling.
In power stations the main generator shafts going through generator and turbine can be over 50m long and for reasons stated by several people have a very high geared small 'Barring' motor to constantly turn shaft when not running at speed 1500/3000rpm .
In power stations the main generator shafts going through generator and turbine can be over 50m long and for reasons stated by several people have a very high geared small 'Barring' motor to constantly turn shaft when not running at speed 1500/3000rpm .
sparky123,
thats the reason in power stations they do it, mainly until cooled right down, then turn constantly at very low speed to prevent bending and 'stress reversals' due to weigth of shaft between bearings.
thats the reason in power stations they do it, mainly until cooled right down, then turn constantly at very low speed to prevent bending and 'stress reversals' due to weigth of shaft between bearings.
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