Does anyone know what this could be off?

[normspanners]

I used to work at the BBC and the transmitters had their own generators. When they knew there was a power cut coming they used to bring the generators up, get them in sync with the mains and then connect them in

The story was that one day they weren't in sync when they dropped in and a piston ripped itself out of the engine, out through the building wall and off down the hillside, probably something similar in size to that

When 2 or more gennies are locked in phase, if one gets a fault or runs out of fuel etc the others will keep the dead one turning. at the same speed.

 

[penfold]

Only if there isn't a proper set of breakers with reverse current detection; even the 30 year old setup on our boat has that.

 

[MoreWellie]

even the 30 year old setup on our boat has that

I think the incident happened around 50 or more years ago, I only mentioned it as an example of the sorts of forces involved in large (to me) generators/engines and what happens when things go wrong

I could have used a hydrauliced land rover engine as an example as that had twisted con rods and holes in both sides of the engine but I didn't think it really compared scale wise

 

[penfold]

Theoretically modern generator breakers with features like reverse current, high/low freq, high/low voltage protection should also protect against being closed when sources are out of phase, but I wouldn't like to be around to find out. Pistons leaving via the crankcase seems mild by the standard of some of things I've read about; the instantaneous torque that can be exerted snaps crankshafts, rip rotors apart and tear generators from their mounts and send them across machinery spaces at speed.

 

[addjunkie]

Every machine has a failure mode somewhere. Ships engines are no worse than others.....personally i still find a big two stroke interesting, cant be doing with all this diesel electric malarky running on gas etc

 

[penfold]

I'm still crossing my fingers the yanks will come up with an atomic kettle that's cheap enough for merchant shipping before I draw a pension, I still want a steam ticket! Not much chance of it emerging commercially but the Pentagon have an operational need for a frigate-sized power plant and the budget to develop one(barring the unlikelihood of fusion or dilithium crystals), and if they don't do it the Chinese probably will.

 

[addjunkie]

I'm still crossing my fingers the yanks will come up with an atomic kettle that's cheap enough for merchant shipping before I draw a pension, I still want a steam ticket! Not much chance of it emerging commercially but the Pentagon have an operational need for a frigate-sized power plant and the budget to develop one(barring the unlikelihood of fusion or dilithium crystals), and if they don't do it the Chinese probably will.

Ah the age of steam, many years ago back in the early 80s i was a cadet. Sailing on a coaster. We were in blyth, i wanted across the river and got a lift on an old steam recip collier crossing to load, was very interesting. Think its now in liverpool maritime meusem. i never did any steam time, as for my tickets they are now so expired, im not even sure where they are!

 

[Tinbasherdan]

Bit smaller but I read an old article by a ex navy torpedo boat crew. They were fitted with 3 off Packard merlins, which were spun up by a ford v8 donkey engine on a dog clutch,spin the v8 up, bang the clutch, merlin fired and clutch self releases. Apparently the clutch didn't engage and the merlin over revved the v8 and spat it's heads through the deck. Ouch!

 

[Wedg1e]

When 2 or more gennies are locked in phase, if one gets a fault or runs out of fuel etc the others will keep the dead one turning. at the same speed.

I remember talking to an old boy a good while back who'd worked in power stations when each station served an area of the country, there was no 'national grid'.
Apparently the engineers had figured out that if you could run two alternators to very close speeds/phases, if you connected them together they'd self-synch and share the load... but the powers that be wouldn't let them try it as their tame physicists said it wouldn't work.
The story went that cables were laid, switchgear was installed and late one night, bank holiday weekend on Xmas day or whatever, a pair of oscilloscopes were connected to each power station and at the appropriate moment a switch was thrown - and it all worked, and has done ever since.
So that was Great Britain. Now what happens...?

 

[normspanners]

The story went that cables were laid, switchgear was installed and late one night, bank holiday weekend on Xmas day or whatever, a pair of oscilloscopes were connected to each power station and at the appropriate moment a switch was thrown - and it all worked, and has done ever since.

A light bulb is all that is required to sync similar gennies , but three is better incase of a filament blowing. Using the one dim method.
my mate has an old 30 kva 3phase lister he uses for heavy 3ph work, and back feeding the house when the power goes he had an issue one day when something went wrong with the switchgear at the exact moment the mains came on and he said he hadnt realised appart from he thought he heard a little grunt from the lister, that the power was back on, until he came to shut down the genny and she wouldnt stop! He was soooo lucky everything must have been VERY close to sync when it connected.

Bit smaller but I read an old article by a ex navy torpedo boat crew. They were fitted with 3 off Packard merlins,

THANK YOU DAN!!! I was allways obsessed with MTB'S
That has brought back an awsome memory of being on the norfolk broads with mum n dad and we where moored up on one of the wideish river that led out to sea ( somewhere ) we where up a little side cutting happy having tea when I could hear this noise getting louder and louder and being a petrol head even then I was out looking for whatever it was. WELL around the corner down stream from us came an old private converted to cruiser MTB with its spotlights on, it rounded the bend banked over like a motorbike its engines where screaming must have been close to flat out ,well it sounded F KIN AWESOME, he spotted our lights and throttled back probably a bad thing to do coz it dropped back in the water and filled the river !! the wash off it was going over the banks and our 40ft'er nearly ended up on top of the bank, food went every where and the dishes where smashed the moorings were ripped out etc mum wasnt pleased but dad n I thought it was ACE . Not sure about the legallity of his actions but man it was GREAT that noise was fantastic. 3600 hp and 40 knotts !!! but the fuel consumption !!!!!

it looked a little like this

 

[Tinbasherdan]

Would probably be an old vosper. Beautiful boats, me and Mrs dan considered buying one that had been converted into a houseboat for a while, although she'd lost her merlins and gained 3 Perkins instead if I can find a decent hull drawing of one I'm thinking about making a large scale Ali hull model of one

 

[normspanners]

Would probably be an old vosper. Beautiful boats, me and Mrs dan considered buying one that had been converted into a houseboat for a while, although she'd lost her merlins and gained 3 Perkins instead if I can find a decent hull drawing of one I'm thinking about making a large scale Ali hull model of one

Not sure what it was it was probably 50 ish yrs ago!! and dont forget it was in view for only seconds but those seconds were fantastic most of the boat was out of the water when I first saw it and she was decked over at about 12-15 degs!! it appeared to empty the river first then came the wash, it formed its own little tsunami !!
For a young petrol head the sight was incredible!

although she'd lost her merlins and gained 3 Perkins instead

just found this;

When it was powered by triple merlins it was rated at 148 GPH....

no wonder the merlins where taken out !! 666 ltrs an hr or today =£832 an hour

just worked out if it was 30 secs I saw it, it would have cost today £7

 

[colnerov]

Hi, A mates late father served on MTBs during the war. They did dangerous missions in dangerous boats (no armour) they relied on their speed. Apparently they were called "Iron men in wooden boats"

Colin

 

[Wedg1e]

I was working in Pompey about a decade ago and spotted what looked like a torpedo boat, minus torpedos, alongside Gunwharf Quays.
After a bit of digging it proved to be Brave Challenger (launched as Merlin), built by Vospers on a patrol boat hull as a private yacht for some foreign millionaire.
Triple Proteus gas turbines knocking out 20,000 SHP if I recall rightly; apparently she was clocked crossing the Channel at 60 knots in the 1960s!

 

[Wedg1e]

A light bulb is all that is required to sync similar gennies , but three is better incase of a filament blowing. Using the one dim method.

How does that work then? Phases cancelling out or summat?

 

[Tinbasherdan]

I was working in Pompey about a decade ago and spotted what looked like a torpedo boat, minus torpedos, alongside Gunwharf Quays.
After a bit of digging it proved to be Brave Challenger (launched as Merlin), built by Vospers on a patrol boat hull as a private yacht for some foreign millionaire.
Triple Proteus gas turbines knocking out 20,000 SHP if I recall rightly; apparently she was clocked crossing the Channel at 60 knots in the 1960s!

Can well believe it. We had 3 offshore patrol vessels built for the Middle East by BAe and then turned down by the buyer -long story- moored up in the docks. There was a skeleton crew on board to keep them running until a buyer was found and occasionally they took them out for a run. We could manage about 25-30kts on the pilot boat and when these things opened the taps they'd pull away like we were stood still

 

[normspanners]

How does that work then? Phases cancelling out or summat?

Yes easier to watch

some people use bulb one in phase two out of phase so you switch on when two are brightest and one out.

 

[gordon stephenson]

Very good illustration Norm, Enjoyed watching it and am a little bit wiser, thanks,

 

[normspanners]

I was working in Pompey about a decade ago and spotted what looked like a torpedo boat, minus torpedos, alongside Gunwharf Quays.
After a bit of digging it proved to be Brave Challenger (launched as Merlin), built by Vospers on a patrol boat hull as a private yacht for some foreign millionaire.
Triple Proteus gas turbines knocking out 20,000 SHP if I recall rightly; apparently she was clocked crossing the Channel at 60 knots in the 1960s!

A bit of old chat I found

http://www.ybw.com/forums/showthread.php?2845-What-type-of-drive-on-Brave-Challenger

 

[normspanners]

Every machine has a failure mode somewhere. Ships engines are no worse than others.....personally i still find a big two stroke interesting, cant be doing with all this diesel electric malarky running on gas etc

I had a 500 /600 kva genny driven by a big boat engine 8 cyl IIRC, it had only done something like 100hrs, it was a standby from B/Aero we ran it for a while but a piston went, I think it was the rings had seized due to standing for too long. One piston cost much much more than we paid for it !!

Not sure on this but I think there is some kind of law that if you have a genny over a certain size it HAS to connected to the National grid.