Puma / Dorman 6LE / MacFarlane B46B / 110 kVA Generator Resurrection

[awemawson]

An interesting concept that I'd not come across before John. I can see the theory but I'm not convinced I need it here.

I think I'd need a bit more than an RSComponents 1/4 watt carbon - what do you reckon 

[John Rudd]

Hmmm lemme see, 1/4 watt carbon? Err nope, I dont think it would cut it....

The  NER's we had with our gensets were housed in metal enclosures that were  quite large....in excess of a cubic metre, easy..and a seperate relay protection panel...

[awemawson]

From what I read, they are more applicable to REALLY large gen sets, not this tiddler of 110 kva

[Pete.]

Our towables are all earth-neutral bonded AFAIK. Not sure on the hired-in jobs but out 45/60/70/100's were all like that.

[PekkaNF]

Here regualtion requires one point earth/neutral. Simply put:
1: For tools etc. single consumer "machines" athe generator end is feeder and safety ground (etc.) there.
2: When generator is connected to residental emergency power or work distribution panel - that is point where all neutrals and grounds are connected.
3: No mix and match: Strictly forbitten to earth separately at generator end and distribution panel and connect with earth/neutral cable(s). Apparently too high risk for circulating currents and fault modes will multiply.

I am sure that there are many industry/trade/country spesific deviations that work remarkably well on those special circumstances. I have seen generators that have all wires brought from pable outlets into a box that has terminals to wire generator sagety ground to which ever combination to N/G outlet terminals - or disconnect them with links and this would give easy option for groung from either end.

[John Rudd]

As the forum has been down a few days, has any progress been made? 

Its a bit like the soaps, need the next episode....

[awemawson]

Well John, as you may imagine one or two things have been happening.

I've been working on enhancing the safety and security of the generator. Firstly fitting a lockable handle to the main cabinet to keep prying finger out, and also replacing the temporary knob on the inhibit switch with a key operated one.

The door seal got stripped out ready for replacement and the door given a coat of paint. I also decided to seal the base of the main cabinet with a sheet of zintec to keep the vermin out.

Then I've been making metal covers to cover up the various DIN rail terminals and wiring. They got a coat of paint this morning and hopefully can be fitted tomorrow.

Meanwhile it's developed two leaks. One to the flange of the oil / water cooler (leaking oil) and more worryingly  a water leak from my fabricated water jacket heater that resulted in it tripping my RCD!

Now I suspect that these leaks are inter-related - certainly both in close proximity. When I first tried the water jacket heater I had thought that it was getting rather hot and the heat wasn't being carried away as quickly as I'd have expected, and I suspected an airlock in the area.

I'll need to remove the right angled and gasketed flange that connects the oil / water cooler and remake the joints, and probably have another go at making a heater element, but that's for another day as it involves draining the coolant.

[awemawson]

Paint was nice and hard this morning so I fitted the safety covers to the Gathering DIN rail terminals and the controller and metering panel, so hopefully even the most determined fingers can't get into trouble.

Then I set to fitting the pair of angles that I'd fabricated and painted that will hold the poly-carbonate shield that will cover everything in the lower part of the control cabinet, and just have the rectangular bezel for the isolator protruding.

I had intended to bring the consumer unit forward 4" on spacers so that it's face was co-planar with the Isolator and cut another rectangle for access but in the end reasoned that access was fully possible by removing six screws, any tripped RCD's or MCB's would be visible through the poly-carbonate, and adding an extra stress riser to the poly-carbonate shield wasn't justified. I need to work out a scheme to cut a rectangle with rounded corners for the isolator to reduced stresses, having experienced polycarbonate stress cracking on my Beaver Partsmaster CNC Mill. The six mounting screws will be treated as I did on the Partsmaster, (*) with over sized smooth edge holes and 'top hat' inserts to take the screw clamping.

To help an awkward bit of layout for these angles I used a trick employed by the wooden boat builders and made up suitable 'length bars' to ensure things ended up in the right place - otherwise rather tricky 'in a box' !

Meanwhile the 3 1/2" BSP fittings have arrived for me to modify the exhaust layout, but that again is a job for another day.


(* https://madmodder.net/index.php/topic,9180.msg154826.html#msg154826 )

[John Rudd]

All coming together nicely...

Have you got your " Electricity at work act " signs in place?.....

[awemawson]

Work - who's working 

But I HAVE ordered the attached sign sized 300 x 400 mm for the door 

[modeng200023]

It is interesting that you are using inch measurements. I find that they are of a more useful size than centimetres. 

[awemawson]

I'm equally at home with either, but this enclosure was made to Imperial dimensions.

. . . it's horses for courses really - if I'm dividing something up into sections to (for instance) get equally spaced screws I'll measure it in both systems and use the one that works out most conveniently.

The box externally was made to be 36" so little point in using 914.4 mm !

[hermetic]

I agree Andrew, I use whatever measurement system is convenient too, but I do find it annoying that most metric dimensioned equipment never seems to be in round figures, I suppose that went out of the window with standardisation, or am I just a grumpy old bugger?

Phil

[PekkaNF]

fibonacci sequence
https://en.wikipedia.org/wiki/Fibonacci_number
+
Standard material sizes
+
Stock sizes
+
Modular sizes (often derived from archaic systems, like in building tradition)
+
Old standards and new standards
=
Part of the confusion
-> legacy system transfers from one system to another and related aproximations.

But people handle this usually pretty good.

[awemawson]

OK time to tackle the oil drip and water leak. Not been looking forward to this as the mounting bolts on the 90 degree adaptor on the rear of the oil / water heat exchanger are mutually blocking access to each other.

First job, drain the coolant below the heater exchanger level, saving it as it has anti-freeze that I recently added. No suitable containers so a friend produced a 205 litre plastic drum that had previously held cow teat wash (!) After a good clean out, coolant transferred to drum and I could start dismantling. I removed the electrical connections to the water jacket heater, and unscrewed it - it was evident that my braze of the copper slug to brass fitting had not been perfect and coolant had got into the rear of the heating element, hence tripping my RCD. I will make another out of solid bronze, so hopefully no leaks as no joints! The element is powered up as I type on a 24 volt lab supply (so 20 watts not the rated 200 watts at 240v) drying out - so far leakage has reduced from 120K to 6 meg-ohms but I'll let it cook for a while.

Then I started on the bolts - fiddly but just possible and eventually they were all out. The right angled piece was firmly stuck on the one locating stud (all the rest were bolts) and I gently applied the thin end of the wedge in the form initially of a putty knife taking care not to damage the flange faces. To get further spacing I ended up using two putty knives with a screwdriver blade between them again to avoid sealing face damage.

Eventually she was off, with the expected deluge of residual oil and water - turns out that the heat exchanger body has a large 'O' ring sealing it to the housing, with gaskets to engine block and main casting. I very much doubt whether the parts are available, and indeed the parts book says that the O ring is supplied as part of the tube assembly. I will ring around on Monday, but the gaskets are relatively easy to make, and the O ring will be available if I can accurately determine what size it should be. It slides into and seals in a  90.75 bore so probably needs to be a tad larger than that.

I strongly suspect that I caused all this havoc When I installed the water jacket heater it got rather hot and I suspect cooked the O ring due to an airlock. I now realise that there is a drain plug below it where water / air can be bled off.

[awemawson]

A little more investigation on the "O Ring Seal" leads me to believe it probably wasn't originally an O ring, as the cross section is rather rectangular. But this may be due to age (1972 remember) and over heating.

The groove that it sits in is 4.14 mm wide, has a minor diameter of 84.46 mm and the bore that it seals in is 90.75 - not many standards there !!

So if it had a 3 mm cord O ring 2 x 3.00 plus 84.46 gives 90.46 o/d - too small to seal

If it had a 4 mm cord O ring 2 x 4.00 plus 84.46 gives 92.46 o/d and probably too big to enter the bore

If it had 1/8" cord (3.18 mm) 2 x 3.18 plus 84.46 gives 90.82 which is a possibility though slightly on the small size

I'll try and get the real thing, but I've ordered a 4 mm cord 83 mm O ring reasoning if it is stretched to fit the groove it's cord diameter will shrink a bit ad it may fit - after all it just needs to go n once, it's not a rotating or constantly sliding fit.

Meanwhile I've drawn up the two gaskets needed and cut them on the laser cutter. Samples are gasket material but to ones I use will be a bit thicker - this are just 'trial fits' to prove the drawings.

[John Rudd]

Those gaskets look the bizz.....


You could have a little sideline in gasket supply.....

[awemawson]

Yes I was rather pleased how they came out, and only took 20 minutes.

A quick draw in Autocad, having measured up, learnt how to place '3 point arcs'  and 'Tangent Snap' for the sides of the four hole gasket, then export as .DXF's to RDWorks which is the laser driver and bobs your Uncle 

[PekkaNF]

Nice gasket!

Does that heater mounts onto oil/water heat exhanger? That would be nifty place to heat both oil and water.

Pekka

[awemawson]

Yes it points forwards toward the tube pack and is immersed in the water.

[awemawson]

Time is pressing this morning as we have a luncheon appointment, but I'd intended to cut the hexagon on my bronze stock to re-make the heater unit as an integral (no joints) piece.

Sadly my bronze bar proved just too small so I've ordered a short length of  35 mm brass  hex to make one later. However I thought that I'd have a go at re-making the first one I made - I'd thought I'd run out of silver solder and used silphos instead however a recent rummage has revealed another stash of various silver solders at differing melting points 

So the plan of attack was to clean up the inside of the joint between the copper slug and the brass fitting and run a fillet of silver solder around it. First attempt didn't fully wet, but a re-clean in the grit blaster and re-flux cured that.

To inspect the joint properly I then again grit blasted it, and although it looks sound I decided to subject it to a 'bubble test' at 100 PSI. Cobbling various plumbing fittings together to adapt it to my airline I dunked it in a bowl of warm water and looked for escaping air. None apparent so I 'think' it is now sound.

[PekkaNF]

Heaters are a little picky that way. When they are subject to changing temperature gradients parts tend to find weak spots.

[awemawson]

No joy sourcing the correct heat exchanger sealing ring - parts book calls it an O ring (#576/35) but it has a rectangular cross section.

Simply Bearings delivered a pack of 4 mm x 83 mm and 4 mm x 84 mm normal O rings so I could try different fits. The original created a seal that very easily (too easily) could be pressed home. I tried the 4 x 84 first with copious amounts of Vaseline and careful pre-cleaning of the groove and taper on the adaptor. No way would it just press on, but pulling it on with it's mounting bolts it went home when I did a trial assembly. This let me pull it apart again and examine the O ring for damage, as possibly it could have had it's crown cut off.  No visible damage so I decided to go with this size of O ring.

Out with the Blue Hylomar sealant, a light smearing on both sides of the gaskets then it was just a case of bolting it together - except for those bolts that are  at 90 degrees to each other and clash. To get the engine side gasket aligned I had first to put it's bolts in, loosely tighten two of the ones around the O ring, remove the engine side bolts, put in the other two round the O ring, pull them up reasonably tight, put back the engine side bolts and rinse and repeat. All this fussing as of course as the O ring housing is drawn together, the alignment of the engine side bolts changes as the flange is drawn down the side of the engine ! Got there in the end.

Can't test it until I've sorted out the water jacket heater.

[awemawson]

This afternoon I had a bit of time to start on the exhaust modifications.

First I plasma cut a flange with a 65 mm hole from 12 mm plate - first time I've cut as thick as that on the table. First attempt failed - lack of penetration (which wiped out a set of consumables) so for the second attempt I cut the tracking speed in half to be on the safe side, and all was well.

Then set it up in the 4 jaw chuck for boring and threading. "Take a 72.8 mm drill . . . " well obviously I bored it and threaded it to be a tight fit half way up a 2 1/2"  male BSPT fitting.

All seems to screw together but I've still not finalised how the exhaust will run. It will be easier to get ideas when I have bits to screw together !

[awemawson]

An exhausting morning - literally 

Objective: to try and reduce the existing exhaust system to its component parts.

a/ Original exhaust flange is welded to a length of flexible pipe which is welded to a pipe stub, so that's not unscrewing

b/ Tail Pipe is welded to a socket fitting which is screwed onto the silencer - that unscrewed with heat and much effort

c/ Pipe stub on flexi screws into elbow on silencer - that again unscrewed with heat and a lot of puffing and blowing

d/ Elbow screws onto pipe stub on silencer - this has so far resisted all efforts to unscrew it. I've had it glowing red (oxy-acetylene torch)  - I've shock cooled it with water, and tried several times but . . it want's to stay where it is

Never mind, I can still try a few layouts, and accept the limitation that it has an immovable elbow ! Without being able to unscrew the elbow, a drain plug in the silencer cannot be rotated to a functional position.

First vertical - probably  simplest but I don't have the height where the generator is going

Secondly folding backwards then a 180 return to bring the tail pipe pointing forwards again. I prefer this lay out.

Either layout needs a short flexi from exhaust flange to pipe to avoid cracking the manifold, and #2 will need a heat shield to stop radiated heat downwards. Both will need some sort of support framework making with the silencer mounted on rubber suspension.

. . as usual all suggestions welcome