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

[awemawson]

Time will tell Russell, but I think so - the whole header tank gets all hot and bothered as soon as the inbuilt thermostat opens, as the engine holds a large volume of water which of course rushes there quite quickly. I expect that there will be some lag, and also the hysteresis in the system should prevent it flapping open and shut all the time.

. . . but if it's not quite right I'll (try and!) sort it !

The other thing I need to sort out before I nail the lid on is arc suppression on the relay contacts. As the  actuator is reversed by reversing it's polarity I cannot just put a quenching diode across it. So I suppose either a capacitor / resistor network across each contact pair (a pain physically) or maybe an MOV or varistor across the actuator itself

As usual, all suggestions welcome !

[WeldingRod]

Are R/C type suppresor?

Sent from my SAMSUNG-SM-G891A using Tapatalk

[awemawson]

For a coil that is driven in only one polarity usually it suffices to put a (flywheel) diode across it in the reverse (ie non conducting) direction, so that as the relay contact opens the back emf of the coil is shorted.

In this situation, this simple solution is not applicable as the coil can be driven in both polarities.
Back to back zener diodes, an MOV or Varistor, or a simple capacitor in series with a low value resistor are possibilities.

I think an MOV is the simplest but without robbing other equipment, I have non to experiment with !

[PekkaNF]

You prpbably know that MOV:s will take only limited amout of hit and then fail and short. You need a some sort of fuse on feeding line or limit the current safe way - unless it is intrinsically safe.

Then again RC surpressor will fail eventually too. But I have used to see them in industry often on AC solenoid valves.

This sort of thing is found to operate well. I think that since this is AC/DC this sot of stuff would work in switched polarity and would be a standard item.
https://www.productsforautomation.com/murr-din-43650-formb-24V-mov-11021-p/7000-11021-2260150.htm

Do you like that sort of component?

Alternatively:

If I had to build one, I would resort to ovekill it: I would put RC-snubber and the higher voltage MOV with series PTC-fuse tied to MOV.
https://m.littelfuse.com/~/media/electronics/application_notes/reed_switches/littelfuse_magnetic_sensors_and_reed_switches_inductive_load_arc_suppression_application_note.pdf.pdf

You know the standard rouge: MOV+PTC in series, but mechanically tied together with hitemp shrink tube or in same encapsulation (2-4 lead models).
https://www.automotive-fuses.com/sale-11081692-thermal-protection-surge-suppressor-metal-voltage-dependent-resistor-mov-tmov25s-series.html


Pekka

[mc]

What about a couple Zener diodes in series back to back?

However, I probably wouldn't be that concerned about arc suppression. I'm guessing most of those components will be rated for a good few amps at 240VAC, in which case a couple amps at 24VDC shouldn't be a major concern.
If it was, I'd design the circuit so a couple pluggable relays were doing the actuator switching, so you could just change the relays if it did become an issue, however you're then into the possible area of the switch contacts oxidising due to lack of switching current.

[awemawson]

Morray, the switching (of 3.5 amps @ 24v DC) is done by a single four pole change over plug in relay, and as it happens I have about thirty spares in hand as they are the style that the original generator controller used, so that is one approach that I seriously considered.

But seeing the not inconsiderable arc leads me to want to tame it !

(The back to back zener method is one of the  options I cited a couple of postings above)

At the moment getting 'all the bits' into that box and connecting them is proving quite a challenge despite having installed pre-wired sockets and plugs for all external connections.

[awemawson]

This control box for the shutter automation has taken far too long for such a simple device, and it's driven me up the wall!

The real problem is I've been too ambitious getting it into a small box, with the result that virtually none of the switch or relay contact screws are accessible with the components in the box. This means that wiring has had to be done as a 3D jumble on the bench, and the bits then returned to the box - this necessitates wires that are long enough to manoeuvre the  items as they are re-fitted. Not too bad if the circuit was finalised and I only had to do it once, but that wasn't the case !

However, a mile stone today, all is assembled in the box, and now the box has plugs and sockets for all it's external connections so fitting to the generator 'should' be trivial (famous last words!)

I was extremely fortunate that the holes that I'd bored for cable glands exactly matched the sockets that I then decided to use, so that was a bonus.

I've made up cable forms to run to the thermostat and limit switches and hope tomorrow to get it actually in operation.

(Attached is the final version of the circuit)

[awemawson]

So as I'd hoped, I managed to fit the control box this morning. I need to finalise the cable runs, and also where I source the 24 volts from. Ideally it would be via the key switch on the Deep Sea 3110 control panel, but that doesn't have the current capacity.

Anyway it's is at last fundamentally working as intened - just awaiting titivation.

[awemawson]

So now I need to sort out how to get fuel into the tank. There is a filler but it's rather high up to pour into.

Originally there was a semi-rotary hand pump fixed to the tank support framework, but it's 'gone missing' over time. Mounting holes measured at five inches spacing but I couldn't for the life of me find one that size either new or used.

Several of varying sizes appeared on ebay while I was looking and eventually I bought the nearest to five inches that I could (measuring and scaling pictures!) for the princely sum of £12. This turned out (I think!) to be a bargain - it's mounting holes are 5 1/2" apart but looking at the pipe mounts they have original over spray paint, and there is still a membrane across the opening, so I presume that it must be 'new old stock'

I'd intended to CNC plasma cut a new mounting plate, but removing the old one for measurement realised that it could be adapted if I could manage to mount a 'false centre' in the old spigot hole and bore it out larger and offset 1/4" .To this end I bolted a strip of steel across the old hole, drilled a centre in the new location and cut it out with a hole saw - all went well with no dramas 

I still need to make a wooden handle for it and sort out it's plumbing - input and output are both 1" BSP, the tank input orifice is 1/2" BSP, and I think I'll put a ball valve below the pump to try and minimise drips after use - but that's for another day - at least the pump is now off my bench 

[mattinker]

Andrew,
Coming along nicely, looking forward to seeing all this in person!

Matthew

[awemawson]

This morning I managed to fit the upper diesel plumbing from the pump to the tank using what I had to hand. Time was when I had loads of gas barrel, but that vertical bit (which needed extending two inches) was what was originally on the machine when it came, and despite searching high and low I couldn't find a longer bit. The plumbing 'odds and sods' box provided the solution.

The original pump must have been an odd (taller) shape, and of course this one is 'side stepped' half an inch being wider.

Of course I don't actually know if this one works, nor for certain which way up it's supposed to mount - I put it with the cast in model number letters upright so it's probably right 

Bushing and ball valve on order for the lower pipe that will go to a Jerry Can.

It was too darn cold this morning to do any more with the shutter controller wiring, so I came in, lit a log fire and chatted with the dogs 

[PekkaNF]

You know - I saw this most peculiar thing one day: One man was talking to a cat!

I returned home, told what I had seen to border collie and we both had a good laugh.

[awemawson]

So I braved the minus 3 degrees Centigrade this morning and finished off the shutter controller wiring. Amazingly I was able to pull a 0V return cable through the existing convoluted conduit that snakes from the alternator, across the front of the engine and up to the ammeter panel - surprising as it already has quite a bit in it - I used a nylon conduit pull cable  which managed to traverse the not inconsiderable bends.

This allowed me to source the 24 volt feed to the controller from the ammeter panel, for which I ran another length of 20 mm convoluted conduit.

I'm amazed how well this Dorman diesel engine starts in cold weather - very impressive 

[russ57]

And if you get that induction furnace connected and loaded up, you might raise the temperature a bit....

Russ

[John Rudd]

Does the engine have any glo plugs to aid cold start?

[awemawson]

No John, it just relies on squashing that diesel vapour. There is of course the water jacket heater that I could use but at the moment it's off and the engine still fires up on the first cranking - possibly slightly more black smoke than on a warmer day but it's marginal.

[John Rudd]

There's always Eazi-start....

[AdeV]

There's always Eazi-start....

I always preferred the Australian name for that stuff: "Start ya bastard!" 

[mattinker]

If it starts, it doesn't need anything ! Definitely no easy start!!

[awemawson]

Easy start always has to be an absolute last resort. It can do all sorts of damage to the piston lands above the top ring, breaking them.

As for the Dorman, there really doesn’t seem any need at all 

( I have used Easystart to reseat tyre beads, in fact come to think about it it was on my last big generator, an Agrecko that I used for the Induction Furnace)

[philf]

There's always Eazi-start....

Always worked well in my air rifle!

[Sea.dog]

IT appears there's a 750 kVA genset going in Harlow, Andrew 

https://www.facebook.com/marketplace/item/585598342202648/

[awemawson]

Seadog, put it on a pallet and send it over 

Looks to have a nice Paxman Diesel engine, I bet that sounds lovely.

As for mine, I’ve been distracted this past week sorting winter fuel, which involved totally reorganizing the tractor shed to extract my 17 foot Ifor Williams trailer (blocked in by many things including the generator), and collecting 3 1/2 tons of oak cord wood from a friends wood, logging and splitting it. (Anyone want 4 wheelbarrow loads of sawdust!) today’s job is to put everything back so I can get on sorting the generators exhaust. BTW this is next years fuel not this year.

[Sea.dog]

I'll see what I can do 

I'd have thought that with so much sawdust you'd be thinking along the lines of manufacturing your own pellets and having a biomass burner 

[pycoed]

<which involved totally reorganizing the tractor shed to extract my 17 foot Ifor Williams trailer>

Need a bigger shed! - just proves the impossibility of building a shed large enough to last more then a year of "collecting"