Lister Engine Forum

How to / DIY => Generators => Topic started by: Adscnc on August 15, 2021, 03:37:27 PM

Title: Lister HA and Brush RS1B generator
Post by: Adscnc on August 15, 2021, 03:37:27 PM
Hi
I have just acquired a Lister HA 2 cylinder with a Brush RS1B alternator generator.
(3 phase 15 Kva)  it hasnít run for 10 years.
The engine started on the button.
At this stage I didnít know wether it was capable of generating any electricity.
I fired it up and all went well, until after about 90 seconds I could smell that familiar smell of burning electrics so I shut her down.

It appears that the fins have over heated and taken out a cable and melted the connected block. See photos.
Only the 2 right hand front fin sets have over heated.

Some questions:

What are the fins for? Is it the rectifier/ voltage regulator?
Why might they have over heated, a short some where?
I guess it is not worth repairing.

Can I fit a  modern voltage regulator?
Should I consider replacing the whole alternator?
The lister engine runs well, no oil leaks and in great condition, spins a 1500 rpm.

Is this suitable?
https://www.ebay.co.uk/itm/New-15KVA-400V-1500-Rpm-Stamford-UK-Diesel-Generator-Alternator-450-vat-/254634455766?mkcid=16&mkevt=1&_trksid=p2349624.m46890.l49286&mkrid=710-127635-2958-0
I appreciate that there is some engineering required to mount it!

Any thoughts on this would be appreciated.
Thanks
Title: Re: Lister HA and Brush RS1B generator
Post by: mike90045 on August 16, 2021, 07:27:34 AM
Those fined parts are Selenium Rectifiers.   When they die, they release toxic fumes.  Your manual/schematic will give the voltage and amp rating, modern replacement diodes are much smaller

The cable likely was hanging by a just few strands which were overloaded and melted the terminal block. ( IMHO )
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 16, 2021, 07:03:33 PM
Hi All,

I have researched fitting a solid state rectifier and looks very possible. Unfortunately I dont have a manual , the only info i have is what is on the plates.

Can I fit an AVR? if so does this do away we the need for the rectifier?

Thanks
Title: Re: Lister HA and Brush RS1B generator
Post by: mike90045 on August 16, 2021, 07:27:36 PM
What  is the info on the plates ?    300V  5A ?  something like that ?

You still need to rectify to get the DC control voltages to run the DC half.

I don't know anything about retrofitting a AVR to those.
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 16, 2021, 07:57:56 PM
 hi
415/230 volts
20.9 amps
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 17, 2021, 12:19:32 AM
it looks to me like a transformer controlled generator, the three large coils above
the selenium rectifiers sure make that case to me, however can you provide a picture of the whole back end, to include the rest of those coils?

the 415v also makes me think of 3 phase, i have an stc 12 that is three phase and has 415volt output.

if it is a transformer controlled generator, i don't believe you will be able to use an avr
 and buy the looks of the windings in the picture the enamel is looking to be in pretty questionable condition.

having said all that, transformer controlled generators are pretty interesting animals capable of much heavy motor starting loads that avr controlled generators, often having surge rating 2x that or the rated load for something like 3 seconds or maybe more.  they can be very tough and hard to kill.

you can replace the selenium rectifiers with silicon rectifiers, but the voltage drop is much less for the silicon rectifiers so the field current will be higher.  there probably is some sort of adjustable field resistor (wire wound affair with a screw terminal that you can adjust).

if you can find a manual or other info on the generator head, i would recommend checking out what you have before you opt to scrap it for a replacement head.

fwiw
bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 17, 2021, 08:40:21 AM
Many thanks Bob.
Good news I have found the manual for it online at ďinternal fireĒ
My wiring is exactly as page 4.
I note that you can fine tune the output by choosing different tappings from the transformers.
So my first task is to choose a solid state rectifier and wire that in. I need a bit of help here choosing the right one and working out which connections to use?
I also need to replace the suppression capacitors that run off the slip rings.
You mention that the enamel is not great, what exactly do you mean, what are the consequences?
Iím enjoying the learning curve on this project!
Regards
Alan
Title: Re: Lister HA and Brush RS1B generator
Post by: oldgoat on August 17, 2021, 12:11:27 PM
You can pick a 3 phase 1000v  50 amp bridge with heatsink from ebay for about $20.00 as I assume the dc goes to the X and X1 terminals.  If not it will be 6 1000v 20 amp diodes again off ebay.
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 17, 2021, 12:37:23 PM
Thanks Oldgoat.
You have confused me a little there.
Youíve listed 2 different items. Do I need both?
Could you explain a little further?
Thanks
Al
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 17, 2021, 02:08:47 PM
what i was in reference to in relation to the windings enamel, is the insulating coating
that appears to have some cracking and corrosion in the pictures, it might be just an artifact of the photo and not as bad or bad at all as it looks in the photos

in any case, i would carefully inspect those windings, and get a small can of glyptal (sp) or its equivalent and brush some on the windings to help seal them up and secure them if any are loose so they don't grind on one another from normal vibration and short.

i think the stuff is called glyptal, whatever it is, check with a motor rewind shop and they can tell you what to use, for that matter take a small jar with a tight fitting lid and see if they will sell you a small quantity.

you mention finding a manual, do you have a link to it?

many years ago we discussed either here or on the microcogen forum the transformer controlled generators, and at the time i found a link to the ST generators that are transformer controlled, but have never seen or hear of one being imported to north america, at least one that ended up in the hands of a forum member.

if that is what you have, and i suspect it is, i think you will be really happy with it once you get it sorted out.

if it were mine i would try to get it working to determine if the thing wasn't internally damaged in some way, such as shorted stator or rotor, and if it checked out ok, i might well take it all apart and replace the bearings and do a thorough cleaning, and may well also send the stator and rotor out to have them vacuum dipped and baked if it looked like the insulation was showing signs that it might be improved upon.

all in all a really nice generator design.

bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 17, 2021, 04:08:35 PM
Hi Bob

Here is the link to the manual.

https://drive.google.com/file/d/1BBu5Z5CbzI7XI0-5yLBqb94Zl7q1BJqm/view?usp=sharing

its a good manual and has answered a few of my questions.
my wiring is exactly the same as page 4.
Regards
Al
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 17, 2021, 04:18:21 PM

When adding the bridge rectifier how do work out which wires from the stator are + and - ?

Al
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 17, 2021, 05:36:50 PM
on page 4

lower part of the schematic shows the rectifier bridge (selenium rectifiers) that you will be replacing, the three phase coming down off the transformers to the rectifier makes no difference so long as you follow the layout as illustrated, no need to worry about which wires go to which set of diodes

the output that goes to the right of the schematic to X and XX and then up to the field will be the rectified DC coming off the rectifier bridge, and again it will make no difference which is which, unless one lead is attached to a ground before it gets to the field, but the schematic does not show that, and i would be surprised if a ground connection was made.

i didn't read to far ahead, but yes this is a transformer controlled generator, and of particular note, the field is fix (it is mounted to the outside of the case) and the armature is where the power is taken off off, via the slip rings.  this design is much like the old winco design typical of what was sold here in the states for decades, and for that matter may still be offered.

taking power off the brushes requires a relatively large set of brushes, but in my experience the design is about as tough as a tank!  they just seem to work and work and work forever.

if you read the voltage adjustment, you will see the part about changing taps on the transformer and also if still out of range changing the transformer air gap.

i think you will be probably having to not only change taps, but likely the air gap as the silicon diodes (rectifier bridge or discrete units)  have a much lower voltage drop than do selenium rectifiers.  so with lower voltage drop you will likely have 20-30 volts higher output than you probably would like?  i assume 230-240vac 50hz for your use?

what is interesting about the design (transformer control) is the field is supplied with a current for normal output (taps) and if you have a heavy load to have to start the transformer have higher current running through them which boosts the output to cover the droop.  set up correctly they work very well and are capable as stated before of starting heavy inductive loads on the order of 2x or more for a few to several seconds.

so if that unit is rated for instance 10kva it probably can provide 20kva for several seconds without breaking a sweat... it will be limited by the power available from the engine.

i think you have  cool unit, well worth working out the problems and getting it back up and running again.

bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 17, 2021, 05:39:46 PM
did a little more reading and found that X terminal to the field they call for it being connected to the + (positive) connection of the rectifier bridge output, and XX being the - (negative) connection to the field.

even though it really shouldn't matter, i would follow their dictates

edit
further reading i find that the field should be about 10% of the output under load. this is a nice spec, so for a 230vac output, i guess they are looking for approx 23vdc on the field.... that will give you and idea how far off the field voltage will be with the new rectifiers, i would expect you might see 25-30vdc? 

the manual is actually very good, and has more detail that i have found before for transformer controlled generators, and having the theory of operation illustrates how they work.

bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 17, 2021, 06:24:46 PM
Thanks Bob
Will digest this and hopefully make some progress.
Iíll update the post as I progress.

Al
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 17, 2021, 06:40:05 PM
Hi Bob
Any thoughts on fig3 page 5, using a variable ratio transformer to adjust the voltage?
Al
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 17, 2021, 09:09:12 PM
i think you can use the variable transformer, but you might find it doesn't provide enough range to get you dialed in to the voltage you are wanting.

whatever the case, i am sure it can be tailored to get to where you want it to be.

just follow the steps outlined in the manual and you will be golden.

bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 23, 2021, 10:27:26 AM
Hi Bob
Have tidied up the wiring and fitted bridge rectifier.
When run i only get 16.35 volts on all 3 phases at the head.
I have flashed the stator field with 24 dc. Done this twice now in accordance with manual.
Engine running at a constant 1570 rpm.
Any pointers as to where the problem may be?
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 23, 2021, 02:23:19 PM
take a good look at the slip rings, they should be a bright brassy color
if they are dark, chocolate color, or greenish they need to be cleaned

you can use some 400 wet or dry paper, and scrub them up to brighten them
and then turn the paper over and use the slip rings to provide the profile to give the brushes a bit of scrubbing too.

very typical of slip rings that have been sitting around not used to get a bit oxidized and this makes for a great insulator or in your case a pretty good insulator

also check what the voltage is coming off your rectifiers, going to the field coils.

can you measure the voltage at "x" and "xx" while running?

also check all connections, everywhere that you can get to.

another thought would be to check the field coil continuity, removed either "x" or "xx" from its terminal and then check the resistance across the field wires that attach to "x" and "xx", you only need to remove one leg.

i have no idea what the resistance should be, but i would think maybe somewhere from a few 10's of ohms, to maybe a hundred?  what i would not want to see is an open circuit, which would lean toward either a burned out field coil or a broken lead between coils, or lead going from "x" or "xx" to the coils.

the schematic doesn't show anything between the x connections and the fields, so not much to go wrong there, but an open wire, or bad connection, worse an open field coil.

if it turns out to be an open field coil, don't fret too much, it is much easier to replace a field coil than have to rewind the armature.  a field coil a reasonably handy fellow could make with a bit of effort, or remove and take to a rewind shop to have replicated.

with the selenium rectifiers having gone up in smoke, i am concerned that maybe the fields have shorted? 

also final thought, (sorry for the disjointed response)

remove both sets of field wires from "X" and "x" and do the continuity check as described
and also check between each field wire to the case ground, to see if there is any short to ground.

if you don't have a short to ground, that is a good sign, if you have a resistance reading from say ~10-100ohms or so, i think you would be ok.

when you flashed the field with 24 volts, did you get a huge arc, or just a small flash or spark?

now i am rambling

what output voltage do you get when you apply 24volts to the "x" and "xx" connections?
is that when you get the 16.35volts output on all three phases?

the fact you report and even 16.35 to all three phases, leads me to think this is a field problem or an excitation voltage problem, and not an armature problem, which is good in my opinion. not that problems are good, but an armature problem can be expensive to resolve.

does the reported 16.35 volts reading come from checking between each pair of the three phases? 

can you check between the neutral connection and each of the three phases?

also so that i am clear which animal you have, is it the schematic in fig 3 page 5?

i have a few other thoughts, but lets start with these,

bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 23, 2021, 02:41:08 PM
sorry for the long response, didn't see the pictures before i posted

it looks like the slip rings are nice and bright, so that should be ok

i also see the field wires connected to your new rectifier bridge, the two blue wires look to be the field wires, so remove one or both to do your continuity checks.

i don't see a voltage adjust transformer, so i would expect that your unit is fig2 instead of fig3?

the fact that you can flash the field tells me that the field windings are not open, that is if you remove the field wires and can flash through the wires and see a spark?  the field coils are generally connected in series, so if you are getting a spark then the coils aren't open.

from the rectifier the field wires don't go up into a control panel and are connected to a switch or a fuse or breaker do they?  do they appear to go directly to the field coils?  the schematic does not show a switch/fuse/breaker, but that doesn't me one or more might have been added later or as some option?  make sure those blue wires go directly to the field coils and not to some other thing that might be an issue.  but then again, if you have continuity, then even if there were other things they would be good.

hard to diagnose by keyboard!  :)

let me go back and put together a check chart, with a list of things to check, maybe the problem will be apparent and jump out at one of us or someone else following the topic.

good luck


bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 23, 2021, 05:23:47 PM
Hi Bob

I had a small flash when the 24v dc was removed from neg leg.

With one leg removed I have 28 ohms and continuity between x and xx

No voltage adjust transformer is fitted, so fig2 is correct.

Only fuses and meters up in the control panel, so not affecting output.
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 23, 2021, 05:27:46 PM
Hi Bob
When flashing x and xx should they be disconnected from the rectifier?
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 23, 2021, 05:40:18 PM
a small flash, so your fields should be good, the 28 ohms seems about right too.

can you check the voltage on the field wires while the generator is running, check to make sure you have voltage there and let me know what it shows.

also check the  voltage between each phase on the rectifier and let me know what you get there. while it is running of course.

bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 23, 2021, 05:46:51 PM
When applying 24dc to x and xx should they still be connected to the rectifier?
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 23, 2021, 05:50:46 PM
can you check the voltage on the field wires while the generator is running, check to make sure you have voltage there and let me know what it shows..???

The field wires? Is this between x and xx  and should they still be connected to the rectifier or disconnected?
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 23, 2021, 06:39:26 PM
When I disconnect the field wires from the rectifier and apply 24 Vdc  from the battery directly to the rectifier I get 15 volts across each of the 3 phases and 9 volts from the neutral. The engine is running during this test.
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 23, 2021, 06:44:55 PM
When I disconnect the field wires from the rectifier, x and xx, run the engine I get 0 vdc from them
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 23, 2021, 07:21:53 PM
ok let me see if i can clarify my question

with the engine running:

1. with the field wires connected to the rectifier, check the voltage at x and xx, and note the voltage.

2. remove the two field wires from x and xx and apply 24 volts, and then check the 3 phases to see what power output you get, and note the voltage

3. with the two wires removed, and with them connected to 24 volts, check the output on the two x and xx posts of the rectifier, note the voltage.

4. with the two wires removed from x and xx, and connected to 24volt, check the voltage on each of the input posts of the rectifier, note the voltage.

at some point we are going to get to the bottom of the problem, so be patient and we will work through this thing step by step.

i think we have an excitation problem
what i am starting to think is you are not getting excitation to the field off the rectifier, either the rectifier is bad (possible), or the AC coming off the transformers that feed the rectifier is very low or absent (also possible).

so i guess what i am getting at, is we start at the easy point and work our way upstream and along the way something will pop up and rear its ugly head.

been my experience on engine driven generators, it will turn out to be something simple, and easy to fix (9 times out of 10) the other times it turns out to be something more serious (maybe 1 in 10).  so i think your odds are fair it will be something simple, the only issue that makes me think otherwise is "why" did the original selenium rectifier shoot craps, and yes i am aware that they can die of old age or moisture ingress. i don't think it was a short, else you would have a larger spark when trying to flash the field and the 28ohms seems about right for a field.

i have to leave to take mom on errands and won't be back till this evening (kansas time), meanwhile see what you can check from the listed items, and i will think about a methodical approach to diagnosing the problem.

some of the steps to diagnose come automatically to me, if i had the unit here in front of me, i spent the majority of my career working by myself, so i never had to explain things to others when it came to diagnosis... it is something you just do, while computing what to do next. 

we will get there!

bob g

Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 23, 2021, 07:28:51 PM
Bob you are fantastic, many thanks for taking the time to help me, it is truly appreciated.
By the way I am near Birmingham in the midlands in the UK.
I will respond later this evening.
Al.
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 23, 2021, 09:01:34 PM
hi Bob

with the engine running:

1. with the field wires connected to the rectifier, check the voltage at x and xx, and note the voltage.

4.5mv dc

2. remove the two field wires from x and xx and apply 24 volts, and then check the 3 phases to see what power output you get, and note the voltage

15.7 v ac on 3 phases

3. with the two wires removed, and with them connected to 24 volts, check the output on the two x and xx posts of the rectifier, note the voltage.

177 v dc

4. with the two wires removed from x and xx, and connected to 24volt, check the voltage on each of the input posts of the rectifier, note the voltage.

287.7 v ac across 3 phases.

Hopefully some good data there?
Al
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 24, 2021, 12:06:06 AM
ok

this is what i am thinking now that we have some data to work with

one or the other of the following needs to be checked, as either might be the cause

a. you might have a defective diode or more in the rectifier bridge, or

b. the brushes are dirty, and i am suspicious of them being so.


the slip rings look bright and shiny, did you clean them? or did it come that way?
have you cleaned the brushes?

reading your results, it appears that you have virtually no voltage with the field connected to the rectifier bridge,  while the voltage jumps up to 177vdc on the rectifier with the field disconnected.

what i am thinking is this,

if the brushes are not making good contact, there will not be enough power transmitted across the brush to sliprings or rather visa versa, when the field load is applied. it wouldn't be the first time that i have seen full voltage on an open circuit but have it fall away when the load is applied.  and it appears from your report that is what is happening.

when you apply 24volts to the field the voltage climbs up to something like we would want to see, or close to it.

so the field has two possible sources of power,

1. when you provide 24vdc direct to the field, then you get output

2. when you leave it to the original source to the field you have no output.

so we need to start at one end or the other in the current supply to the fields, and i am thinking maybe start with the brushes first, as they are pretty easy to eliminate.  are they connected to the brush holders with bonded copper cables? i assume so,

as stated earlier, put a piece of 200-400grit paper with the back side on the slip ring and the abrasive side facing the brush, and work the paper back and forth with the brush spring providing the contact force, a few stroke and you will see some powdered carbon, that should be good enough, do them all.

if you didn't clean the slip rings, give them a bit of scrubbing just for kicks.

let us know how you come out

i am still thinking about this machine! and i think we are getting closer to the root cause.

bob g

Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 24, 2021, 12:47:26 PM
Hi Bob
I had previously cleaned the  brushes but have done the brushes again this morning with 400 grit paper. It has not made any difference.

The rings I have rubbed with some 3m scotch brite.
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 24, 2021, 12:51:19 PM
To recap slightly. I have zero dc voltage coming from the stator.
What are the likely causes for this?
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 24, 2021, 12:56:47 PM
I have continuity between all of the slip rings and brushes. So metering between ring 1 and 2 gives continuity, 1 and 3 and 1 and 4. Is this right?
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 24, 2021, 01:02:23 PM
Another question.
When flashing the stator windings do you do it either engine running?
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 24, 2021, 02:43:35 PM
ok silly me, i never thought to actually read the complete manual, but it has a diagnostic flowchart near the end of the manual.

page 11 i think with the info you have provided tells me what i was thinking we were closing in on, but didn't want to say.

from your information

you stated you ran the engine, connected 24volts to the field and got 170volts between each phase coming off the machine?  iirc that is what you found.

if you go to page 11 and follow down the middle of that page, you will find a section wherein

"start the engine, and if the voltage output is still low, apply 24volts to the field... and if the output is approx 220 for a 420 volt machine or ... 170 for a 220 volt machine..."

then to the left of the flowchart,

if the voltages are equal between phases... (and i believe you report that)

then below that on the left column

"fault is in the OREX unit"

"inspect transformer and replace if necessary"

*** insert here:  in the flowchart it tells us to disconnect the capacitors from the output and recheck, so follow the chart and do that next and see if it is "possible" that shorted capacitors could be the fault. it doesn't seem likely to me, but check none the less as the following is much more involved.

back to follow "inspect and replace the transformer if necessary"

so, i think if the aforementioned is correct, that is if you have ran the engine/generator and if you have applied 24 volts to the field connections and if you had equal voltage reading off the output of either 170 or 220, then the only thing left is the transformer unit.

we will then have to pay special attention to that unit
and check all connection carefully, clean and inspect and tighten everything
check for continuity through the windings, check for shorts to the steel laminate cores,
and check for signs of overheated windings, flaky insulation, etc.

i have no idea if a replacement is available for the unit, or if so it is affordable.

so if we find that there is shorts or some other fault in the windings, and no other transformer is available, you have a choice to make...

1. scrap the project, (certainly not something i would do)
2. find a rewind shop and have them rewind the transformers, or
3. take on the rewind project yourself.

the transformer should be fairly straightforward to rewind, as the core lamination's are similar to an audio output transformer wherein the E and I lamination's are not interleaved. the E lam's are all together and the I lams are riveted together. so you can remove the I lamination stack (be careful to note the packing shim stacks, measure them carefully and put them away somewhere safe)  then the coils can be removed from each leg of the E lamination's.

i don't know if the individual coils are wound on bobbins or not, if they are that makes life a bit easier, simply unwind the coil noting the number of turns, number of turns to each tap, and wire size, it appears that there will be two sets of windings, one over the other, one set of smaller gauge wire, one set of heavy gauge wire.  keep careful notes of how each is wound, and if there is a separator paper between the two sets of windings and all taps.

then find a supplier for the magnet wire, get more than you need, it can be found at a motor rewind shop, explain to them what it is you are doing, and they will generally sell you the wire, and in some cases they will give you enough wire for the job.

if you don't have a bobbin, you will have to make a wood form that has the same dimensions as each leg of the E lamination stack.  be extra careful to provide stops to keep the coils the same length as the originals, because they have to not only go back on the leg of the E stack, but allow the riveted I stack to be able to fit back and contact the E stack (the shims will hold them apart, but we want the winding coils to allow for contact between the E and I stacks)

then it is a matter of setting up to rewind each coil, with the taps, and insulation as the original.

trial fit the coils, assemble the transformer, make the connections and test the output.
if all is good, as it should then be, take it all back apart again, and take the transformer to the motor shop and have it vacuum dipped and baked. that will set the windings, and provide for better insulation that will last as long as the originals.

of the three rewind area's of your generator, that being the field, armature, transformer
the transformer is in my opinion far and away the easiest one to rewind successfully.

i had hoped that we wouldn't have got to this point, but if as you reported earlier with 24volts to a running generators fields you got an even 170 or 220 out of the machine on each phase, there really isn't much else to be looking at.

at this point i would be taking a very critical look at all the transformer connections, the condition of each of the coils, continuity, grounds/shorts and if possible take it to a motor shop to see if they can do some meggar test, growler test or whatever to determine the health of the transformer. then depending on the test outcome, the direction will be apparent, and possible decision made.

Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 24, 2021, 03:28:32 PM
Ok Bob Iíll work through that, Iíll keep you posted.
Thanks.
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 24, 2021, 06:18:24 PM
I have disconnected all transformer connections and done some tests as below.
There are no shorts to ground.
Continuity between in put and out put is good.
Not sure how to test tappings, but again no shorts here or indeed any continuity with anything on the tappings.
I have a megger and all cables have very good insulation.
All three transformers behave the same.
Is there anything else I can do?
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 24, 2021, 08:56:32 PM
man,, there is something we are missing here!

now that you have the transformer out, and i assume all the leads can be taped off
so we can do some more testing?

if so, lets power up the field (blue wires) removed from the rectifier x and xx

put 24vdc to the two wires

start the engine and bring it up to speed,

check each phase on the output again, a-b, b-c and c-1 and note the output voltages
lets make sure we are getting relatively even voltage on each of the 3 phases

lets see what we get from that.

if you get somewhere around say 170 volts or more, can you apply a load to that? like a brush motor circular saw?  you guys use 220 single phase in england iirc?

the idea being i would expect the phase to hold a relatively steady output with somewhat of a load.

maybe an electric heater or something?

i have a load bank here that i can provide a load for about anything from 12 volts to 240volts, but you are there and i am here, so that doesn't help.

something else came to mind a bit earlier

you mentioned in the OP that the unit was recently acquired and had been sitting for 10 years?  and the selenium rectifiers released the magic smoke (toxic as it is).

there is a real possibility that someone was monkeying with the internal connections trying to make the thing work sometime back before it was put to rest (over 10 years ago).

it might be something a stupid as some wiring connections that have been moved around and not connected correctly.  this might explain why the selenium rectifier burnt up, when the problem originally was it probably just needed the slip rings cleaned up.

so, do the above test if you can

and if you are fairly confident the transformer is good, then i would suggest going to the schematic fig2 and go through every single connection to make sure everything is connected correctly.

i also read in the manual that a provision to shut down the field could be accomplished with the addition of a 15amp switch to short the field.  this i find quite strange, as a shorted field would through a lot of heat on the rectifier and transformer i would think.  however the manual states this as a possibility, so you need to check to see if there is a switch in the panel somewhere?  it is unlikely there is one, because how are you able to get 24 volts to the field if there is a blown switch?  but then again, maybe under load the 24volts isn't really 24 getting to the field coils?

can you take pictures and post of the transformer, from front and back, i would like to have a look at them.

i assume that the unit failed before it was put into storage, and left to sit for 10 years, what we don't know is who or what happened after it failed, and what was done to try to get it going again... that is always a big red flag in my book.

a lot of guys won't touch electronic equipment that has had other hands messing around in the insides,  not unless they specialize in that particular piece of equipment and have the exact schematics and other resources.

i recall a Zenith TV repairman years ago, he was about to retire and wanted me to take over the business... he told me "never ever, work on anything you don't have a schematic for, and never ever ever work on something someone has made a mess of"

now i don't know if that means it will be a real pain to fix, or something that in his experience can't be fixed?

a generator however is a rather simple piece of equipment and we have a schematic
so we are missing something,

so lets tape off all the loose wires, remove the field wires from the rectifier, power up the field, start the engine and see what voltage comes off each phase of the armature, note the readings, and then lets apply some load and see if the voltage drops like a rock or remains somewhere in the same area.

lets do that first

then lets take some pictures of the transformers and post them,

then lets reinstall the transformers and check each and every wire, to make sure it is connected according to the schematic.

and finally

are you absolutely certain the rectifier bridge is good?  i know you installed it to replace the selenium rectifier, but we sure don't want a bad replacement part to drive us crazy chasing other directions assuming it is good.  i don't trust any part these days!  and i don't much care who makes the part, it seems failure rates are much higher than they used to be.

this is turning out to be a fun project  :)

bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 24, 2021, 09:11:09 PM
Ok Bob I will have ago at that tomorrow.

When I fired it up for the very first time I had 400 + volts show on the volt meter, after about 30 secs I thought I saw the volt meter increase considerably and by that time it had started to smoke so I shut it down.

I have tested the bridge rectifier and it is ok. All six readings are good.

Al
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 25, 2021, 12:43:04 PM
Hi Bob

I sprayed the coils and wire with a good anti tracking spray.
The thicker cables run right back to the brushes.
Not sure how I test the phases without these attached.

Al
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 25, 2021, 03:18:10 PM
test leads right to brush holders
or if that is too hard connect some short wire leads

bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 25, 2021, 04:37:06 PM
See pics of set up.
I,m getting 268 v across phases 1,2 and 3 and 169v across a phase and neutral.
I will try and find a kettle to put the single phase under load?

Al
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 25, 2021, 04:58:24 PM
Ok, with a 2500w kettle plugged in the single phase and neutral the voltage dropped from 169 to 159.
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 25, 2021, 05:50:38 PM
ok, cool
that tells me that the field and armature along with the brushes and slip rings are good
so we have a basic machine that works

now we need to track down every friggin connection from the brushes to the transformer to the rectifier and then to the field

the problem is not in the basic generator itself,

with that big ass control box on top, i am wondering the wires coming off the brushes obviously go up there so that they can be applied to the output posts, so i am thinking that is where they also T off to come down to the transformer pack

do you have a picture of the innards of that control box?

i as well as you should be happy that the basic generator is doing what it should, it now comes down to finding the wiring fault

what i am saying, and forgive me if i am telling you something you already know, is...

with you supplying the field with 24vdc and getting an output voltage to an approx 2500 watt load, and noting the 169 vac dropping to 159volts tells us that the generator is doing what i would expect it to do... i would expect a few volts drop as there is no regulation that would normally be provided by the transformer action by design.

this outcome tells us that with excitation current (24volts in this case) the machine can make power.  so the problem is with the original excitation system, which is comprised of the transformer pack and the bridge rectifier.

you have tested the bridge rectifier and it tests good, so it leaves us with either the transformer pack, or something between the brushes and the transformer pack that might be located within that control box.

i don't see anything on the schematic, however it is not uncommon to have some other option either added by the OEM or by someone else after installation in the control box.
and that would not necessarily show up on the generic schematic.

what we have in the manual is a generic schematic, and from experience manufactures make changes over time and publish differing schematics to account for changes in design. 

so lets open up that panel and have a look? 

and if you can provide pictures (front and back) of the transformer pack, i really want a look at it too.

bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 25, 2021, 05:55:59 PM
sorry i missed the pictures of the transformer

take a good look at the windings, do i see copper showing where the varnish has chipped off?

some of the older varnishes look black, i can't tell from the pictures if that is the case, or if the transformer has been overheated and has some shorted winding.

if it has some shorted windings, it probably cannot put out any power,

bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 25, 2021, 06:03:00 PM
Do you know how to test the windings?
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 25, 2021, 06:50:05 PM
probably the best way would be to take it to a motor shop and have them test it.
take a copy of the schematic, for that matter a copy of the manual that you linked to.

i am looking at the last picture you posted of the transformer, i believe it to be the back side.  the center coil looks to me that is has been very hot, but again pictures can make things look different than they are in person.

but i am very suspect of that transformer, and if follows the flowchart telling us the transformer is the problem.

does it smell burnt? 

bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 25, 2021, 07:05:25 PM
Nothing about it makes me think itís over heated, but I will take it tomorrow to be tested.
Let you know ASAP.
Thanks
Al
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 25, 2021, 09:41:36 PM
something occurs to me, that you can easily check

the little white plastic junction strip mounted on the lower part of the transformer unit, it is not original equipment.

what i don't know is this...

does the output wires going to the load connect through this strip normally?

i think the load wires are connected to the strip? it looks that way in the schematic.

what concerns me is this, that type of junction strip or at least some of this type aren't really capable of transferring the amount of power the generator is capable of through the strip bus.

you might take a look and see, check each to see of there is continuity across them, and that there is no signs of overheating there. 

its a reach, and i can't tell from the pictures, but if as it is my experience the terminal strip cross connector(s) might be blown out like a fuse having failed.. and we would assume the connections to be good when maybe they aren't?

doesn't take much to check out and see.

again we know that the basics of the generator are good,  i went back and reread the manual and the diagnostic flowchart "again" (funny how one learns a bit more with each reading). on page 11 left column, second group

where it says voltages correct and equal, and from above (center) the voltage should be approx 170vac and you got 169...

the flowchart then says it is a problem with the transformer (OREX), to inspect and change if necessary.

so everything is telling me it is a faulty transformer, however it may be the terminal strip with bad conductors, or someone has misconnected things? 

we are cornering this gremlin!  he ain't gonna get away from us!  ;)

bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 25, 2021, 09:48:26 PM
Yep it seems to be pointing at the transformers, Iíll get them checked tomorrow.
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 26, 2021, 11:06:20 AM
Morning Bob.
I think itís going to be a good day!
I didnít go to the motor rewinds CO.
It was bothering me that I could not get any response from any of the tappings , so I stripped down the connector block to double check everything.
I found that all my connections were sound and then it hit me.
The magnet wire is enamel coated! I didnít know that, but I do now.

So in the process of burning off and sand papering down to metal.
Update you later!
  :)

Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 26, 2021, 01:11:10 PM
well i am rooting for your success!

hopefully that will be the problem, and making good connections will clear up the problem.

bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 26, 2021, 01:12:22 PM
Bingo! 427 volts each phase!
Enjoyed every moment :)
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 26, 2021, 01:16:04 PM
well now, how about that!

now go through the unit and clean, check, tighten and secure every single wire!
and make sure that everything is neat and secure, remember vibration can cause chaffing which leads to shorts and bad things happening.

i think you will be very happy with this generator!

happy as heck it all worked out.

bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 26, 2021, 01:20:51 PM
Will do thatís my style.
Many thanks for your help, couldnít have done it without you.
If you ever need any thing sourcing from the uk let me know and Iíll try and help.
Regards
Al
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 26, 2021, 01:34:09 PM
btw

if the load wires connect to that white terminal strip, which the schematic indicates, then i would highly suggest getting a much heavier duty strip. if on  the other hand it is only a terminal strip to provide connections to and from the rectifier and the field coils it is probably adequate.

if it were me i would upgrade in any even to something rated for 30amps per terminal
one that uses wrapped screw connections, rather than binding connections.

one like this

https://www.ebay.com/itm/113523575101?epid=23027620928&hash=item1a6e88493d:g:w2EAAOSwkFZcMBCs

you should be able to source one there in England somewhere.

in my experience they hold up much better to vibration, heat cycles, and make a much better connection that seems to last much longer than the type you are using.

those white plastic binding type seem to do better in a non vibratory and stable temp environment. 

and lastly to add to the prior post on wire/cable dressing

be sure to gather up all the transformer wires and sleeve them with insulation, and bind them together  or to the frame so that they don't move around, you don't want a wire wriggling around to the point it breaks off close to a coil, that would be a bad day that is easily avoided.

i don't know you experience, but if you can take a look in a engine driven welder, you will note that they don't leave anything unsupported, every wire is secured and protected so that vibration doesn't allow them to move around and abraid themselves or fail due to flexing.

this unit should provide years of service to you.

bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 26, 2021, 07:28:58 PM
Hi Bob
All points noted.
The connector block is rated at 32amp but I will look for something more OE.
In the the attached photos what do you think is the round item. Looks like a buzzer ?
Al
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 26, 2021, 10:49:35 PM
i have no idea what that little round thing is, as the oem schematic doesn't address the control panel, it makes me wonder that the generator was manufactured under various names each of which had their idea of what the control box should have in it.

it kind of looks like a buzzer to me to, can you chase down where the wires that feed it come from?

btw, the lacing of those two wires look to be of a very high standard, whoever did it was darn sure proud of his work, and i am impressed!

the following is a digression

i have been following this gentleman on youtube who has a long history of video's pertaining to ham/amateur radio.

last evening he was going on about new guys not buying used equipment and as a teaching aid he used his fairly recent purchase of a used (20 odd year old) homebuilt 2 seat kit airplane.

it had problems that weren't found in the annual inspection or by the airframe experts.

one of which as a cracked pitot tube feed hose, old and cracked which one might expect from an old plane that had been sitting in the desert heat for years, and worse he got a call from the mechanic that was tasked with replacing the line, that there was fuel leaking everywhere!  turned out the old green transparent line was cracked and leaking badly too.

what i found interesting while watching the video was the routing of those hoses, particularly the fuel hose, laying all about from the wing tanks, down through the frame, up over the firewall and drooped down over the side of the engine... no where was it secured properly... and for some reason that wasn't noted either!

the lacing job on your mystery buzzer part, looks to be what i would expect from an aircraft production mechanic... first rate.

based on that alone, i think your generator was built at a time when quality meant something! and people took pride in their work. especially when it came to places where most people would never see it.

i like that! a lot!

today it seems like folks just throw crap together, add a couple of zip ties and it is good enough.

bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 26, 2021, 11:06:14 PM
those two laced wires aren't connected in series with the field winding wires (blue wires, x and xx) are they?

seems like if it were some sort of warning buzzer, it would be pointing out the front of the panel, and have some sort of egress so it could be better heard.

i wonder if that is some sort of early breaker? maybe?

with the stamp steel standoff, it makes me think that it doesn't protrude out the end of the case? or does it?

interesting.

more to learn from this machine yet ;)

bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 27, 2021, 01:15:37 AM
It came to me where i saw one of those little round things, not exactly the same but similar
it was in a 1950's marquette battery charger, it also had selenium rectifiers, and it had a breaker that looked alot like that round unit, it just had heavier posts on it, maybe 1/4" or so.

i got that charger given to me because it didn't work, got it working and had it around for years, all my buddies called it "R2D2" because of its resemblance  to the star wars robot.

always hearing "hey somebody know where R2D2 is?" around the shop...

i gave it to a buddy and i suspect ol' R2 is still being drug around to charge up someone's hotrod.

bob g
Title: Re: Lister HA and Brush RS1B generator
Post by: Adscnc on August 27, 2021, 08:11:27 PM
Yes the lacing of the that pair of wires is a work of art.
I wondered whether it might be something that measures amps as it is wired into the voltage /amperage display switch.
Al
Title: Re: Lister HA and Brush RS1B generator
Post by: mobile_bob on August 27, 2021, 11:22:45 PM
well darn

it might be some sort of power resistor, for voltage dropping? 

seems a bit crude, but if so, and it does the job, maybe it served a purpose
and allowed the use of some other parts that were available at a low cost to the oem?

if you feel so compelled, you might take it out and get more pictures of it, i am just curious
so it is not important to do so unless some function of the generator is not working properly that it might be related to.

if all is good, maybe somethings i just don't need to know! :)

bob g