Author Topic: Brush Wiring Diagram E9840322  (Read 815 times)

LHCRT

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Brush Wiring Diagram E9840322
« on: August 17, 2018, 12:28:56 PM »
Hi.

The Lichfield Canal restoration group have a Lister Diesel No. 7**3SR121 attached to Brush alternator 2/55343 22, which is not working. Has anybody got the wiring diagram E9840322 please?  We've found a clamp on one of the resistors broken, so are going to fix that.

There are three rectifiers fitted - two original ones with fins and one new 'solid state' replacement. I assume the excitation of the stator is by DC (the output is from the rotor).  Will the alternator 'self excite' after long disuse or will it need a battery to be applied?

Cheers.

ajaffa1

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Re: Brush Wiring Diagram E9840322
« Reply #1 on: August 17, 2018, 11:39:49 PM »
Good Day and welcome. I posted a scan of the startomatic drawing last night under a different thread, so here it is again.

Bob

oldgoat

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Re: Brush Wiring Diagram E9840322
« Reply #2 on: August 18, 2018, 02:59:05 PM »
Throw away the old finned selenium rectifiers and replace them with solid state diodes it will save you grief later

ajaffa1

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Re: Brush Wiring Diagram E9840322
« Reply #3 on: August 19, 2018, 12:35:24 AM »
I completely agree with Oldgoat. Replace all rectifiers with modern silicon, the bridge rectifier for the auxiliary field will require a heat sink. There are also two radio frequency suppressors (one for each slip ring) these are almost certainly shot after 50 years service.

Bob

SimonC

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Re: Brush Wiring Diagram E9840322
« Reply #4 on: February 05, 2019, 11:54:20 AM »
Hi, I'd like to re-introduce this thread. I am another member of the Canal Trust and am trying to take up and fix the problem with the generator. The generator is a stand alone unit meant for site work and not a Start-O-Matic. It generates either 115VAC or 230VAC (switchable between the two). When I took the end covers off there are four slip rings and what seems to be two sets of rectifier/resistor packs - one has a single resistor and a replacement silicon rectifier (no heat sink) the other side has two smaller resistors and two selenium rectifiers. I am no electrical engineer but am guessing there are two windings on the rotor giving 115VAC which are connected either in parallel to give 115VAC 25 amps or series to give 230VAC 12.5 Amps. It would be nice if someone could supply a copy of the wiring diagram rather than me having to grovel in the dirt trying to draw my own.
I also really need help to size up new replacements for all the rectifiers - both the selenium and the 'new' replacement at the same time

Simon

PS This is my first post - I will try and post some pictures when I find out how. 

ajaffa1

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Re: Brush Wiring Diagram E9840322
« Reply #5 on: February 05, 2019, 10:18:06 PM »
Hi Simon and welcome. I have not seen a four slip ring unit before, some photos would help. It is easy to post pictures: after typing a message, click on the "attachments and other options" button bottom left of your screen, alternatively you can cut and paste.

Does this unit have the starter motor integrated into the generator head (commutator ring and four carbon brushes) or does it have a separate starter motor and alternator bolted to the engine?

For replacement Bridge rectifiers I have used these successfully: https://www.ebay.com.au/itm/Hot-1600V-Bridge-Rectifier-Full-Wave-Single-phase-Diodes-60-100-150-200-300-400A/362071126663?hash=item544d1ef287:m:mtqKtCyYNzBG_O955-pmx4A:rk:19:pf:0

I`m sure you can find them on Ebay.uk, the cheapest 60 Amp units will be more than adequate to feed the two auxiliary windings but they will need a heat sink.

The third rectifier is a bit of a mystery. If your unit has the integrated starter motor then this is probably just a diode in the battery charging circuit to prevent the battery discharging through the starter windings, in which case pushing the starter button will energize the main field windings (no need to flash). If your unit does not have the integrated starter motor then this rectifier is probably used to feed the main field windings and it would be these windings that would require flashing.

Good luck,
Bob




SimonC

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Re: Brush Wiring Diagram E9840322
« Reply #6 on: February 06, 2019, 09:05:19 AM »
Thanks for the quick reply Bob and for the help with pictures (I was trying to follow the instructions regarding the gallery). I have attached some photos of the slip rings and rectifiers - the engine is manual start only - no battery. The output is switched either 115VAC or 230VAC. I haven't traced the wiring yet but think the 115v side is the twin rectifier/resistor setup with the larger single resistor being on the 230V side.

Many thanks
Simon

ajaffa1

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Re: Brush Wiring Diagram E9840322
« Reply #7 on: February 06, 2019, 10:59:59 PM »
Hi Simon, thank you for the photos. I believe that the smaller(new) bridge rectifier will be connected to the main field, output voltage is adjusted using the large rheostat. The other two will provide current to a pair of auxiliary fields, compounding(speed of recovery to an applied load) is adjusted using the two smaller rheostats.

Interestingly your photos show 3 fuses but only 2 outlets. I am unsure what this third fuse would be for. I suspect that you have two 115 volt feeds coming from the generator and that the switch will put them in series to produce 230 volts.

My best advice would be to photograph everything as you go. Label every wire so you know where it goes. The polarity of the field windings is critical. I suspect that the wires originally had coloured shrink wrap ends to identify them, you will probably find that the live and neutral AC wires have black heat shrink while the +ve and -ve DC have red and white heat shrink

Keep me up to date with how you go.

Bob

SimonC

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Re: Brush Wiring Diagram E9840322
« Reply #8 on: February 11, 2019, 02:56:35 PM »
Hi Bob,

SimonC

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Re: Brush Wiring Diagram E9840322
« Reply #9 on: February 11, 2019, 03:10:59 PM »
Hi Bob, I have traced the wiring by hand, jotted it down and produced this sketch attached. Not sure if I got all the wires traced though - I could only see the field wires enter the stator windings. Hope you have more experience of generators to be able to follow the diagram - my own limited electrical knowledge allows me to follow the logic partly but I cannot see the purpose of the two old rectifiers. I plan to replace all three rectifiers with similar units to those suggested but at present do not know which of the field wires would be positive (apart from the one on the new rectifier)

Best regards
Simon

ajaffa1

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Re: Brush Wiring Diagram E9840322
« Reply #10 on: February 11, 2019, 09:36:06 PM »
Hi Simon, thank you for your drawing, very informative and well done. Generally speaking the wires should be labeled with coloured shrink wrap. The AC wires (one to the slip rings and the ones to neutral in the top box) are usually black, The +ve wire to the field is red and the -ve wire is white. Sadly many years of dirt heat and deterioration often make them indistinguishable. However, a close look at your photos shows two of the wires attached to the rectifiers appear to be brown, I suspect these are the +ve field wires.

I am hoping that one or other of the old rectifiers still works, if you disconnect the brown shrink wrapped wires you should then be able to test the two rectifiers with a multi meter. If you set the meter to Ohms, put the red probe on either of the AC terminals (connected to chassis or slip ring) then place the black probe on the vacated rectifier outlet you should get a reading. Now reverse the polarity of the probes, you should get no reading. If this is the case then the two wires with brown shrink wrap are indeed the positives for the auxiliary field windings.

Let me know what you find, please be careful with old selenium rectifiers their contents are toxic.

Bob

SimonC

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Re: Brush Wiring Diagram E9840322
« Reply #11 on: February 25, 2019, 09:32:40 AM »
Hi, The new rectifiers have arrived and I am working out how to fit them to some aluminium channel I plan to use as heatsink. One query regarding the wiring of the replacement for the blue rectifier - when I traced the wiring the resistance appears to be in series with the rectifier, is this normal/correct? or should there be an additional link wire to put it in parallel like on the other rectifier/resistances? I thought the resistance was the means of adjusting the output voltage. Does anybody know?

Beat regards
Simon 
« Last Edit: February 25, 2019, 09:42:00 AM by SimonC »

ajaffa1

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Re: Brush Wiring Diagram E9840322
« Reply #12 on: February 25, 2019, 10:42:16 AM »
Hi Simon, yes I believe that to be correct. The AC voltage generated is dependent on the strength of the magnetic field it is rotating in. The main field winding has an in series rheostat which allows you to adjust the strength of that field and thus the initial output voltage being generated.  The auxiliary field windings provide a boost to the magnetic field, dependent on how much current is being drawn, the more current is drawn the bigger the boost to the auxiliary field windings, thus maintaining the output voltage.

Bob

glort

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Re: Brush Wiring Diagram E9840322
« Reply #13 on: February 25, 2019, 11:16:51 AM »
Hi, The new rectifiers have arrived and I am working out how to fit them to some aluminium channel I plan to use as heatsink.

Old computer CPU heatsinks work well with rectifiers and also if you can get hold of an older Solar inverter, they often have massive heatsinks on the back you can cut down.  They are also good for parts like Caps, mosfets and other bits and pieces that can come in handy.

SimonC

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Re: Brush Wiring Diagram E9840322
« Reply #14 on: February 26, 2019, 12:45:15 PM »
Thanks guys, thought I had better check as it looks like the wiring had been modified to fit the silicon rectifier.

Best regards
Simon