65 Kva Mawdsley Alternator

I have had a very big 3 phase 415v 50 c/s alternator for years now and
at last I need to put it into service.
It was manufactured by Mawdsley in the early 80s and when I shut it
down, I disconnected the AVR too and kept this and the spare I held.
I have checked with the Company and there is no way that they can help
me with the excitation to fire it up. Before I go to all the trouble
of connecting it up to a diesel engine and spin it up to 1500 rpm, can
anyone please tell me a few things about it.
It has a separate excitation generator on the end of the shaft and I
would imagine that this is still in circuit, as I have not been inside
it yet. How does this set up actually work. does the alternator self
excite and the AVR just keep the output within narrow and automatic
limits? Will it produce 3 phase on it's own or is the AVR essential
and in this case is it a standard wiring circuit or will it be unique
to this alternator and AVR setup?
There is quite a lot of information on the makers plates on the two
units, but no information on how to connect it all up. The AVR itself
has a whole lot of wire connections available but nothing to tell me
what goes where. I have spent hours looking for information on the
web, but with no luck.
This is what I wrote to the manufacturer:
Thanks for any comments, It really is a super machine. a bit dirty now
but that will be easy to rectify.
Regards George.
I have had a closer look at the big alternator - which is the one that
I
really would like to see working again. There are two units, the main
alternator body which has the following information:
Mawdsley A/C Generator BS 2613?70 (there is a scratch across the
number)
ser. no. 4FA4KB. 501
KVA 65 ( I thought it was 85, but this is better really as my engines
would
be struggling at 85 KVA.)
Volts 415. Amps 90. 3 Phase. conn. star. rpm 1500.
Excitation volts 71. amps 18 pf. 0.8 enclosure SP?
Then on the excitation generator there is another label:
Exciter BS 2613/70
No. 6R4N3155 rpm 1500 volts 71 amps 18 3 phase hz 50.
Exc. volts 16.5, amps 1.8, ins. class F.
I have two identical voltage regulator boxes made by Emrec but with
your Co.
name on too. Type 4VR ser. no. 1197 (one of them)
30 VDC. 6 Amps.
I am not sure about this, but am I correct in assuming that the
voltage
regulator feeds into the exciter and this is internally fed into the
main
alternator? If so and if the 4VR is the one for this alternator, then
all I
have to do is wire it up and I do have the connections for the 400 Hz
alternator to another voltage regulator 6VR I think they are,I have
two of
these too. I have a small number of explanatory sheets in how the 400
Hz
machines work with their AVRs If you can confirm the 4VR is the one
for the
65 KVR 50 HZ machine I think I will be OK.
Hoping this makes sense to you and that you can shine some light on
the
situation. I wish I knew more on how excitation works - or worked 30
years
ago! Would it be true to say that most alternators use the same sort
of
excitation, and only the details are different between manufacturers?
If
the voltage output of an alternator is only dependant on the loading
and the
DC current being fed into the excitation winding of the exciter, it
may be
that I can build a circuit that does this in a very simple way. My
load is
not going to be anywhere near 65 KVA in any case.
Reply to
George
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