Rick Jay and Carsten
Which would be the better system?
Option A)
Mounting a 41kw 240 volt AC SEW motor used as a Motor/Generator with 7 x
48 volt DC batteries in series running into the DC input of the Freq
drive. Install extra alternators on the Diesel to charge the 12 Volt DC
batteries for the 12 volt DC systems which also run the inverters for
the 240 v AC systems. I'm not sure how the generation system would work
AC to DC?
Option B)
Mounting a 41kw 240 volt AC SEW motor used as a motor "only" with 7 x 48
volt DC batteries in series running into the DC input of the Freq drive.
Then install a separate Genset to charge the 48 volt DC and 12 Volt DC
batteries for the 12 Volt DC systems which also run the inverters for
the 240 v AC systems. Use 240 volt 3 phase AC appliances (compressors)
when Genset is running.
Option C)
Mounting 2 ADVANCED DC #FB1-4001 Series Motors..28 HP cont., 72-144
VDC..85 HP peak, reversible, double shaft (which equals 42 kW) joined at
the shaft ends. (this may require two controllers) Apparently these
motors don't like being used as a generator! So then either a Genset or
additional motor mounted as a generator will be required.
Option D) Something we haven't thought of yet!
Over to you guys my head is hurting just thinking this through! I think
its better to get this sorted before I start and get into situation that
you are describing Carsten.
Regards and Thanks
Steve P
-----Original Message-----
From: owner-personal_submersibles@psubs.org
[mailto:owner-personal_submersibles@psubs.org] On Behalf Of rick miller
Sent: Wednesday, 1 March 2006 7:00 AM
To: personal_submersibles@psubs.org
Subject: Re: [PSUBS-MAILIST] RE: DC Motors
Stephen
a standard 50 HP freq. drive setup for 460 ac. will run on 620 dc at
about 87% eff. yes that is 52 12 volt batteries. it might make sense to
go
to a 240 volt system requiring only 26 batteries. and 600 volt standard
insulation and arc gaps. this would be standard industrial 480 volt
switch
gear. At 240 ac output 310 dc input you are looking at a 200 amp load at
full power. a new freq drive at set up for remote monitoring and
control.
here is a forty that is on ebay now
http://cgi.ebay.com/ALLEN-BRADLEY-1334-JJB-S2-AC-MOTOR-DRIVE-40HP-ADJ-FR
EQ_W0QQitemZ7539191916QQcategoryZ42894QQssPageNameZWDVWQQrdZ1QQcmdZViewI
tem
recharging from a standard genset unit. since you will be charging
batteries and running the vessel you will probably want a 100 kw genset.
the nice thing about this is that you can do multiple taps for your
different voltgae requirment.
----- Original Message -----
From: "Carsten Standfuss" <Merlinsub@t-online.de>
To: <personal_submersibles@psubs.org>
Sent: Tuesday, February 28, 2006 11:31 AM
Subject: Re: [PSUBS-MAILIST] RE: DC Motors
Hi Jay, goor idear but I am sorry, I have not the space for a 40kw
AC-DC
MG setup. Also the efficency is with 0,9*0,9 = 0,81 not very hig.
Produce at input 40 kwh just 32,4 kw power and 7,6 kw of heat..
best regards Carsten - but is my second option if the black box
Dc400v-Dc600v-Ac400V 0,95% box development fails..
Jay K. Jeffries schrieb:
Carsten,
You might consider a motor-generator (MG) setup...a linked combo of a
DC
unit that can operate as a motor or generator and a AC unit that can
operate
as a motor or generator. These were used on older diesel boats to
generate
the high voltage and or frequency required to operate some
electronics.
On
present day nuclear subs, the MG resides between the steam turbine
generators (SSTG) and the batteries. When charging the batteries,
the AC
unit is a motor and the DC unit the generator. When drawing power
from
the
batteries, the DC unit is the motor and the AC unit the generator.
Under
normal ship's electrical load with the SSTG on line, the MG set would
be
slowly discharging the batteries to keep them in condition. On a
loss of
SSTG power, the MG sets convert the DC power to AC. The system was
aligned
in a port & starboard cross connected system for redundancy. I'll
try to
lay out an ASCII schematic; the "X" indicate isolation switches for
spitting
systems or isolating faulty components/wiring:
(DC load side) (AC load side)
_____ MG ____X______ SSTG
| |
X |
| |
BATTERIES X (normally open)
| |
X |
|_____ MG ____X___|__ SSTG
Your boat could be wired in a similar manner where the diesel
generator
is
substituted for the SSTG. Your main motor(s) could then utilize the
efficiency of using high voltage and lower amperage units.
Respectfully,
Jay K. Jeffries
Hi Stephen I got this way an run in trouble..
On euronaut I build a 400 V 40 kw DC Motor in - and use them as motor
underwater and generator on the surface - direct to the 400 V DC
batteries. That was the idear - But first highpower Dc technologies
is
old technologies and not so much parts are available anymore.
The real trouble beginns when you realise that both bilge Pumps have
400 V AC - both compressors have 400 V AC and other subsystem like
chargers etzc also.
The converter to make from 400 V Dc just 400 volt AC ist not off the
shelf.. To make 400 AC you need at least a DC Voltage of 600 Volt..
So I need now a highpower DC-Dcconverter which make from 350-450 V DC
a
600-700 V DC and than a DC-Ac converter to make 400 V 3-phase AC..
Maybe it is easier to go with a AC system today.
Make shure that you have all your subsystem on your list before you
decide which way your go. To rebuild all subsystem back from AC to DC
will be a nightmare.
48 V DC for a 75 kw output are very, very strong cables..
75000 watt / 48 V = 1563 ampere..
best regards Carsten
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