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G8MNY  > TECHNI   04.10.21 09:00l 121 Lines 6720 Bytes #999 (0) @ WW
BID : 48610_GB7CIP
Read: GUEST
Subj: MEDUSA SIP2300 Generator info
Path: PI8DRE<PI8CDR<LU4ECL<GB7CIP
Sent: 211004/0659Z @:GB7CIP.#32.GBR.EURO #:48610 [Caterham Surrey GBR]
From: G8MNY@GB7CIP.#32.GBR.EURO
To  : TECH@WW

By G8MNY                                       (Updated Jul 13)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)

Years ago I bought a MEDUSA SIP2300 4 stroke petrol generators as the were so
cheap (just in case we have power cuts!). It's the seems same as WOLF2.3kW.

It is fairly quiet @ 73dBA @ 4m. The large 12 l tank gives approx. 10 hours run
time. It is not too heavy @ 83kg full, 41kg dry. So to move it by oneself (only
on & off a low level trolley & lift into van etc!)

                                        Gauge   Filler
                   _.==.._   Tube
/~~~~~~Tank~~~~~~~\               /"     Large 12L Tank    "\ Cage
-------------------      Fuel Tap ===========================
\_____________/~~~~      & filter\|"""""~~~~~~~~~~~~~~~"""""|
    Tap(0)   elec            STOP [] OK  on  " AC "      AC
Choke //   Sol\____         SWITCH |_  Oil   = =  = = _|  2x13A
Ŀ  /~~~~~\\.  Pull           ۳~~""---..........---""~~
۳In- ,' /~~~\//\\ Start          ۳F ENGINE      |     |  
۳Take  ( )                   ۳A        (=)oil ALT |  
 \ \___/  /                 ۳N   ________|_____|  
     ' Ŀ `                           
"""""""""""""""""""                

I have modified it for /P contesting, to power several 400W valve PAs for as
per my bul on "Petrol Gennys for /P SSB". With my rev up modification (add a
solenoid for FEED FORWARD load compensation) the measured performance is now...

Generator      Unmodified                   Modified
 Load kW        Volts  Hz               Volts  Hz  Uplift %
   0             255   55                255   55    0
  0.1            235   54                238   54    0.3
  1.0            225   53                234   54    4
  2.0 Rated      215   51                235   54    6.4
  2.3 Old Peak   200   49                233   54   16.5
  2.5            190   47                235   54   23.7
  3.0 New peak   180   45 33% throttle   220   54   22.2  @ FULL THROTTLE!

I do not intend continuous loads over 2kW, just speech peaks etc. to go to 3kW
peak load. Before the modification it was not possible to activate the 10A
thermal output trip on good power factor loads, after this modification it is
now possible!

At 50Hz you only get 220V output, but it is more economical to use lower RPM if
the peak power is not needed! There is no 2 speed option for this generator,
but a long screwdriver will adjust the voltage/RPM setting spring OK. Note the
off load voltage is quite a bit higher than even with a base load of 100W lamp.

Other Mods I did were..
1/ Added earth bonding from engine, to frame, & to electric panel plate.
2/ Added earth lead & earth clip for external earth stake.
3/ Added engine ignition lead screening, & made a screen tube for the plug cap.
4/ Painted Alternator casing black to improve heat dissipation.

CIRCUIT
I have reverse engineered the diagram...
                                                                    STOP
 o/oĿ
 gn/ye         2x13A  Ŀfront      External Earth                
             E   AC    E    __panel                                   
       bk  N   L     N   L  ///                                        
        Ĵ   )       - - - - - - - - - - - - - -         
          )Ĵ          |  ´<       
       Run                    | __D2                 D1  |         
       Neon   10A              | /_\ __              __    |  bk/    
            Trip    bk        |    \_/Q2          Q1\_/    |   wh    
        Ĵ               |     \     ZD  ____/     |         
               rd     Added   |      47Ĵ<Ĵ         
   25u 450V         Solenoid  |              200     |       Oil 
   ĴĿ(155V)     -------  | 50   Ŀ +C1   |      Neon 
                   =====   |       __ 1k C2  ===47u |          
                  _(((()_  |     D3/_\  === 2k  63v  | ye       
   ye  ye           0.2    |  )  
                            |        P C B               |           
 _ _ _ _ _ _  _ _  _ _ _ _ _|_ _ _ _ _ _ _ _ _ _  _ _ _ _| _ _ _ _ _ 
   or  or    rd   bk  |          __  oil       bk              bk/wh 
   1.4      1.8     | Timing |(  o/o         5kĿ   
__ ((() ==== (((()    | Pickup |(  Ĵ               Spark  ||(6k 
///  ==== (((() ====     |  -2V   __  1n ?                 Plug   ||(___
          Ĵ>          |        ///                              ||( 1
     A L T E R N A T O R   |   C R A N K C A S E        M A G N E T O __
                           |                Ŀ               ///
                                       TUBE__ gn/ye __ FAN
                                      FRAME///       /// COWLING
EXCITATION
This is a brushless excitation with the rotor magnetically charged up each half
cycle from circulating 90 out of phase currents from the exciting capacitor.
In the rotor is 4x 3A 200V diodes in series parallel (a small back EMF R)
across the winding to maintain the current half a cycle after the kick. This
system is more reliable than brushes, but does produce a kink in the output
winding waveform.

ELECTRONIC IGNITION
The electronic ignition works in a strange way, as top dead centre approaches a
voltage of -80V or so is made by the magneto primary, this is shorted out when
the timing pulse triggers the SCR, shorting this voltage & producing an
ignition voltage in the magneto secondary.

Only one wire from the crankcase may be just the oil status. The -ve EMF of
magneto appears on Q1 SCR cathode gate & positive going on the gate via D3
47R & ZD, to fire SCR Q1 & short out the coil producing a voltage pulse on the
secondary that makes the plug spark. If there is no oil Q2 is not fired & C1
charges up to light the low oil neon & eventually defeat the ignition after
30 seconds. But I have found in practice that at the point of low oil occurring
when running, there is intermittent ignition (hunting on & off) rate than a
shut off!

(this understanding follows feedback from internet reader Richard Groves)


See my TECH buls "MEDUSA SIP2300 Generator Repairs", "PERFORMANCE POWER 1kW
Genny" & "Petrol Generators for /P SSB".


Y Don't U send an interesting bul?

73 de John G8MNY @ GB7CIP


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