Crompton Parkinson F81A8864 5.5kw 100v 55amp

[Steve C]

My customer has an un-restored C-P dynamo coupled to a restored single cylinder diesel engine.
The brush gear is ropey to say the least, the com looks ok, dark but not scored.
It's compound wound and rated continuous, I think it's 1000rpm, that's about all I can read off the worn name plate, except that in the subject box, above.
Attached to the inside of the terminal box lid are two fused suppressors, there is no connection diagram.
1 Am I safe to insulation test at 500/1000v?
2 Semi restore the brush gear, the spring tension gear maybe weak etc?
3 Do I leave the com well alone or clean it with a fibre-glass stick while it's running?
4 Would anyone know if there is a connection diagram available, that includes the
suppression units?
5 I have some 24v and 50v incandescent lamps, low wattage, would they provided enough load to test the unit? In series and/or series/parallel configuration?
It's 55 years since I did this stuff at college, rusty isn't the word?!!
Thank you in advance for any help!

 

[TugboatEng]

You would have to wire pairs of 50v bulbs in series and then wire the pairs in parallel. It would take 55 pairs of bulbs to generate the load you want.

Now, an often forgotten fact is that incandescent bulbs have a tremendous amount of inrush current, 9x the bulb rating, when the bulb is switched on. This shouldn't be a problem if you're switching on pairs in smaller groups but bulk loading could cause problems.

 

[waross]

Does this produce AC or DC?
Dynamo implies Direct Current.
The difference between a typical DC motor and typical, conventional DC generator is only a few Volts or a few RPM.

Example:
Turn a DC machine with a constant speed prime mover.
With the shunt field excited, apply a voltage to the armature. Adjust the voltage until the armature current is zero.
Now increase the voltage slightly and the DC machine becomes a motor. trying to over-speed the prime mover. Decrease the voltage slightly and the DC machine becomes a generator, trying to push power into the voltage source.
Adjust the voltage back to zero armature current.
Now hold the voltage constant and reduce the speed. The DC machine becomes a motor trying to over-speed the prime mover.
Increase the speed, The DC machine becomes a generator, trying to push power into the voltage source.

Identify your windings and use a standard wiring diagram.
Note. The circuit from A1 to A2 will include the compensating pole as well as the armature circuit.
The commutating poles are shown in text book diagrams but are seldom shown on connection diagrams for actual machines.
When your connection diagram shows A1 and A2, the commutating poles will be included in the circuit even if thy are not specifically shown.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[davidbeach]

Pairs in series and then those pairs in parallel until you get to 55…?

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[waross]

Interesting calculation. 55 lamps arranged in pairs? 27.5 pairs? times ??? Watts per bulb = ......


--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[Hoxton123]

Crompton Parkinson was taken over by Hawker Siddeley in the late 1960's. After several changes of ownership, the brand remains active:

http://www.brookcrompton.com/about-us/

You could try them for support, but it may be too late for this legacy product.

I think that DC machines were manufactured at the main Chelmsford factory, which was closed shortly after the take over, as the product range complemented that of Hawker's existing Brush factory in Loughborough.

Brush were not interested in supporting the Chelmsford legacy products, and sold the spares etc side off to a company called Smith. I cannot find this company so it may also have disappeared.

Good luck, but your machine is probably over 50 years old!

 

[Steve C]

Hi gentlemen thanks for the replies, yes I hadn't thought the loading out at all, 'must engage brain before typing', I will try and source a wiring diagram and spend a little more time investigating the 'grime' scene. I'll also post the results WHEN we trial it!!
Confident or what??
Thanks again!

SteveC

 

[waross]

If you can get it up to speed, try exciting the shunt field with a 12 Volt battery.
Measure the output voltage of the armature. A ratio will suggest a field voltage for 100 Volts output.
Meggering:
I wouldn't go above 500 Volts.
I would use 250 Volts if possible.
I have seen serviceable brush-gear, even on new machines at around 50,000 Ohms.
Don't expect to see meg-Ohms on a circuit if the brush-gear is in the circuit.


--------------------
Ohm's law
Not just a good idea;
It's the LAW!