110 volts

[CHJ]

The higher frequencies could be found in older radar systems and the like, the point being that transformers increase in efficiency the higher the frequency so can be considerably smaller and lighter.

The Valiant Electrics were based on 112 volt direct current generators and backup batteries were a bank of 24 V and 96 V batteries, you did not want to short that to deck with your spanner very often. Or your gold signet ring as one of my co-workers did.

 

[AES]

CHJ:

Higher frequencies also make coils on motors, etc, more efficient, therefore lighter & smaller.

But 112V DC! Crikey! How many genys, 1 per engine?

The last DC-only aeroplane I had anything to do with was the Fokker F27 Friendship (though as later avionics such as basic Flight Directors and Smiths Autopilots came along they did also have a DC-driven inverter as an option). F27s also had a drive shaft with a Hardy-Spiced UJ (like on a car) coming out of the the engine to drive the big Roots blower for Cabin Conditioning, Nose Wheel Steering, Brakes, & U/C retraction (no hydraulics on F27s).

Anyway enough of this thread drift ;-)

Cheers
AES

But just 1 P.S. What happened to the signet ring? ;-)
(We were always strictly "encouraged" to remove jewelery, etc, plus loose articles before starting a job. I don't work myself now but do inspect and still always remove rings, my watch, etc, etc, before going into tight spaxces like the FWD Avionics Bay on B737s and A320s. Old habits die hard).

 

[CHJ]

How many genys, 1 per engine

Yes and they were some big brutes.

But just 1 P.S. What happened to the signet ring? .

It was a mess, but not as bad as the cooked finger, he was fortunate because the shock cramped his arm and broke the arc before it removed the finger.

Smiths Autopilots

Oh the hours flying around south wales sat on the inside of a freight hold door trying to trim the sep2 to match the airframe and minimise drift to meet project needs.

 

[AES]

Yeah, bloody stone age awful things - in Viscounts and 748s too.

Yup "those were the days".

AES

 

[CHJ]

Some years later in prettier colours.
http://www.flickr.com/photos/emdjt42/8429666531/lightbox/

and its Mate:-

 

[Phil Pascoe]

I was trying to justify buying a 110v creusen grinder on evilbay, but I missed it by £2 anyway.
Many thanks to all who replied.
Phil.

 

[AES]

Nice pix CHJ, thanks for posting (but what's that big bulge under the belly - you blokes at Boscombe Down & Farnborough got up to all sorts of stunts).

(Sorry for the thread drift Phil!)

AES

 

[RossJarvis]

Nice pix CHJ, thanks for posting (but what's that big bulge under the belly - you blokes at Boscombe Down & Farnborough got up to all sorts of stunts).

(Sorry for the thread drift Phil!)

AES

That's where they keep the beer and sandwiches :shock:

 

[CHJ]

They were in RAE colours in the pics, but they originated at RRE and the various appendages are associated with various radar and associated systems trials and developments from that time that eventually made their way into later front line systems.
If you read the opening paras of the above link, I was fortunate enough to be involved at the working end of most of those technologies from the late 50's to the mid 80's. made for a very satisfying work experience.

 

[AES]

Thanks for that link CHJ. As you say, interesting.

AES

 

[John Brown]

i have had lots of electric shocks the worst was 12v

Really? How did you manage that? You must have an extremely low resistance.

 

[wizard]

Its nothing to do with volts its amps

 

[John Brown]

Indeed, but there is a well understood(since 1827) linear relationship between volts and amps. I am genuinely interested to know how you managed to experience a bad shock from 12V.

 

[wizard]

Testing a starter motor of an MGB not sure what i did wrong done it loads of times before and i will never do it again. I often work on things that are 240v sometimes get a nasty kick if i forget to turn them off but never as bad as the 12v

 

[Racers]

Sounds like back EMF from the magnetic field collapsing, much more than 12V!

Pete

 

[John Brown]

That's another thing entirely. The collapse of the magentic field in the motor generates a brief spike that is a lot higher in voltage than 12V.

 

[Racers]

Its how the spark for your spark plugs is generated.

Pete

 

[heimlaga]

In Finland all hand held power tools used on site are 230 volt single phase. Many of the more stationary machines like table saws and concrete mixers use 400 volt 3 phase. In later years the construction sites has been flooded by cheap single phase table saws and concrete mixers but the general consensus among most workers who have ever used proper 3 phase machines is that the single phase ones are just toys and not fit for professional everyday use.
I have notised that single phase machines generally have much less power in them. As all the load is on one phase they have to put in smaller motors in order to not exceed the capacity of the normal 10 ampere or 16 ampere lines and fuses. Furthermore they have much less torque for the same power rating.

Actually there are a few hardy souls who still use American 110 volt tools coupled to those old 110 volt generator sets that were sold off by the US army after the invasion of Germany but there are very few of them left......fortunately.......

 

[Tony Spear]

Back in the late 90's I was carrying out some "remedial" (i.e. they'd cocked up the original installation) work on some vallve actuators in a pumping station near Lagos.

The plant had a step down transformer from ?? to 3.3 kV, which powered the main pumps and then a transformer to 415 volts with the required tappings to give 240 volts single phase for instrumentation and power for various things around the site (including the actuators I was working on).

Anyway, having isolated all the single phase stuff, there was I doing me bits and pieces in the main pump room, when there was the most almight great BANG
from the control room! Naturally, we all rushed to the control room to see what had happened, where we found one of the Client's Electrical "Engineers" up against the wall, several feet away from the motor control centre shaking like god knows what, eyes wide open with shock and his overalls gently smouldering! I don't suppose he ever tried to work on a live MCC ever again! :shock: