Lucien's most challenging picture puzzle yet... what does this box do?

[Lucien Nunes]

You've seen some curious stuff in my vintage picture puzzles before but what can you make of this black box? I want to know not only what's inside but also its main electrical specifications; there are two in particular for which I need the actual figures.

There will be a few picture clues to help you along...

 

[Squid]

Its the place where they keep the skeletons in Blairs closet safe.........

 

[Percyprod]

Obviously something to do with space travel, 13 amp fir english space ships, 15amp for Welsh ones, as used by Morgan the Moon, (see Max Boyce).

 

[marconi]

Is the plate telling us:

1. At a voltage of 50V and rpm of 555, the current flowing is zero (ie no load) and no power is transferred from input to output.
2. At 275V and rpm of 530, the current drawn is 160A and the power transfer from input to output is 44kW (=275 x 160). These being maximum values for Voltage (speed) and Current(torque) for peak power transfer or to avoid overheating.

and noting that a 12 pole ac machine at 50Hz has a synchronous speed of 500rpm -

So,

3. Is this the plate on an electromagnetic brake or torque converter? An electromechanical impedance matcher?
4. A way of supplying power to the mains from an alternator without the need to synchronise the two supplies? Slip between input and output coils deals with difference in voltage, waveform, phase angle and frequency?

 

[ackbarthestar]

Telemetry closed loop receiver/transmitter to control water pressure.

 

[JK-Electrical]

Is it the cube of the Illuminati?

 

[Lucien Nunes]

You're overcomplicating things. Nessie lives in the loch. The water flows through the big pipe and turns the turbine that drives the generator. The plate is on the generator. What comes out doesn't look like Nessie. It's...

 

[marconi]

...uous cur... and I said alternator (=ac) and you said generator(=ac or dc).....and a kW rating rather than kVA. So continuous (aka direct) current hydro-electricity which is not like Nessie.

So as someone suggested earlier is there some dc to ac conversion equipment? Or does the house have two supplies one mains ac to the 13A sockets and the other h-e dc to the 15A? Or the 13A are fed by inverted h-e dc? I tend to think the latter if the installation is remote enough to still use only h-e which has been 'well maintained and strategically updated' over the years.

 

[marconi]

Still no closer to what the box is for. A guess - something to regulate the speed of the generator and control its excitation to stabilise the ac and dc voltage of the installation. So it might contain a rectifier and smoothing capacitor and an electro-mechanical contraption or electronic circuit to provide a reference dc voltage? You said there were two boxes separated by some distance. Perhaps then they are complementary in function - having derived a dc control signal it is converted to a higher voltage ac at the installation for transmission over some distance to minimise the effect of volt drop and then converted back to dc at the generator. No doubt over-complicating matters again.

 

[Richard Burns]

You're overcomplicating things. Nessie lives in the loch. The water flows through the big pipe and turns the turbine that drives the generator. The plate is on the generator. What comes out doesn't look like Nessie. It's...

Continuous current i.e. DC
But Marconi already said that,slow!

 

[Lucien Nunes]

In post #62 he was still considering that the generator produced 50Hz. We had to get the DC thing straightened out because even after 'inverter' surfaced in post 47, transformers re-appeared.

The original installation from the early 1930s was DC hydro only. Everything in the house was electric, even the water heating, as the energy cost was only the upkeep of the plant. Most appliances in those days were available for DC supplies, but increasingly there were newer and better ones for AC, so some means of providing AC was needed. This was installed, but for efficiency and to avoid having the AC running 24/7, heating, cooking and lighting load and appliances with universal motors such as vacuum cleaners remained on the DC, while the AC was reserved for appliances that needed it.

In time, the Grid arrived, and with it frequency-accurate 50Hz. This would be better for things like record players and allow the use of synchronous clocks, for which the locally produced AC would not be adequate. But it was not free, like the DC, thus the double wiring system remained. 13A outlets for AC, 15A for DC.

As Marconi has pointed out, the wooden cabinet visible in post #1 is a fridge. You would expect the owners of a house with its own 44kW hydro plant to be able to afford a big fridge, at a time when most people did not have a fridge at all. What remains for you to solve is why the box, which is connected with the fridge, was needed in the first place, and why it remained in service even after the Grid connection was made.

The pick-up truck isn't old, Marconi, but it's very big. The flasher is electronic and has ten pins due to its origin. Think of Ami vs. Bal-Ami. Osaka vs. Tokyo. Yellow vs. Black.

The box contains a ...... with an output rated at .....

Incidentally, the 44kW 240V generator is some distance from the house, and I believe the figures on the rating plate indicate that it inherently compensates for the feeder voltage drop by over-compounding. I'll return to this subject later.

 

[marconi]

The reference and order of the couplets BAL AMI- AMI, Tokyo-Osaka hint at a change of frequency from 50 to 60Hz.

Regarding the colours, yellow (from old Red Yellow Blue) and black (from new Brown, Black, Grey) hint at the second line/phase colour or 3 phase system.

The 10 pin flasher hints I think at something particular to the brand or nationality of automotive electrical parts which stumps me. Maybe 10 pins are only used in 24V dc systems only? I take a punt that the 10 pin flasher is used to generate a 60Hz square wave.

The 60Hz square wave is used in the box to modulate/chop the 240V dc from the h-e supply. From a 240V dc input a 60Hz chopped bipolar dc output is produced (square wave -120 - 0 - +120V)
which is filtered to produce a rough 60Hz 120V sine wave to power the US made fridge compressor ac motor. The box is a frequency changer. The motor is 3 phase so the box also generates a phantom 3rd phase using a Steimetz circuit.

 

[w0z]

the box contains a....

is the word Georator?

 

[Lucien Nunes]

We're getting painfully close so let's wrap it up. Marconi has nearly hit a number of nails on the head but we've not got the right words yet.

60Hz is the theme...

Ami Jukebox - US-made, 60Hz. Bal-Ami - UK made version, 50Hz.
Osaka - Western section of Japan's power grid, originally equipped with General Electric plant, 60Hz. Tokyo, Eastern section equipped by Siemens - 50Hz.
Yellow - NYC cabs, Black - London cabs.
Pickup truck flasher unit - even here Marconi was so close; yes it's to do with territory, it's a US spec GMC Sierra with both traditional American stop/turn and separate turn signals, as it has a towbar, so it has a very complicated flasher unit with lots of outputs.

What I have been driving at is that the fridge chiller unit was American, and thus 60Hz. When that fridge was made, America was much more advanced in terms of commercial refrigeration systems and the main manufacturers of such units were the other side of the pond. It was not uncommon to see US-made units fitted into UK-built cabinets, as in this case.

The house supply was DC, and there was a device for converting some of that into AC as I mentioned above, but that was 50Hz for UK-made AC appliances. The fridge, with its US-made chiller, required 60Hz, for which a separate unit was provided drawing from the house DC. So it was not a frequency changer, as suggested before, but a maker of 60Hz, 115V AC from DC. The sensor connected to the box was of course the thermostat, so that it would start and stop as the compressor was needed, instead of running idle whenever the compressor was not running.

And what, in those days, was the standard way to make AC from DC?

R... C...

Come on someone, then I can post some pics of it...

 

[freddo]

Rotary Converter?

 

[Lucien Nunes]

Yeehaa!

It's a rotary converter taking in 240V DC from the hydro supply, and giving out 115V 60Hz AC for the fridge's US-made chiller. Pics follow...