What is Mains Ripple Injection?
A mystery bunker item teardown turned out to be a very interesting and obscure bit of test kit.
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We have something like that here in Florida ( not like that Aussie country
) where my power provider Florida Power and Light shuts down high power energy devices like water heaters and air conditioners during high demand periods , for reduced prices on the kiilowatt hour. We have a control box that F.P.L shuts down high demand 240 volt appliances either by like what you show in this video with ripple injection or the 4G network
In Sydney, the 'zell' found your old fusebox is a throwback to when Prospect County Council monopolised the supply of electricity. The zells were supplied to PCC and installed in residential meter boxes along with two meters, a general rate and the off-peak rate which was activated by the zell, through a hard non fused hot water isolation switch which was separate to the one marked main switch(!), fed through a regular old ceramic fuse and then it went off toward your hot water tank.
When your hot water tank died, a new 315 litre tank would take up to 48 hours to supply hot water, so plumbers used to unceremoniously cut the county council security tags running through the screws on the zell and flick to switch to on so the tank would start heating immediately. The next off-peak signal cycle would cause the zell to just act as normal. From about '92? onwards the zell supplied was a new and improved model. With this one, you could flick the breaker switch inside the zell all you like but the thing would turn off again after about 20 minutes. Fuckers!
Commercial premises had a similar arrangement in that while there was no zell, there were separate meters for Process Heat. There were different rates offered and it was intended for kitchens with deep fryers and big ovens. Hand dryers in the dunnies were permitted also if I remember correctly.
The other annoyance with zells was if a lightning strike killed the zell, your tank could take a day or two before you realised the heater wasn't working. You'd ring your electrician, who would come out only to tell you the zell needs changing. So then, you'd have to contact the govt-run Prospect CC and ask them nicely if they could kindly replace the zell at their convenience any time in the following fortnight. Maddening. Some later HWT's had booster elements in the top connected to general rate, and when the zell quietly shit itself, your power bill skyrocketed.
Off peak signal injection has played havoc on audio equipment from the early '70s with early transistor amps and rudimentary power supplies. You'd hear that 1050hz sound all the time. The valve gear that I had didn't seem to pick up as much or maybe I didn't notice it.
This annoying signal still plagues Sydneysiders to this day as it causes LED downlights to 'dip' and speed controlled fan motors to be affected. Whilst I have systematically gone through my place and replaced or filtered audio gear that picks it up, my air-con fan sounds like darth vader at times during the night.
I saw a vid once of a car sized signal mechanical injector at a power plant. I'll see if I can find it.
I guess it can cause vibrations on electric motors.
The extra frequency could effect some not so well designed zero crossing detection used in some motor controls or clocks.
Some motors also directly can work like a speaker - so one might hear some of the frequencies.
I saw a vid once of a car sized signal mechanical injector at a power plant. I'll see if I can find it.
I believe I saw that one too. It is a multipole generator driven by a synchronous motor. The generator has many poles. to generate an output frequency several times that of the mains.
I began working on large UPS systems for a manufacturer in Melbourne 1987. About 6 months into the job I'd flown up to Brisbane to commission a 400 or 500 kVA unit. In those days commissioning could take a week or two with lots of 'on the fly' changes being made to the UPS. All the control boards were full of resistors on stands and I'd carry around a booklet with every 1/4 watt resistor value and spend a week or two taking measurements and changing resistors to suit local requirements etc.
I still vividly remember looking at the mains waveform when this weird ripple superimposed itself upon the 50 Hz. I did a WTF is that in response and very luckily had a senior engineer with me who casually leaned across, had a look, and told me it was just a Zellwegger tone. He then explained what it was for and all was right in the world. I took one look at Dave's box at the start of the video and knew exactly what it was going to be
Dave,
Interested in offloading this? I am developing a Decabit decoder, so this could be quite useful for testing.
Capturing this transmissions
is the perfect use case for puttinc to use the pass/fail waveform triggering feature of modern scopes
30kW 50 Hz motor injecting 1050 Hz ripple
30kW 50 Hz motor injecting 1050 Hz ripple
Got to love the data transmission at 0.1 Baud or something!
