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       Ripple Control
 - Definition
 - First Experiments
 - Demystifying DECABIT
 - Analog filtering problems
 - Digital filtering method
 - Mathematical Analysis
 - Implementation on 
   PIC16F874

 
   A peek inside real
   receivers out there

 
- Zellweger (Enermer) RM3+
 - SIEMENS 7RR611
    (designed in RSA)
 - Zellweger Uster ZE 22/1

   
Reference Material
 
- Comprehensive listing

ELECTRONICS AND DEMAND MANAGEMENT BY POWER UTILITIES
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Ripple Control

Q: What is "ripple control"
A: Ripple control is a means whereby the local power authorities are able to temporarily turn off large electrical loads in peoples' homes to limit the impact of peak demand for electricity.


The local council is usually subject to steep rates for peak demand (peak means higher than usual) by ESKOM. Therefore in peak periods, such as when people get home from work to cook food, the local council will send commands to turn off the largest load in the home-
the water heater or "geyser" to reduce peak demand for electricity.
Then when peak demand subsides, normal operation is restored.

An example of a modern ripple receiver installed in homes.


My interest to this was drawn when in 1993 we moved into a different area. I noticed the house was fitted with a Zellweger Uster receiver circa 1975. I opened it to discover it was an electromechanical device with passive components and a resonant circuit that was tuned to 1050Hz. A very large paper capacitor and a very unusual ferrite transformer design on a base PC board to detect the tone and generate a signal upon its reception. The tone would start the mechanical timer, which was then held running by a latch contact. When the timer went past 360 degrees, the contact dropped out and the timer stopped (the transmission was also complete at this point) The pulse pattern incoming would then be matched upon output of this mechanical timer and if a match was detected it would activate the change-over relay contact, also a mechanical toggle design with a bakelite flag. The mechanical timer had a ratchet and pawl on a dial, the dial could be turned to select a number. I found out later they were channel numbers, 22 in all.

I very soon realized that other stuff is also being controlled this way and were on a different channel because, without fail, each time the streetlights came on, a transmission was always in progress (audible as 1kHz 

buzz in sympathy with the data on the line which I could hear when the streetlights came on). This audible buzz was also, and still is, a nuisance factor on audio equipment. Sensitive unbalanced audio inputs pick the signalling up easily.

Electromechanical receiver type ZE-22 circa 1971 installed in almost all homes in Roodepoort, Johannesburg, and Pretoria. Made by Zellweger Uster (now Enermet).

A WORD OF WARNING TO THOSE WHO HAVE THE BLACK RECEIVER SHOWN ABOVE AND ARE CONTEPLATING DISASSEMBLING IT OR OPENING IT...

The ZE-22 receiver (shown above) is classified as 
NUCLEAR WASTE. The equipment contains a  glass tube, that contains a pellet composed of radium and thorium. DO NOT CRACK OR BREAK the glass glow tube within. The function of this component is to limit the output of the ripple transformer, which, under certain conditions could reach insanely high voltages, the glow tube thus acts as a VS valve to protect the solenoid winding (remember, this receiver was made in a time when tubes (valves) were still being used in consumer electronics)

 I DO NOT accept any responsibility for your failure to heed this warning!!! 

Neither ESKOM or anyone else I know is aware of this little fact, and considering that ESKOM has mandated ripple receiver installations in ALL homes in SA, I presume this means replacement of the old with new.
See http://en.wikipedia.org/wiki/Zellweger_off-peak

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