Zellweger off-peak
Encyclopedia
Zellweger is the brand-name of an electric switching device used to switch off-peak electrical loads, such as off-peak hot water, on and off. Power stations transmit a ripple
on the main transmission lines when off-peak rates start (often around 10 pm). This ripple noise is picked up by the Zellweger, which after a random delay turns the hot water heater on. The noise is often picked up by other equipment, especially audio amplifiers and stereos and the noise can cause problems with other electrical devices. Even some telephone lines can pick up the noise. The noise can be particularly obtrusive from some fluorescent light systems.
Newer electrical meters incorporate this technology into the meter. "Time of use" meters charge electricity to the current tariff within half an hour, giving customers incentive to run appliances such as dishwashers, pool pumps and clothes dryers during the night.
The random time delay in the Zellweger means that the power stations aren't hit with a huge demand when all the hot water systems turn on at the same time, rather the load is spread over a greater time period.
. Zellwegers were first introduced in Australia
in 1953, however were not compliant with modern harmonic disturbance standards. The second generation was introduced in the 1970s and was more reliable.
A variety of devices can still be seen across Australia.
In at least some parts of Sydney, the ripple frequency is 1050Hz. The signal usually consists of several bursts of a few seconds on and off, followed by a period of up to 50 seconds on. This is coded to affect only selected equipment. Occurrences are very frequent, sometimes several time an hour throughout the day, not just at evening and morning off-peak times.
See example capture by freeware Relisoft Frequency Analyser:
The bright line at 50Hz is the power frequency, followed by odd harmonics at 150Hz, 250Hz and so on. The ripple being turned on and off is clearly visible at 1050Hz.
Ripple (physics)
The most common meaning of ripple in electrical science is the small unwanted residual periodic variation of the direct current output of a power supply which has been derived from an alternating current source...
on the main transmission lines when off-peak rates start (often around 10 pm). This ripple noise is picked up by the Zellweger, which after a random delay turns the hot water heater on. The noise is often picked up by other equipment, especially audio amplifiers and stereos and the noise can cause problems with other electrical devices. Even some telephone lines can pick up the noise. The noise can be particularly obtrusive from some fluorescent light systems.
Newer electrical meters incorporate this technology into the meter. "Time of use" meters charge electricity to the current tariff within half an hour, giving customers incentive to run appliances such as dishwashers, pool pumps and clothes dryers during the night.
Impact
Power stations have plenty of unused capacity late at night but must keep running as they take days to shut down. Off-peak rates are used as an incentive for customers to use this surplus capacity and to reduce the amount of peak demand. This can produce cheaper power by delaying the need to build new power stations and reduce environmental impact.The random time delay in the Zellweger means that the power stations aren't hit with a huge demand when all the hot water systems turn on at the same time, rather the load is spread over a greater time period.
History in Australia
Originally time-clocks were used, however they can easily lose accurate time and are not easily adjusted for daylight saving timeDaylight saving time
Daylight saving time —also summer time in several countries including in British English and European official terminology —is the practice of temporarily advancing clocks during the summertime so that afternoons have more daylight and mornings have less...
. Zellwegers were first introduced in Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
in 1953, however were not compliant with modern harmonic disturbance standards. The second generation was introduced in the 1970s and was more reliable.
A variety of devices can still be seen across Australia.
In at least some parts of Sydney, the ripple frequency is 1050Hz. The signal usually consists of several bursts of a few seconds on and off, followed by a period of up to 50 seconds on. This is coded to affect only selected equipment. Occurrences are very frequent, sometimes several time an hour throughout the day, not just at evening and morning off-peak times.
See example capture by freeware Relisoft Frequency Analyser:
The bright line at 50Hz is the power frequency, followed by odd harmonics at 150Hz, 250Hz and so on. The ripple being turned on and off is clearly visible at 1050Hz.