Silvercore Power Filters
How Do We Clean Our Electricity?
There are basically two options for this: either we produce the same clean electricity or we clean the existing one. Since I do not want to become the power plant operator, I have to clean the existing power.
A filter is needed. Not with a net filter module in the size of a matchbox, such filters are sufficient. The results are more or less intoxicating, basically the things limit the dynamics. Not a small toy, then, but something really official.
Stefan Götze and Christoph Kraus from Silvercore have found the solution in EMC measurement technology. There are so-called V-network replicas. These are used to measure the network noise coming from a device under test. For this purpose, the candidate must first of all be supplied with interference-free mains current, which the V-network replica supplies. It is basically a very good line filter with measuring connections.
The disadvantage of these commercially available network simulations is that they are specified in accordance with the standard only for a range of 9 kHz to 30 MHz. That's exactly what we were looking for, only much broader.
The Net Filter
On this basis, we have developed a device that has a 1GHz extended frequency range for audio and lab applications, with full attenuation of 40dB.
The filter is fed on the primary side by 3-phase three-phase current, all phases and neutral conductors pass through a separate filter consisting of air coils and capacitors. Of course, the earth PE is decoupled accordingly and also filtered. At the output there are then three sockets available which each 40dB attenuation to the network and have 80dB each other.
In order to avoid current limitation or saturation problems and thus the filter operates independently of the load, air coils with a very large conductor cross-section are used. The air coils are wound on specially turned POM tubes with 120mm diameter and 60cm length. Each of the coils is housed in a separate RF-tight enclosure. A large ferrite filter in the filter input effectively suppresses the power supply line in the high-frequency field.
The internal wiring is made throughout with 16 mm² cable. Accordingly, the internal resistance is lower than with a good 2m high-end power cord: we measure 30 milliohms. Compared to conventional filters, therefore, a limitation of the dynamics is not to be expected, despite significantly extended attenuation range.
Filter Effect
The results of the filter can be seen. The filter effect of our filter is at least 40dB. This is the red line on the screen. The filter works independently of load from 9kHz to 1GHz.
The filter results are respectable : 40 dB attenuation means that only 1% of the interference voltage or 0.1% of the interference power is allowed to pass through.
The pictures "Radio frequency interference in the network" and "Radio frequency interference eliminated" speak for themselves.
Without Compromises
If the filter on the net to unfold its full effect, and he does so by short-circuiting all disturbances to ground vehemently, it is usefully connected before the RCCB to the domestic power grid. For this we recommend a permanently installed box as we know it from the connection of a cooker in the kitchen. The filter is therefore equipped with three own residual current circuit breakers as well as screwed mains fuses and thus complies with all current regulations. Of course, the filter can be taken in case of prolonged absence with a powerful emergency stop switch from the network.
Since capturing of field-bound RF interference after the filter is unwanted, the stereo system is powered by shielded cables and own three power strips in which further ferrite filters are integrated against high frequency (mobile phone). Here we connect consumers, one for analog source devices such as turntables and pre-amplifiers, one for digital sources like CD players and one for the power amplifiers.
The filters are built on a customer-specific basis. Laboratory or living space. Hard on the net or transportable. Raw or with comfort.
Technical Specifications
- current carrying capacity 3 x 35A continuous operation, 3 x 50A peak power
- mains voltage input 3x230V AC + N + PE
- dimensions (w x h x d) 485 x 745 x 610 mm (without controls and connections)
- weight 102 kg
- connection cable 5 x 16 mm², C-Con
- outputs 3 x 1-phase PCE
- overvoltage protection, residual current circuit breaker after filtering, 3 mains fuses
- filter effect 9kHz-1GHz, better 40dB
- filtering separated 3 xAC, N and PE
