aqrannes skrev:Efter at have spillet på den fine The Fisher de seneste 4 timer syntes jeg at transformatoren bliver lidt for varm. Jeg kan kun holde hånden på oversiden af den i +-5 sekunder. Er det normalt?
Kan det være en kombination af, at du føder den med lidt for høj spænding fra din step-down trafo og ikke mindst, at den nu arbejder med 50Hz i stedet for de 60Hz, den var designet til?
Fra Wikipedia:
Back in high school physics we observed magnetic flux lines traced by iron filings in a magnetic field. Says Steve, “An energized transformer is an electromagnet and therefore creates similar magnetic flux line patterns. When dealing with flux lines and transformers, two laws of physics are particularly significant:
1) Each magnetic material which could be used in a transformer’s core has a limit on how many flux lines it can handle
2) The lower the operating frequency the more flux lines that are generated. Operating a transformer at 50Hz generates 20% more flux lines than at 60Hz. As the number of flux lines approaches the magnetic material’s limit, the heat in both the transformer’s core and its coil wires increases, and under certain circumstances, unpredictably so. This can result in a transformer that exceeds safe temperature levels. Therefore, a transformer designed to run at 50Hz will simply run cooler at 60Hz. But one designed only for 60Hz may overheat if subjected to 50Hz.
“In order to accommodate 50Hz operation, the transformer must employ a magnetic core material that can handle the added flux lines. Such materials are readily available, but they are significantly more costly than the "normal" core materials. Using such high-grade core materials when they are not required results in transformers that are over-designed and probably overpriced.
“So, if a transformer will ever see 50Hz (for the European, South American, UK, Japanese, or other markets), the capability to do so must be designed in from the beginning. But if it will not see 50Hz, there is no sense in adding the unnecessary cost.”
Jeg synes, at dette forhold kan sagtens forklare den ophedede power-transformer, og hvis det forholder sig sådan, kan man ikke rigtig gøre noget ved det. Bortset selvfølgelig fra, at føde den med lavere drifts spænding fra en step-down transformer og acceptere, at forstærkeren så ikke kan leve 100% op til specificerede data. På et tidspunkt, bliver for lav glødespænding også et problem ift. den løsning.