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hometransformers › Toroidal


Toroidal transformers, Figure 1

General: We also supply a small range of toroidal transformers. These are more difficult to manufacture but more closely reach ideal transformer performance due to the lower leakage field and magnetising current required. These improvements are due purely to the geometry and physical characteristics of the construction.

Technical characteristics: These transformers are lower profile than the standard range we manufacture for a given VA rating. A thermal fuse (resettable or one-shot) can be fitted if required. They are supplied with a mounting bolt, two rubber insulators (one above and below) and one mounting plate per unit (See fig.1). The specifications are very similar to our standard range in all respects other than this. Typically toroidal transformers are supplied with flying leads (250mm). Multiple primaries and secondaries are possible.A Faraday shield is applied between the primary and the secondary (for safety and also to reduce inter-winding capacitance). These transformers meet thermal class B.

The core is made up from a continuous strip of grain oriented silicon steel (See area A- Fig 2). This means there are no air-gaps in the core leading to the improved performance as outlined above. Next comes the core insulation to hold the core in place and for safety (area B- Fig 2). Then the primary winding (area C- Fig. 2) The primary and secondary enamelled copper wire is typically Class F (155ºC) or Class H (180ºC). Next is a layer of insulation to meet safety standards (area D- Fig 2). Then the Faraday or earth screen (area E- Fig 2). Next is a layer of insulation and then the secondary winding (area F- Fig 2) and the outer insulation (area G- Fig 2). Finally sometimes a magnetic shield is fitted where a low magnetic radiation is required (area H- Fig 2). In this case a further layer of insulation is added after the magnetic shield. As with our other ranges of transformers the frequency default is 50/ 60Hz operation. Any primary and secondary voltages are available up to 700V. Multiple primaries and secondaries (all mutually galvanically isolated from one another) are available if required. We do not carry a standard range of voltages for this range.

This range is considered more or less a custom range of transformers. For information on typical dimensions for a given VA rating see Fig 3. Normally this range is supplied without an enclosure. These transformers can withstand up to 35ºC ambient and 106% input voltage continuously.

Standards: EN 61558.

Leadtimes; prices: The leadtimes for these transformers vary from 5 days to 6 weeks depending on quantity and complexity. Prices are available on application.

“Cut away”, Figure 2
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