BOLZAN IVANO (IT)
| DE8503677U1 | 1985-05-09 | |||
| GB863833A | 1961-03-29 |
| 1. | An electrical resistor characterised by comprising a metal armour surround (2) housing a dielectric support (6) on which at least two resistive wires (12) are wound insulated from each other and from the armour surround, said wires being connected at one end to separate terminals (8), at their opposite end they being connected to a common terminal (14). |
| 2. | A resistor as claimed in claim 1 , characterised in that the support is of cylindrical shape. |
| 3. | A resistor as claimed in claim 1 , characterised in that the support is covered with magnesium oxide. |
| 4. | A resistor as claimed in claim 1 , characterised in that the wires are wound spirally. |
| 5. | A resistor as claimed in claim 1 , characterised in that the terminals are inserted into the support. |
The present invention relates to an electrical resistor.
Electrical resistors are known consisting of a metal armour surround, filled with magnesium oxide, in which are inserted cylindrical supports of dielectric material, generally two or three in number, about which resistive wires are spirally wound, with their ends emerging from the armour surround.
These resistors are used to obtain different output powers, depending on the connections made between the ends of the resistive wires.
These known resistors suffer however from the drawback that if only one or two of their resistance portions are used, the heat is developed only in the region surrounding those resistance portions, hence creating surface temperature disuniformity.
This drawback is eliminated according to the invention by an electrical resistor as described in claim 1. A preferred embodiment of the present invention is described hereinafter with reference to the accompanying drawing, which shows a longitudinal section through a resistor according to the invention.
As can be seen from the figure, the resistor of the invention comprises substantially a metal armour surround 2 filled with magnesium oxide 4 and housing a cylindrical tube 6 of dielectric material.
Said cylindrical tube 6 is traversed longitudinally by three metal rods 8 which emerge at both ends 10, 10' of the tube.
Resistive wires 12 spirally wound equidistantly about the tube have their ends connected to the rod portions which emerge from the end 10, for example that to the left when observing the drawing, and are connected
together at their other end and to a further rod 14 also partially inserted into the cylindrical tube.
The resistor is used in the traditional manner by suitably connecting those rod ends 8 and 14 which emerge from the armour surround, to achieve greater or lesser power depending the connections made, but which in any event is developed along the entire length of the tube.
Next Patent: ARMOURED ELECTRICAL RESISTANCE ELEMENT