Abstract: An electrical insulator offering reduced sensitivity to pollution comprises a body of a glass or porcelain dielectric material with a semiconductor outside coating. This coating mainly consists of zinc oxide with at least one further metal oxide added to it to make its voltage-current characteristic non-linear, such that I=kV.sup..alpha. where I is current, V is voltage, k and .alpha. are coefficients, and the value of .alpha. is between 20 and 50. The coating is between 0.05 and 0.5 mm thick. The further metal oxide is advantageously selected from bismuth, manganese, cobalt, chromium and antimony oxides.

Abstract: The invention relates to electrical insulators having increased resistance to partial discharges and electrical equipment comprising such electrical insulators.These electrical insulators are formed of a macromolecular material in which is incorporated a chelate which is a derivative of an organic compound of general formula: ##STR1## wherein: R is CH.sub.2 COOM or --OH,M is Na or H,x is an integer from 1 to 4,n is an integer from 0 to 4,the metal chelate being present in the material in an amount sufficient for promoting the extinction of partial discharges, said amount not exceeding a value which would alter the physical properties of the insulator such as the volume resistivity thereof.

Abstract: The invention relates to electrical insulators having increased resistance to partial discharges and electrical equipment comprising such electrical insulators.These electrical insulators are formed of a macromolecular material in which is incorporated a chelate of general formula: ##STR1## wherein: R.sub.1, R.sub.2 and R.sub.3 each represent hydrogen or a alkyl, aryl, or cycloalkyl group or a heterocyclic group containing a sulphur, oxygen or nitrogen atom, whereby said group or heterocyclic group may be substituted by one or more halogen atoms;X and Y represent oxygen or sulphur;The total number of carbon atoms in the metal chelate is between 5 and 25;M.sup.n+ stands for a metal ion, andN is an integer from 1 to 4, this enolate or thioenolate being present in said insulating material in a sufficient amount for promoting extinction of partial discharges, said amount not exceeding a value which would substantially alter the physical properties of the insulator, such as its volume resistivity.

Abstract: The invention relates to a tactile pick-up for making contact with an object and emitting signals which are representative of the deformation caused by the object. The pick-up comprises a supple layer of variable electrical conductivity as a function of its state of compression, a matrix of measuring electrodes each connected to an output lead, and a large number of conducting elements connected to an electric source fixing their potential at a determined excitation value.