The present invention refers to HV apparatus, in particular a HV dry current transformer, insulated with an insulating gel, or a voltage transformer, insulated with an insulating gel. The dry HV current transformer comprises at least two electrically conductive elements i.e. a head transformer cover, a head housing base, a core casing and a primary conductor. In the dry HV current transformer at least one of the electrically conductive elements has a coating made of solid insulating material separating the surface of the conductive elements from the insulating gel and adapted for limiting the electron emission from the conductive elements into the insulating gel. The voltage transformer comprises a bottom external housing, a bottom support flange, a core. In the voltage transformer at least one of the electrically conductive elements has a coating made of solid insulating material separating the surface of the conductive elements from the insulating gel and adapted for limiting the electron emission from the conductive elements into the insulating gel.

The present disclosure relates to a transformer. According to an aspect of the present disclosure, a transformer includes a case; a winding portion and an iron core portion, provided in the case; an insulating fluid provided in the case; and a reinforcing portion provided outside the case, and surrounding the case, wherein the reinforcing portion is made of a second material having a yield strength higher than a yield strength of a first material constituting the case, to pressurize the case and prevent expansion of the case.

The present invention relates to an On-Load Tap Changer (OLTC) for connection to a regulating winding of a transformer, the regulating winding enclosed in a transformer tank, wherein the transformer tank includes insulating liquid, the OLTC comprising: a switching device including: a main contact, and a resistor contact, wherein the main contact and the resistor contact are configured to be arranged directly in the insulating liquid and that they are configured to be physically separated from the insulating liquid, and wherein the main contact is enclosed in a main contact enclosure and the resistor contact is enclosed in a resistor contact enclosure. The present invention further relates to a transformer comprising the OLTC as disclosed herein.

An instrument transformer of a type designed for using an insulation medium containing SF.sub.6, said instrument transformer including a housing enclosing an insulation space and further including an electrical active part arranged in the insulation space, said insulation space containing a dielectric insulation medium. The instrument transformer is characterized in that the dielectric insulation medium contains a gaseous mixture including from 3 to 5 mol-% of heptafluoroisobutyronitrile, from 4 to 11 mol-% of oxygen (O.sub.2) and from 84 to 93 mol-% of nitrogen (N.sub.2).

A high-voltage transducer includes a housing, which spatially encloses at least one electrical measuring device and an insulating gas. The insulating gas is clean air, with which electrical insulation in the housing of the high-voltage transducer is carried out. A method for measuring with the high-voltage transducer is also provided.

An embodiment of the present invention relates to an enclosure for a voltage transformer, including a shell. The shell is provided with a plurality of packaging spaces for packaging bodies of the voltage transformer. Each of the packaging spaces is provided with a closed end and a sealed end, and every two adjacent packaging spaces are in communication with each other. In the enclosure for a voltage transformer of an embodiment of the present invention, the size of the enclosure for a voltage transformer along an arrangement direction is reduced, as a result of which, the entire enclosure for a voltage transformer has a compact structure and a small occupied space. An embodiment of the present invention further relates to a voltage transformer including the above-mentioned enclosure for a voltage transformer.

Methods and compositions for the production of dielectric fluids from lipids produced by microorganisms are provided, including oil-bearing microorganisms and methods of low cost cultivation of such microorganisms. Microalgal cells containing exogenous genes encoding, for example, a sucrose transporter, a sucrose invertase, a fructokinase, a polysaccharide-degrading enzyme, a lipid pathway modification enzyme, a fatty acyl-ACP thioesterase, a desaturase, a fatty acyl-CoA/aldehyde reductase, and/or an acyl carrier protein are useful in manufacturing dielectric fluids.

A temperature estimation method estimating a temperature of a heat generating site in an oil-immersed electric appliance immersed in insulating oil, the insulating oil being silicone oil or ester oil. The temperature estimation method includes measuring concentrations of two types of thermal decomposition products in the insulating oil and calculating a temperature of the heat generating site in the oil-immersed electric appliance based on a concentration ratio between the two types of thermal decomposition products and a relational expression between the temperature of the heat generating site and the concentration ratio prepared in advance. When the silicone oil is adopted as the insulating oil, at least one of the two types of thermal decomposition products is straight-chain siloxane, alcohol containing silicon, or benzene. When the ester oil is adopted as the insulating oil, the two types of thermal decomposition products are fatty acids.

A three-phase transformer according to an embodiment includes a first plate iron core and a second plate iron core disposed opposite each other; a plurality of columnar iron cores disposed between the first plate iron core and the second plate iron core so as to be connected to the first plate iron core or the second plate iron core, the number of the columnar iron cores being an integer multiple of 3, the columnar iron cores being disposed rotation-symmetrically with respect to an axis equidistant from central axes of the columnar iron cores; and coils including a plurality of primary coils and a plurality of secondary coils, the number of the primary coils being an integer multiple of 3, the number of the secondary coils being an integer multiple of 3, the primary coils and the secondary coils being wound on the individual columnar iron cores.

The present disclosure relates to a transformer system comprising a power transformer including a metal tank filled with an electrically insulating liquid, and a wireless sensor arrangement submerged in the insulating liquid within the tank. The sensor arrangement includes a radio transmitter for wirelessly transmitting sensor readings to the outside of the transformer through an opening in the tank, said opening being provided with a liquid-tight seal comprising a solid insulator for preventing leakage from the tank of the insulating liquid and wherein the radio transmitter is configured for transmitting the sensor readings using a carrier frequency within the range of from 100 kHz to 1 MHz.