A sensor system includes a sensor network comprising at least one optical fiber having one or more optical sensors. At least one of the optical sensors is arranged to sense vibration of an electrical device and to produce a time variation in light output in response to the vibration. A detector generates an electrical time domain signal in response to the time variation in light output. An analyzer acquires a snapshot frequency component signal which comprises one or more time varying signals of frequency components of the time domain signal over a data acquisition time period. The analyzer detects a condition of the electrical device based on the snapshot frequency component signal.

A sensor system includes a sensor network comprising at least one optical fiber having one or more optical sensors. At least one of the optical sensors is arranged to sense vibration of an electrical device and to produce a time variation in light output in response to the vibration. A detector generates an electrical time domain signal in response to the time variation in light output. An analyzer acquires a snapshot frequency component signal which comprises one or more time varying signals of frequency components of the time domain signal over a data acquisition time period. The analyzer detects a condition of the electrical device based on the snapshot frequency component signal.

The disclosure relates to a system for preventing gas bubbles in oil flow to enter a high-voltage device, which system is located in flow direction of the oil before the high-voltage device and comprises a gravitational gas bubble filter in which velocity of the oil flow is decreased by an enlargement of space for the oil flow and in which the gas bubbles in the oil are separated from the oil flow based on the effect of gravity. The invention also relates to a method for preventing gas bubbles in oil flow to enter a high-voltage device, in which method velocity of the oil flow is decreased by an enlargement of space for the oil flow and the gas bubbles of the oil flow are separated from the oil flow based on the effect of gravity.

The disclosure relates to a system for preventing gas bubbles in oil flow to enter a high-voltage device, which system is located in flow direction of the oil before the high-voltage device and comprises a gravitational gas bubble filter in which velocity of the oil flow is decreased by an enlargement of space for the oil flow and in which the gas bubbles in the oil are separated from the oil flow based on the effect of gravity. The invention also relates to a method for preventing gas bubbles in oil flow to enter a high-voltage device, in which method velocity of the oil flow is decreased by an enlargement of space for the oil flow and the gas bubbles of the oil flow are separated from the oil flow based on the effect of gravity.

A method of determining polymerisation of transformer insulation within a transformer. The method includes the steps of measuring a first and second moisture activity of oil in a transformer, and a first and second temperature of the transformer. The method further includes calculating the ratio of the gradients of the moisture equilibrium curves associated with the moisture activity and the temperature. The calculated ratio can then be used to characterise the polymerisation of the insulation and age of the transformer.

A method of determining polymerisation of transformer insulation within a transformer. The method includes the steps of measuring a first and second moisture activity of oil in a transformer, and a first and second temperature of the transformer. The method further includes calculating the ratio of the gradients of the moisture equilibrium curves associated with the moisture activity and the temperature. The calculated ratio can then be used to characterise the polymerisation of the insulation and age of the transformer.

A transformer includes an outer cabinet and an inner tank. The outer cabinet includes a base configured to be installed below ground level, a housing wall configured to be installed at least partially below ground level, and a sill coupled to the housing wall and configured to be installed above ground level. The sill includes a top access opening between an interior space of the outer cabinet and an exterior of the outer cabinet. The inner tank is disposed on the base at least partially below ground level and includes an active part including a transformer circuit. The inner tank includes a plurality of terminals electrically coupled to the active part, each terminal extending from the inner tank into the interior space of the outer cabinet along a respective terminal axis that passes through the top access opening at a respective upward angle with respect to ground level.

A transformer includes an outer cabinet and an inner tank. The outer cabinet includes a base configured to be installed below ground level, a housing wall configured to be installed at least partially below ground level, and a sill coupled to the housing wall and configured to be installed above ground level. The sill includes a top access opening between an interior space of the outer cabinet and an exterior of the outer cabinet. The inner tank is disposed on the base at least partially below ground level and includes an active part including a transformer circuit. The inner tank includes a plurality of terminals electrically coupled to the active part, each terminal extending from the inner tank into the interior space of the outer cabinet along a respective terminal axis that passes through the top access opening at a respective upward angle with respect to ground level.

An electromagnetic induction device includes: a main tank, a magnetic core arranged in the main tank, an On-Load Tap Changer, OLTC, comprising: an OLTC tank mounted to the main tank, a fine selector, a diverter switch, a change-over selector, and a customer interface; and a barrier separating the main tank from the OLTC tank, wherein the diverter switch and the change-over selector are arranged in the OLTC tank, and the fine selector and customer interface are arranged in the main tank, and wherein the barrier comprises a plurality of electrical connections configured to connect the diverter switch and the change-over selector to the fine selector.

The present invention relates to the use, for increasing the power of a transformer, of at least one dielectric fluid of general formula (1):

(A-X).sub.n-B  (1)

in which A and B, which are identical or different, represent, independently of each other, an optionally substituted aromatic ring, X represents a spacer group and n represents 0, 1, 2 or 3.
The invention also relates to a transformer containing at least one dielectric fluid of general formula (1).