The disclosure relates to a method for monitoring a vacuum on-load tap changer including determining a total main vacuum interrupter opening time as a time elapsed between a first point in time and a second point in time, a total resistor vacuum interrupter opening time as a time elapsed between the third point in time and the fourth point in time, a circulating current time as a time elapsed between the second point in time and the third point in time, and/or a switch time as the sum of the total main vacuum interrupter opening time, the total resistor vacuum interrupter opening time and the circulating current time.

A switch unit for switching over an onload tap changer. The switch unit has an on-load tap changer with an actuating shaft that actuates a switch; and a drive system with a motor. The drive system is mechanically coupled to and configured to actuate the on-load tap changer. The drive system is configured such that, when the on-load tap changer is actuated, the drive system uses the actuating shaft as a store for kinetic energy in such a way that the actuating shaft is accelerated and the switch is actuated by the kinetic energy from the actuating shaft and additional energy provided by the motor.

An on-load tap-changer includes: a tap-changer body and a driving mechanism fixed on the tap-changer body. The tap-changer body includes a housing, multiple insulation fixing plates, multiple turntables, each of which includes a sheave and a cam plate, the cam plate of which is rotatably connected to the insulation fixing plate, and the sheave of which is connected to the driving mechanism, multiple vacuum tubes fixed on the multiple insulation fixing plates, and multiple transmission mechanisms, each of which includes a lifting lever and a reverse spring. When the driving mechanism drives the sheave to regulate voltage, the cam plate is synchronously driven to rotate, and then the vacuum tube is driven by the lifting lever and the reverse spring to achieve on/off arc extinction, thereby achieving on-load voltage regulation.

A dropout recloser is capable of in accordance with its operating programming after a predetermined number of fault interrupting operations, e.g., 1, 2, 3 or more but typically 3, to drop out of a cutout and hang freely in a hinge contact of the cutout providing sectionalization with an observable visible gap. The recloser includes fault interrupting and reclosing components, a drop out mechanism and a controller. The drop out mechanism may include a bi-stable actuator to affect fault interrupting operation and dropout operation. The device may include motion limiting structures. The recloser may have a number of operating modes or sequences.

A vacuum interrupter for an on-load tap changer comprising a cylindrical housing arranged on an axis including a wall enclosing a hermetically sealed inner volume and a ceramic bottom part extending perpendicularly to the axis, the wall comprising a first optical interface between the inner volume and an outer environment, the first optical interface being configured to be transparent to at least one optical wavelength, the inner volume comprising an optical guide open to an environment of the inner volume, a switch coaxially arranged with the housing on the axis within the inner volume of the housing, the vacuum interrupter further comprising a shield element coaxially arranged with the switch, characterised in that the optical guide is arranged recessed in relation to an inner surface of the ceramic bottom part of the wall and in that the shield element is arranged between the switch and the optical guide.