To obtain a pressure tank that achieves a high manufacturing efficiency and does not hamper storage of an open/close portion such as a vacuum valve in a pressure tank. A pressure tank of the present invention includes: a tank body having at least one penetrating slit-shaped mortise and having a space formed inside the tank body; a reinforcing member having a tenon portion formed at an end thereof so as to be directed in one direction, and having an electric field relaxation portion on a side opposite to the tenon portion, the reinforcing member being attached to an inner wall surface of the tank body with the tenon portion inserted into the mortise; and a welding portion sealing and fixing the mortise and the tenon portion with no gap therebetween, the welding portion being formed by melting an end of the tenon portion from outside of the tank body.

A switchgear or control gear includes: at least one first compartment; at least one second compartment; a plurality of main switchgear or control gear components including a main busbar system, a three position linear or rotational movement disconnector, a circuit breaker, and at least a first part of an insulated cable connection; and a plurality of auxiliary switchgear or control gear components including a disconnector drive and a circuit breaker drive. The plurality of main switchgear or control gear components are housed in the at least one first compartment. The plurality of auxiliary switchgear or control gear components are housed in the at least one second compartment. When one or more of the plurality of main switchgear or control gear components is energized, the at least one first compartment is hermetically sealable or maintainable at an internal air pressure greater than ambient air pressure.

A switchgear or control gear includes: at least one first compartment; at least one second compartment; a plurality of main switchgear or control gear components including a main busbar system, a three position linear or rotational movement disconnector, a circuit breaker, and at least a first part of an insulated cable connection; and a plurality of auxiliary switchgear or control gear components including a disconnector drive and a circuit breaker drive. The plurality of main switchgear or control gear components are housed in the at least one first compartment. The plurality of auxiliary switchgear or control gear components are housed in the at least one second compartment. When one or more of the plurality of main switchgear or control gear components is energized, the at least one first compartment is hermetically sealable or maintainable at an internal air pressure greater than ambient air pressure.

A protection relay device includes a housing and a fuse unit. The fuse unit includes a connection conductor, an input conductor connected to the connection conductor and receiving an external power, a fuse connected to the connection conductor, and an external device connection conductor connected to the fuse on a side opposite to the input conductor, and to which an external device is connected. A short-circuit induction conductor is provided on at least one of the input conductor on a side opposite to the fuse and the flapper portion, the short-circuit induction conductor protruding toward the other of the input conductor and the flapper portion.

A system including a door, a fastener, and a fastener retaining assembly is provided. The fastener is extending at least partially through an aperture in the door. The fastener retaining assembly includes a bracket and a retainer washer. The fastener retaining assembly is attached to the door and retains the fastener to the door. The retainer washer is disposed around the fastener and disposed between the bracket and the door.

An inner compartment for medium voltage gas insulated switchgears includes: at least one inner compartment; and a housing. The inner compartment, or in case of several inner compartments, an inner of the inner compartment, or one of the inner compartments, is provided on an inner wall surface thereof at least partially with an insulating layer.

A method for monitoring switchgear, provided with a switching mechanism, including: monitoring an electric power supply signal to an electromagnetic actuator of the switching mechanism in order to detect the start of the supply of electric power to the actuator, monitoring an impact intensity measurement in the switchgear in order to detect the setting in motion of the switching mechanism, monitoring a parameter representative of the open or closed state of the switchgear in order to detect a change in state of the parameter, representative of an end of an opening or closing sequence of the switchgear.

The method further includes: calculating a time T.sub.ACT that has elapsed between the detection of the start of the supply of electric power to the actuator and the detection of the setting in motion of the switching mechanism of the switchgear, calculating a time T.sub.M that has elapsed between the setting in motion of the switching mechanism and the sequence end.

A method for monitoring switchgear, provided with a switching mechanism, including: monitoring an electric power supply signal to an electromagnetic actuator of the switching mechanism in order to detect the start of the supply of electric power to the actuator, monitoring an impact intensity measurement in the switchgear in order to detect the setting in motion of the switching mechanism, monitoring a parameter representative of the open or closed state of the switchgear in order to detect a change in state of the parameter, representative of an end of an opening or closing sequence of the switchgear.

The method further includes: calculating a time T.sub.ACT that has elapsed between the detection of the start of the supply of electric power to the actuator and the detection of the setting in motion of the switching mechanism of the switchgear, calculating a time T.sub.M that has elapsed between the setting in motion of the switching mechanism and the sequence end.

The present disclosure relates to an arc ventilation system of a distributing board, and more particularly, to an arc ventilation system of a distributing board to minimize an arc flowing forward to prevent damage. In the arc ventilation system of a distributing board in which a plurality of compartments are provided, a first compartment accommodating an electric power device which can be drawn in or out, among the plurality of compartments, comprises an arc blocking part blocking a space between the electric power device and the first compartment at an operation position of the electric power device.

At a connection portion between a common duct penetrating in an arrangement direction through switchgears arranged in the arrangement direction inside an electrical room, and an exhaust duct via which the common duct and outside of the electrical room communicate with each other, an end of the common duct is bent inward to form a first exhaust duct joining portion, and an end of the exhaust duct is bent outward to form a common duct joining portion. In a state in which an outer surface of the first exhaust duct joining portion and an inner surface of the common duct joining portion are in contact with each other, the first exhaust duct joining portion and the common duct joining portion are fastened and fixed by two or more pairs of bolts and welding nuts.