However, for voltages up to 220 kV, horizontal-rotating type disconnectors must be used. They are relevant for our country. Semi- and pantograph high-voltage disconnectors save space in outdoor switchyards and are usually used at high voltages up to 330 kV.
When designing a switchgear, space saving is very important. This issue is particularly acute in urban environments. The size of the disconnector affects the area of the switchgear: the higher the voltage class, the larger the area. Knife-type disconnectors have the smallest space between phases, but they have their drawbacks, such as overall height and difficult operation under icing conditions. In the latter case, the design becomes more complicated.
Horizontal-rotating type disconnectors have more space between poles, but they do not have the drawbacks of knife-type disconnectors. Their popularity in the domestic market is ensured due to the simplicity and reliability of the design. For higher voltages up to 330-750 kV, pantograph type disconnectors are usually used. This is done to maximize space reduction.
What to consider when choosing this device?
There are several requirements that these devices of all types must meet:
• Insulating structures must be arranged so that any current leakage goes to ground, but never between poles or pole terminals.
• Under any operating conditions, disconnectors must switch on and off clearly.
• There must be no unintentional disconnection of the disconnector.
• Mechanical wear resistance must be as high as possible.
• Standardization of electrodynamic and thermal resistance must be easily carried out under short-circuit currents.
• Long-term current flow through the current-carrying circuit must be ensured without any overheating of the contacts.
• The strength of the visible break in the electrical circuit, which occurs in air, must correspond to the impulse voltage at its maximum.
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