MV AC Switchgear

Types of MV switchgear installations

Metal-Enclosed Switchgear:

The Compartmental Type:

The complete installation is enclosed by earthed metal and hence sometimes is called the “package type.” The circuits are usually segregated into separate metal compartments, but the components of the circuit (bus bars, isolators CBs, etc.) are not necessarily in different compartments. The main insulation is air, and the CBs could be of any type. CBs are isolated either by withdrawal or by separate isolators.
Characteristics:

  • low space requirement
  • interlocking may be intrinsic
  • easy maintenance
  • factory built (site erection reduced)
  • less expensive than metal clad

Installation of this type is most common up to 36 kV.

Metal-Clad Type:

In this form of metalen closed switchgear, separate components are in earthed metal compartments. The insulation may be air or SF6. The CBs may be of the oil, vacuum, or gas blast type.
Characteristics:

  • Minimum space
  • Intrinsic interlocking, giving high degree of safety
  • Factory built
  • Expensive

In photo shown a dimensional difference between metal enclosure switchgear(left)(1404-1778 mm depth) and metal clad switchgear(right)(2438mm depth) manufacture by EATON company by vacuum CB.

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