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The minimum clearance required between the live conductors and maintenance operator is called
Ground clearance
Phase clearance
Sectional clearance
None of above
Sectional clearance
Sectional clearance is the minimum safety distance provided in a substation between live conductors and the ground or structures where maintenance personnel may be working. This clearance ensures that a person does not experience an electric discharge or flashover while performing routine maintenance or inspection tasks.
Sectional clearance is the minimum safety distance provided in a substation between live conductors and the ground or structures where maintenance personnel may be working. This clearance ensures that a person does not experience an electric discharge or flashover while performing routine maintenance or inspection tasks.
dminтАЛтИЭV
E=dVтАЛ
The principle relies on the Dielectric Strength of air. Under normal operating voltages, air acts as an insulator. If the physical distance between a live part and a person is reduced below the sectional clearance, the electric field intensity can exceed the breakdown strength of air (EbreakdownтАЛтЙИ30kV/cm), leading to an arc or flashover.
Sectional clearance is specific to substation layout and safety codes (IS 3072).
It depends on the nominal system voltage level.
It differs from ground clearance, which is the height of the lowest conductor from the ground level.
Safety is maintained by ensuring d>dminтАЛ where V is the phase-to-ground voltage.
Prevents accidental electrocution during maintenance.
Ensures compliance with electrical safety standards (e.g., CEA regulations in India).
Higher clearance requirements increase the physical footprint of the substation.
Increased land costs for larger installations.
High Voltage Substations (HV and EHV)
Switchyards
Power Transformers maintenance zones
For a 33 kV substation, the minimum sectional clearance is typically defined to be around 2.8 meters.
Ground clearance refers to the height of the conductor from the ground to prevent contact with passersby, whereas sectional clearance is specifically for operators within the substation.
Phase clearance refers to the distance between two phases of the conductors.
C is correct тАФ Sectional clearance is the vital safety gap required between energized equipment and maintenance staff to prevent flashover.
Always remember: 'Sectional' is for the person (operator), 'Phase' is for the conductors, and 'Ground' is for vertical clearance above terrain.