Overhead Line Protection Cabinet

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The cabinet is designed for protecting 110kV overhead power lines. The AC circuits provide connection to secondary circuits of main current transformers with rated secondary current of 1A or 5A. The overhead line protection cabinet performs relay protection and automation functions for overhead and cable lines of specified voltage, as well as circuit breaker control automation. Specifically:

  • Provides protection against phase-to-ground faults;
  • Implements long-distance backup protection;
  • Performs three-stage automatic discharge during current overload (line thermal protection).

Additional functions of overhead line protection cabinets include:

  • Voltage disconnection during electrical equipment faults;
  • Line section isolation;
  • Protection of other designated elements.

The cabinets can detect abnormal conditions and faults, record oscillograms of deviating processes. Depending on protected objects or elements of the power supply system, the cabinet protection configuration may vary. 

Cabinet Components:

  • Current measurement circuits;
  • Voltage measurement circuits;
  • Protection input/output circuits;
  • Relay control circuits;
  • Lighting and power outlet circuits.
Technical characteristics:
 
Parameter Value
Measurement circuit current type (frequency) АС, 50Hz
Rated measurement current 5А
Rated voltage 100V
Protection rating (IP) IP31
Internal separation type Type 1
Functional block connection type  FFF
Nominal value of additional chains
Auxiliary circuits current type (frequency) АС, 50Hz
Rated auxiliary circuit current 16А
Rated auxiliary circuit voltage 220V
Nominal value of additional chains
 Operational power supply current type DC
Rated operational power voltage 220V
Connection protocol settings
Communication interface RS-485 (Digsi)
Communication protocol IEC 60870-5-103
General cabinet characteristics
Ambient temperature range (20 ± 5) °С
Relative humidity not more than 80 %

Cabinet design:

The cabinet features a grounded metal enclosure with two-sided access, a transparent front door, and a solid metal rear door. All metal components are corrosion-protected. Surfaces are coated with epoxy-polyester powder paint, and insulating materials are flame-retardant. For convenient external cable connections, the cabinet includes a base frame, grounding busbar, and cable tie-off rails.