Earthing Switch MJN15-24

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Description

 

MJN15-24 — Indoor earthing switch (earthing switch) with insulators, designed to operate as a part of switchgear cabinets in three-phase alternating current networks with a frequency of 50 Hz, rated voltage 20 kV, with an insulated or grounded neutral arcing reactor or resistor, designed to visually separate the electrical section chains for the period of revision or repair of equipment.

The earthing switch is equipped with a spring drive, which ensures the movement of grounding knives at a speed independent of the speed of the operator switching.

 

Rated voltage, kV: 20

Maximum working voltage, kV: 24

Interfacial distance, mm: 210, 230, 250, 275

 

For visual inspection, the earthing switch is equipped with a position indicator, and the earthing switch drive system is equipped with a contact block for using the corresponding signals in the secondary signaling and control circuits. The drive system provides the necessary locks for using the ground electrode in the switchgear.

To create safe working conditions and to separate from live parts of electrical equipment, the MJN15-24 design provides for the use of two types of drives: motorized or manual, equipped with a blocking system that excludes the supply of voltage to the high-voltage equipment introduced for repair.

MJN15-24 is used to safely ground electrical equipment during repairs and maintenance.

 

Advantages of MJN15-24:

1. Security

The speed of the instantaneous mechanism is independent of the operator. Ability to turn on short circuit current.

2. Installation flexibility

The moving parts of the earthing switch are supplied assembled, and the response stationary parts are ready for installation. The pole distance can vary to install an earthing switch in the switchgear or separately. A manual drive or a motor drive may be used.

3. Compact

Compact design with minimal footprint

Parameters

 

Operating Conditions of MJN15-24:

  1. Altitude: up to 1000 m.
  2. Ambient temperature: from -25 C to + 40°C.
  3. Humidity: the average value of relative humidity during the day is not more than 95%; the average value of relative humidity during the month is not more than 90%.
  4. Seismic resistance up to 8 points.
  5. Environment is not explosive, does not contain dust, aggressive gases and vapors in concentrations that destroy metal and insulation.
  6. Lifetime – 25-30 years.
  7. Warranty period from the date of commissioning — 2 years.

The earthing switch complies with the national standard GB1985 (Disconnector and earthing switch AC for high voltage) and the international standard IEC60129.

 

Parameters of MJN15-24:


No.
Measurement Unit Data
1 Rated voltage kV 24
2 Rated short-time withstand current kA 31.5
3 Rated Short Circuit Duration 4
4 Rated peak withstand current kA 80
5 Rated short circuit current kA 80
6 The distance between the centers of the poles mm 210, 230, 250, 275
7 Nominal kV кВ 65
Rated lightning impulse withstand voltage (peak value) 125

Solutions

 

Solutions and Applications of Medium Voltage Earthing Switches:

  1. Substations: In medium voltage substations, earthing switches are used during maintenance or fault conditions to ensure that particular sections are safely grounded.
  2. Switchgear Assemblies: Within switchgear setups, earthing switches are integrated to ground specific sections, making it safe for operators to conduct maintenance or repair tasks.
  3. Capacitor Banks: When capacitor banks need servicing, earthing switches ensure that these high energy storage units are safely grounded, protecting service personnel from potential electrical hazards.
  4. Motor Control Centers (MCC): In MCCs, earthing switches play a role in grounding motor circuits during maintenance, ensuring safety from unexpected startups or residual energy.
  5. Overhead Line Sections: For medium voltage overhead lines, earthing switches are used during maintenance operations to ground line sections, safeguarding against accidental back-feed or induced voltages.
  6. Transformer Circuits: Before maintenance on transformer circuits, earthing switches provide an essential safety barrier, ensuring the transformer and its associated circuits are safely grounded.
  7. Wind Farms: In wind turbine applications, earthing switches are often used to safely isolate and ground the internal electrical systems during maintenance or fault conditions.
  8. Rail Systems: In electrified rail networks, earthing switches play a pivotal role in grounding sections of the catenary system during maintenance or fault scenarios, ensuring the safety of workers and equipment.

 

Dimensions of MJN15-24:

Medium voltage earthing switches, though often overlooked, are fundamental in ensuring safety and system integrity in a myriad of electrical applications. Their role in grounding, paired with their integration into interlocking systems, makes them indispensable components in modern electrical infrastructure. As we move towards a future with an ever-growing emphasis on electrical safety, the significance of earthing switches in medium voltage applications remains paramount.

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