Medium voltage grounding resistor

The RAM is a set of resistors to ground medium voltage electrical systems with great reliability and safety, following the requirements and recommendations of NR-10 and acting between 2.4 kV and 34.5 kV. If there is a need to supervise the neutral-ground circuit online, we have the UMT-02 RAM model, which has this functionality.


The use of medium voltage resistors

The installation of grounding resistors in neutral transformers and generators is one of the most established ways of limiting earth fault currents, especially in medium voltage applications. This solution has advantages such as the conception of a personal protection and safety philosophy allied to the limitation of the efforts due to the short circuit current.

Technical Features

  • Electrical system rated voltages: 2.4kV to 34.5 kV (*);
  • Phase-neutral voltage: VØ-Ø/ 3 kV;
  • Rated currents: 25, 50, 100, 200 and 400A (*);
  • Charging time: 10 seconds (*);
  • Rated frequency: 60Hz;
  • Natural ventilation system for the resistors;
  • Aerial entry or through insulated cables;
  • Rated technical characteristics of the Current Transformer (if applicable) to be defined as a function of the electrical system rated data.

 (*) Other figures on consultation

Constructive Features

  • Enclosure made of 12USG sheet steel;
  • Resistive elements in stainless steel AISI 304, mounted on ceramic supports;
  • Electrostatic painting, light grey MUNSELL N6.5 final colour (other colours on request);
  • Installation on time or sheltered;
  • Delivery with or without transformer arising, in accordance with the needs of the user;
  • Total Mass: (Kg) (**);
  • Main dimensions: (HxWxD) mm(**).

(**) Data to be confirmed according to the technical characteristics of the equipment.

Simplified Electrical Diagram

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