Type B RCDs

  • Sibert B type RCD

'B' type RCDs in addition to normal AC, can detect high frequency AC and pure DC earth leakage currents. Reducing the risk of fire and/or electrocution through automatic disconnection of the electrical supply relies on the selection of the correct type of RCD. These 4P (4 module width) devices range from 16A to 125A in standard sensitivity ranges of 30mA, 100mA and 300mA.

Each unit has a contact position indicator, in addition to a reset position, which shows whether the device has been switched off manually or tripped due to a fault. The devices accept both pin and fork busbar, the pin terminal having a maximum cross-section of 50mm. These RCDs also have a facility to accept a circuit identification label behind a clear plastic window on the front of the unit.

Applications requiring 'B' types include:

  •     PV installations
  •     Frequency converters
  •     UPS installations
  •     High-frequency power converters
  •     Building site power supply cabinets

Specifically related to grid-tied Solar PV installations, and especially with the growth in use of TL (Transformerless) inverters, the correct selection and use of a B Type RCD is imperative to ensure proper and adequate protection of the AC circuit and PV system.

These Doepke B Type RCDs are available in 3 different types (NK, B+ and SK), depending on the characteristics of the installation environment and equipment being used. A useful selection guide can be downloaded from the links on the right to aid the selection process.

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