Type of DC Network: Network with the middle point of the supply source connected to ground

 

DC Network with the middle point of the supply  source connected to ground | Source: ABB

This type of network is obtained by connecting the middle point of the battery to the ground. This type of connection reduces the value of static overvoltages, which could otherwise be present at a full voltage in an insulated plant. 

Grounding Solution | Source: ABB

The main disadvantage of this connection, if compared with other types, is that a fault between a terminal and ground gives rise to a fault current at a voltage V/2.


Related Article: 


Fault types in a network with the middle point connected to ground

Fault A 

The fault between the two terminals is a short-circuit current fed by the full voltage V. The breaking capacity of the circuit breaker shall be sized according to the short-circuit current relevant to such a fault.

Sample Fault: Fault at A


Fault B

The fault between the terminal and ground sets up a short circuit current lower than the fault between the two terminals as it is supplied by a voltage equal to V/2 depending on the soil resistance.

Sample Fault: Fault at B

Fault C

In this case, the fault is analogous to the previous case but it involves the negative terminal.


Sample Fault: Fault at C


With this type of network, the fault which affects the version of the circuit breaker and the connection of the poles is fault A (between the two terminals). However, the fault between a terminal and ground should also be taken into consideration because a current could flow at a voltage equal to V/2. 

In a network with the middle point of the supply connected to the ground, the circuit breaker must be connected on both terminals.


Source: 

  • ABB Circuit Breakers for Direct Current Applications | pp. 18-19
  • Publisher: ABB
  • Download Here


No comments:

Select Topics

electric protection Electrical Design power system protection Electrical Safety Fault Analysis Electrical Machines protective relaying circuit breaker electrical protection Electrical Equipment Technical Topics Electrical Installation Power System BS7671 short circuit analysis DC Circuit Earthing System Transformer power system analysis what Direct Current System Energy Efficiency Generator IEC standard Manual Resources Transmission Lines Unbalanced Fault Analysis electrical motor electrical testing grid automation power system automation smart grid tutorial video ebook how motor control substation automation symmetrical components AC Machines Advance Circuit Theory IEC 60364 Renewable Energy Voltage Drop Calculation current transformer electrical grounding schneider electric Circuit Analysis fuse generator protection power system stability quiz switchboard transformer protection ABB Manuals AC Circuit Busbar DC Machines GE Whitepapers General Electric Line to Line Fault National Electrical Code arc flash earth fault loop impedance electric vehicle electrical wiring power plant power system operation selective coordination switchgear video tutorial 3D printing ABB AREVA AUS/NZ 3000 Assignment help Busway Current Nomenclatures Electricity Spot Market G3 technology IEEE C37.2 IEEE/ANSI Device Numbers MiCom NFPA 70E Philippine Electrical Code Terms of use Theoretical UFES VFD ampacity battery building wiring capacitor circuit breaker curve cooling system cooper bussman disruptive technologies electrical earthing electrical harmonics energy industry energy savings engineering education iec 61850 inspection checklist learning process bus protective bonding single line to ground fault transmission line protection variable frequency drive voltage compensation voltage transformer voltage unbalance