Solidly grounded system

 Solidly grounded system :

 This type of grounding system is most commonly used in industrial and commercial power systems, where grounding conductors are connected to earth ground with no intentional added impedance in the circuit. A main secondary circuit breaker is a vital component required in this system, although it has no bearing in other grounding systems. This component is large in size because it has to carry the full load current of the transformer. Back-up generators are frequently used in this type of grounding system in case a fault shuts down a production process. When this happens, the generators become solidly grounded. However, it’s important to note that the generators aren’t designed for the larger short circuit current associated with solidly grounded systems.

A solidly grounded system has high values of current ranging between 10kA and 20kA. This current flows through grounding wires, building steel, conduit, and water pipes, which can cause major damage to equipment and shut down production processes. When a line-to-ground fault occurs, arcing can create flashes–generally in the terminating box. In this enclosed area, water is turned to steam, causing the terminating box. To locate the fault, all you need to do is follow the smoke.

Advantages

• Good control of transient overvoltage from neutral to ground.

• Allows user to easily locate faults.

• Can supply line-neutral loads.

Disadvantages

• Poses severe arc flash hazards.

• Requires the purchase and installation of an expensive main breaker.

• Unplanned interruption of production process.

• Potential for severe equipment damage during a fault.

• High values of fault current.

• Likely escalation of single-phase fault to 3-phase fault.

• Creates problems on the primary system.