1. Define briefly: (a) the fault level of a system or unit in a system (b) base MVA.

State: (c) the equation for percentage impedance or impedance voltage (d) the relationship between X% and X pu (e) the units of X% and X pu

(f) X pu in terms of the fault level MVA and the base MVA. 2. Draw the individual and combined impedance (X pu) diagrams to a base of 10 MVA for the units and system shown in FIGURE 1. Determine the

system fault MVA and fault currents at the 11 kV and 3.3 kV busbars. Show all working.

3. For the system shown in FIGURE 2, using a 10 MVA base, calculate the fault MVA levels through each unit and the base "voltage" MVA across

each unit for a fault at F. Draw the impedance diagrams showing the fault levels and the base "voltage" MVA across each unit for:

(a) bus section switch B open and A open (b) bus section switch B closed and A open. Other circuit breakers are closed.