An industrial complex with a small financial budget uses two transformers to supply their internal power system. The transformers are connected to a switch board as shown in the SLD below and together they supply four identical loads (at unity load factor) which amounts to 20 MVA. Both transformer impedances are defined on the ONAN MVA base. i. ii. TF #2 33/12 kV 7/12 MVA 11% iii. 12 kV Bus iv. Zone 1 XA 33 kV Bus - Utility (Infinite Bus, 1 p.u.) L1 L2 (5 MVA) (5 MVA) BS CB TF #1 33/12 kV 13/16 MVA 21% XA L3 L4 L5 (5 MVA) (5 MVA) (5 MVA) Figure Qu. 3 Expansion of the industrial complex is expected in 2023 and this will cause a further 5 MVA load to be supplied from the pair of transformers. Due to physical space constraints, this additional demand must be supplied from a 12 kV feeder connected to Zone 2 of the 12 kV switchboard. Future As the electrical engineer for the industrial complex, use the information provided on the SLD to report to your senior management, if the existing infrastructure is adequate to accommodate the 5 MVA expansion. Your response must include: Drawings and/or mathematical calculations used to justify your position. (8 marks) Zone 2 Bus Section Circuit Breaker (Normally Closed) A description of how the system will perform, clearly identifying any major issues which may occur if an additional 5 MVA is to be connected to the existing system. (2 marks) Page 5 of 7 The CEO insists that the proposed expansion must take place and that you must find a way to make the existing infrastructure work. Suggest a temporary solution which can be implemented to ensure that the expansion takes place. Keep in mind that the CEO of the industrial complex will not approve funding for any new equipment (and therefore your temporary solution should be one related to operating policy, rather than a recommendation for procurement of new equipment). (1 mark) Assuming that L2 and L3 are the most critical loads in the industrial complex and that these loads should only be shed after all other loads are lost, comment on any undesirable effects which may arise as a result of your proposal in (iii). (2 mark)