Electrical Supply and Distribution Systems
| Job Title: | Electrical Supply and Distribution Systems | ||||||||||||
| Job Category: | Academic | ||||||||||||
| Word Count: | 1200 | ||||||||||||
| Job Price: | 18 | ||||||||||||
| Deadline: | 2018/02/17 12:00 | ||||||||||||
| Job Description: | 1. For a Yd1 transformer: (a) draw the connection diagram (b) show how the connections must be modified to allow parallel operation with a Yd11 transformer (c) draw a phasor diagram for the modified connection. 2. (a) Two single-phase transformers have the following impedances referred to the secondary side. Unit A rated 250 kVA (0.09 + j2.7) Ω Unit B rated 400 kVA (0.04 + j1.6) Ω Determine the load taken by each machine as a percentage of its rating when they share a common load of 500 kVA at 0.73 p.f. lag. (b) Transformer A is rated at 300 kVA with an impedance of (0.09 + j0.18) Ω Transformer B is rated at 200 kVA with an impedance of (0.09 + j0.23) Ω If these transformers are connected in parallel to supply a common load, determine the percentage overload on B when A supplies its full load at p.f. 0.45 lag. 3. From the operating chart shown in FIGURE 15 of lesson ESD – 2 – 2, determine the following performance limitations for a generator: (a) where the power limit and the MVA limit coincide; (i) the power factor (ii) the load angle (iii) the MVAr output (b) where the power limit and the stability margin coincide; (i) the p.u. excitation (ii) the MVA output. 4. A 3-phase synchronous generator rated at 570 MVA is connected to an infinite busbar. Using the data given in the table below, plot the capacity chart of the generator.
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