GENERATOR SELECTION CONTENTS - Diesel Generator

More documents

Recommendations

Info

SECTION 4595 January 1990 Page 5 In the previous table we have assumed that all the single phase loads are applied together with the transient condition ignored as discussed above. The highest load which must be sustained is given in Col. 6 on the application of load (f), 437.8 kVA. The machine selected must always have a overload capability greater than the largest kVA figure given in Col. 6. Indeed the order of load switching can be vital. To achieve the minimum size of a.c. generator based on ‘overload’ performance (Co. 6), the loads must be applied in descending order of start kVA’s (Col. 5). That is the largest start kVA load must be switched on first and the smallest last. This is the ideal situation for load switching sequence, although rarely achieved in practice. In this particular example, the ‘overload’ figures (Col. 6) are not significantly higher than the steady state total kVA. Therefore in this instance, it is unlikely that the switching sequence is that important. Hence we shall consider the worst case for ‘overload’, that is when load (f), the largest start kVA, is switched on last. This would give a total load on start kVA as follows:- 114+10.8+96.6+271 = 442.4 kVA DERATE FACTORS It is at this point in the calculation that any steady state derate factors must be applied. In this case the final power factor is below 0.8 p.f. lag, hence a derate is required. Interpolating from available date for 0.76 p.f. lag: derate factors = 0.98 Also any derates for high ambient temperature, restricted temperature rise or high altitude must be applied. In this example we shall assume that the ambient temperature is 45°C; that as the machines are insulated with ‘Class H’ materials, the associated temperature rise (125°C) is acceptable; and finally that the altitude is below 1000m. Looking at the available data; the derate factor is 0.97 (section 4401) Applying these derate factors, the selected a.c. generator must be capable of supplying a steady state kVA requirement of 330.7 = 347.9kVA 0.98 x 9.97 It is worth noting that if the derate required for transient performance demands a greater ‘kVA’ size of machine, then these steady state derate factors do not need to be applied as well. In other words either the steady state derate factors or the transient performance derate factors are applied; whichever gives the larger ‘kVA’ requirement. It is extremely unlikely that both sets of derate factors should be applied. An assessment of transient performance is given below under the heading ‘Voltage Dip Restriction’. STANDARD SIZING (a) Steady State From the summation tables we arrived at a total site load requirement of 330.7 kVA, 252.1 kW, 0.76 p.f. lag. Applying the steady state derate factor, the kVA requirement was changed to 347.9 kVA. It is this figure that is looked for in the standard output lists given in Section 2.
(b) Transient Again from the summation tables the maximum start kVA transient requirement is 271 kVA. SECTION 4595 January 1990 Page 6 The 271 kVA transient load must be checked against the voltage dip curve for the generator selected to determine the % transient voltage dip. If this level of voltage dip on starting the largest load is acceptable, then the frame size chosen also remains acceptable from a transient performance point of view. (c) Input Power The a.c. generator shaft input power is the same as the prime move shaft output power and can be estimated. The a.c. generator efficiency figures are given in the data sheet. From Section 4511: prime mover shaft = a.c. generator kW output rating power output appropriate a.c. generator efficiency
Page 1 and 2: GENERATOR SELECTION SECTION 4 Janua
Page 3 and 4: SECTION DRAWING SINGLE BEARING WITH
Page 5 and 6: SECTION 4111 January, 1990 Page 2 C
Page 7 and 8: SECTION 4111 January 1990 Page 4 Op
Page 9 and 10: SECTION 4111 January, 1990 Page 6 P
Page 11 and 12: SECTION 4111 January, 1990 Page 8 T
Page 13 and 14: Figure 2 Curve (1) machine characte
Page 15 and 16: Introduction OPERATING PRINCIPLES S
Page 17 and 18: SECTION 4131 January, 1990 Page 3 S
Page 19 and 20: A.C. GENERATOR STANDARDS SECTION 43
Page 22 and 23: 1. Basic Data A C GENERATOR SELECTI
Page 24 and 25: POWER RATING SECTION 4311 January,
Page 26 and 27: TEMPERATURE AND TRANSIENT PERFORMAN
Page 28 and 29: CONTROL SYSTEM Stamford a.c. genera
Page 30 and 31: ALTITUDE SECTION 4411 January, 1990
Page 32 and 33: CLIMATE AND ENVIRONMENT SECTION 443
Page 34 and 35: SECTION 4501 January, 1990 Page 2 I
Page 36 and 37: SECTION 4511 January, 1990 Page 2 T
Page 38 and 39: CONSTANT OR STEAD STATE LOADS - SIN
Page 40 and 41: SECTION 4521 January 1990 Page 2 Be
Page 42 and 43: SECTION 4522 January 1990 Page 4 Wh
Page 44 and 45: Since I = kW genr. and I M = kW M _
Page 46 and 47: EXAMPLES OF SELECTION FOR VARIOUS L
Page 48 and 49: LOAD (e) - 3 x 3 h.p. 3 phase motor
Page 52 and 53: POWER FACTOR CORRECTION SECTION 459
Page 54 and 55: Example Two - from an actual enquir
Page 56 and 57: Example Three To illustrate motor s
Page 58 and 59: FOREWORD ROTATING DIODE PROTECTION
Page 60 and 61: SECTION 4901 January 1990 Page 3
Page 62 and 63: 1. INTRODUCTION AND THEORY PARALLEL
Page 64 and 65: SECTION 4902 January 1990 Page 3 On
Page 66 and 67: SETTING THE DROOP CIRCUIT SECTION 4
Page 68 and 69: 4. WORKING PROCEDURE SECTION 4902 J
Page 70 and 71: 1. INTRODUCTION THREE PHASE SHORT C
Page 72 and 73: 4. SHORT CIRCUIT CURRENT DECREMENT
Page 74 and 75: CONTROL FOR GENERATORS IN PARALLEL
Page 76 and 77: SECTION 4951 January 1990 Page 3 Ma
Page 78 and 79: SECTION 4952 January 1990 Page 2 Se
Page 80 and 81: SECTION 4953 January 1990 Page 1 VO
Page 82 and 83: SECTION 4953 January 1990 Page 3 4)
Page 84: SECTION 4953 January 1990 Page 5 3)

GENERATOR SELECTION CONTENTS - Diesel Generator

Create successful ePaper yourself

Delete template?

Save as template?