|
|
| (8 intermediate revisions by 3 users not shown) |
| Line 1: |
Line 1: |
| {{Menu_General_rules_of_electrical_installation_design}}
| | #REDIRECT [[Estimation of actual maximum kVA demand#Diversity factor - Coincidence factor (ks)]] |
| <br>
| |
| The term diversity factor, as defined in IEC standards, is identical to the factor of simultaneity (ks) used in this guide.In some English-speaking countries however (at the time of writing) diversity factor is the inverse of ks i.e. it is always ≥ 1. <br>
| |
| | |
| ----
| |
| | |
| <br>
| |
| | |
| [[Image:Fig-A14.jpg]] | |
| | |
| '''''Fig A14:'''''<i> An example in estimating the maximum predicted loading of an installation (the factor values used are for demonstration purposes only)</i> <br>
| |
| | |
| ----
| |
| | |
| ==== <br>Choice of transformer rating<br> ====
| |
| | |
| When an installation is to be supplied directly from a MV/LV transformer and the maximum apparent-power loading of the installation has been determined, a suitable rating for the transformer can be decided, taking into account the following considerations '''(see Fig. A15):'''
| |
| | |
| *The possibility of improving the power factor of the installation (see chapter L)
| |
| *Anticipated extensions to the installation
| |
| *Installation constraints (e.g. temperature)
| |
| *Standard transformer ratings
| |
| | |
| ----
| |
| | |
| <br>
| |
| | |
| {| cellspacing="1" cellpadding="1" width="396" align="left" border="1"
| |
| |-
| |
| | bgcolor="#0099cc" rowspan="2" |
| |
| '''Apparent power kVA'''
| |
| | |
| | bgcolor="#0099cc" colspan="2" | '''In (A)'''
| |
| |-
| |
| | bgcolor="#0099cc" | '''237 V'''
| |
| | bgcolor="#0099cc" | '''410 V'''
| |
| |-
| |
| | 100
| |
| | 244
| |
| | 141
| |
| |-
| |
| | 160
| |
| | 390
| |
| | 225
| |
| |-
| |
| | 250
| |
| | 609
| |
| | 352
| |
| |-
| |
| | 315
| |
| | 767
| |
| | 444
| |
| |-
| |
| | 400
| |
| | 974
| |
| | 563
| |
| |-
| |
| | 500
| |
| | 1218
| |
| | 704
| |
| |-
| |
| | 630
| |
| | 1535
| |
| | 887
| |
| |-
| |
| | 800
| |
| | 1939
| |
| | 1127
| |
| |-
| |
| | 1000
| |
| | 2436
| |
| | 1408
| |
| |-
| |
| | 1250
| |
| | 3045
| |
| | 1760
| |
| |-
| |
| | 1600
| |
| | 3898
| |
| | 2253
| |
| |-
| |
| | 2000
| |
| | 4872
| |
| | 2816
| |
| |-
| |
| | 2500
| |
| | 6090
| |
| | 3520
| |
| |-
| |
| | 3150
| |
| | 7673
| |
| | 4436
| |
| |}
| |
| | |
| <br>
| |
| | |
| <br>
| |
| | |
| <br>
| |
| | |
| <br>
| |
| | |
| <br>
| |
| | |
| <br>
| |
| | |
| <br>
| |
| | |
| <br>
| |
| | |
| <br>
| |
| | |
| <br>
| |
| | |
| <br>
| |
| | |
| <br>
| |
| | |
| <br>
| |
| | |
| <br>
| |
| | |
| <br>
| |
| | |
| <br>
| |
| | |
| <br><br>
| |
| | |
| <br>
| |
| | |
| <br>
| |
| | |
| <br>
| |
| | |
| '''''Fig. A15'''''<i>: Standard apparent powers for MV/LV transformers and related nominal output currents</i>
| |
| | |
| ----
| |
| | |
| The nominal full-load current In on the LV side of a 3-phase transformer is given by:
| |
| | |
| <math>\mbox{In}=\frac{\mbox{Pa}\times10^3}{\mbox{U}\sqrt3}</math>
| |
| | |
| *Pa = kVA rating of the transformer
| |
| *U = phase-to-phase voltage at no-load in volts (237 V or 410 V)
| |
| *In is in amperes.
| |
| | |
| For a single-phase transformer:
| |
| | |
| <math>\mbox{In}=\frac{\mbox{Pa}\times10^3}{\mbox{V}}</math> <br>where
| |
| | |
| *V = voltage between LV terminals at no-load (in volts)
| |
| | |
| Simplified equation for 400 V (3-phase load)
| |
| | |
| *In = kVA x 1.4
| |
| *The IEC standard for power transformers is IEC 60076.
| |
| | |
| <br>
| |
