Interested to Buy Any Domain ? << Click Here >> for more details...
Why all voltage levels are the multiples of 11KV?
- 10 Answers
- 54232 Views
- KSEB, I also Faced
- E-Mail Answers
Answer Posted / lev stroud
Firstly, not all of them are.
400kV is the top voltage transmitted in GB, and it is not a
multiple of 11. Similarly 13kV is commonly used by the
distribution networks, which also is clearly not a multiple
of 11kV.
The rail network uses 25kV for most of its connections to
the grid, also not a multiple of 11.
Countries with longer connections are known to use other
even higher HV values, again most of which are not multiples
of 11.
The voltages in common use that are multiples of 11kV are
33, 66, 132 and 275.
These are a result of many generators- particularly in the
early days of the electrical industry- working at 11kV,
which when being stepped up to transmission voltages and
down again to distribution voltages meant that the networks
at the time would use simple transformer coil ratios- 3:1,
6:1 etc.
The reason for them working at 11kV came primarily due to
the limits of such factors as insulation and eddy currents
etc in the generator modules themselves. As technology has
progressed many have stepped up to higher voltages. Often
this is 22kV as, again, the transformer ratios are simple.
In fact not only are the transformer ratios simple, but
insulator stacks can simply be doubled up on.
To change the network voltages from those that have arisen
historically would be both a vast cost and incredibly
disruptive, which is why it has not been done. It would
also require the re-tooling of almost every factory that
makes HV equipment.
However, when the higher voltage 400kV (and higher)
transmission networks were added there was no requirement
for the transformer ratios to be kept so simplistic and the
voltage was chosen based on other engineering factors instead.
Contrary to the statements above, the form factor of 1.11
for sine wave power compared to transmission losses was not
an influence.
Losses are well below 10%. 1/10 losses in a 1000MVA line
would destroy most transmission systems by melting the
conductors with 100MW of heat being dissipated along it. In
fact the entire point of HV AC transmission is to keep the
losses to a minimum.
The form factor is simply the ratio of the RMS to the
average of the absolute values. This ratio gives the
ability to calculate the DC equivalent power in a system by
comparison to the AC voltage.
The figure of approximately 1.11 would still apply at the
users end, regardless of any losses, because it is a ratio.
| Is This Answer Correct ? | 29 Yes | 4 No |
Post New Answer View All Answers
what is upper impedance and lower impedance of a distance relay
how many load we can take for lighting
What are the site acceptance tests for power cables, DG Sets, LT panels & 30kVA UPS ?
what is the defination of Cable database? What are the points are considered while preparing cable database? Is there any sample available for cable database?
HOW TO WRITE A QUENTION ANSWER? I MEAN SHORT OR LENGHTHY ? OR FROM THE BOOK AS BOOK..... SOME TIME WE GIVE A ANS FROM THE BOOK AS LIKE BOOK ND WE GET MINIMUM 60% MARKS OR MORE THEN....... THEN HOW TO FILL THE Q-PAPER?
can anyone tell me can the electromagnetic waves can be reflected back?if so how &by which material it can be reflected back?please tell me so that it can help to my wireless power trasnmission device.
what is transient stability analysis means?
i have 500 amp inductive load of motors ,,,pleas tell me how can i calculate for capacitor bank for improving my power factor to 99 .....calcullations for capacitor bank,,,,
How to determine alternating current frequency?
FEINGING DECREASES THE FLUX DENSITY IN THE AIR GAP. HOW?
How to size Air Circuit breaker (ACB)? What is the most important factors?
What is the diffrence (Technical & Construction ) between CBCT & Normal CT?
hello everybody. what does an abnormal stator winding impedance or dc resistance show? thanx
What type of DC motor would you see for a lift?
Will an earth leakage trip be activated if the component or wiring is faulty on low voltage equipment.Example An electrical Cat Scarer placed in the garden and water gets into the wiring.
