Start Learning English Hindi. This question was previously asked in. Attempt Online. Generating Voltage levels: It is cheaper to generate at a relatively lower voltage and then step it up for transmission. Hence, most power generating plants are designed to operate at 11kV. To generate at 33kV, the size of the motor might be twice as large as the size of 11kV generator.
So it is better to have a multi stage step up for transmission of voltages.. For Europe and India, 11 kV and 50 Hz is the dominant standard generator voltage and frequency. For North America, Get Started for Free Download App. More Power Systems Questions Q1. Earthing is necessary to give protection against. Obliviously, this is an interview type question for electrical engineers especially related to power engineering. Now, we are going to explain the simple logic behind the story.
First of all, It is not true that all the transmissions and distribution voltages are multiple of But kV, kV and kV etc are not multiple of 11 in case of electric power system generation, transmission and distribution in power lines from the generation station to the receiving point. Most of you may opt for form factor 1. Lets see below:. Form Factor is the ratio between the R. Mathematically, It can be expressed as. For a sinewave, the form factor is given below:.
The above calculation clearly shows that the results are different then the general values i. Also, alternator and generator with terminal voltages are available i range of 10kv — 15kV which is not to do with multiple of Now back to the point, the voltage at the receiving end are generally:.
While the receiving end voltage are 10kV due to voltage drop. More examples are given in below table. Well, this is not the end as some serious questions arise here.
If this is the reason mentioned above, then:. Valid point. But we dont know the exact value of voltage drop as it depends on the value of current where the current is not constant i. For the same rating of kVA, the higher the voltage and lower the current will reduce the line loss as well as voltage drop in the transmission line.
Most likely, it was a decision arising from a standards committee and it may be an optimum transformation ratio chosen to minimize total losses. Someone still alive may yet know the reason. Then again, it may have a legacy resembling that of the standard rail gauge. These numbers were chosen arbitrarily in the past and have actually evolved as industry standard since these voltage levels are integral multiples of 11 which further simplify the voltage transformation ratio.
In the American standard, Just like 12 inches makes 1 foot and 3 feet makes 1 yard have evolved into standard units of measure. To put this issue in a proper perspective, the choice of generation voltage will always depend on the dominant standard that is being adopted by a particular country or region. For Europe, 11 kV and 50 Hz is the dominant standard generator voltage and frequency, for North America, But large generator manufacturers can design and build a wide range of generator voltage 11 kV to 28 kV and standard frequency 50 Hz or 60 Hz , based on existing generator design, construction and insulation technology.
It is cheaper to generate at a relative lower voltage and then step it up for transmission.
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