f = PN/120 where f is frequency of power supply, P is number of poles in the machine and N = speed in rpm. So, Synchronous speed N = 120f/P. Thus for 50 Hz supply, 2 pole machine; synchronous speed = 3000rpm. ETRICAL
Within our solar system quite a bit of exploration has been done by spacecraft including orbiters and landers. Planets outside our solar system will be difficult or impossible to explore with spacecraft in our lifetimes, so astronomers and astrobiologists use other techniques to search for signs of life on these planets. In particular, astronomers are interested in planets within the habitable zone of stars.
The inner planets (in order of distance from the sun, closest to furthest) are Mercury, Venus, Earth and Mars. After an asteroid belt comes the outer planets, Jupiter, Saturn, Uranus and Neptune.The interesting thing is, in some other planetary systems discovered, the gas giants are actually quite close to the sun.This makes predicting how our Solar System formed an interesting exercise for astronomers.rtistâs impression of the solar system showing the inner planets (Mercury to Mars), the outer planets (Jupiter to Neptune) and beyond. Credit: NASA. In our Solar System, astronomers often divide the planets into two groups â the inner planets and the outer planets.