Thanks for this question Swetha

I read about the Personal, Social and Transpersonal Planets some months ago but then I let it slip out of my mind...it is only when I saw this topic that I realised that I had read about them somewhere...
Alright so here it is...

It is always useful and important to know how much time does it takes for the planets to complete an orbit around the sun which is the same amount of time it takes to complete a revolution on ones birth chart. It is also to be noted that the planets move on the chart in a counter clockwise motion, except the nodes.

The personal planets include the sun, the moon, Mercury, Venus, and Mars.
The social planets include Jupiter and Saturn.
The transpersonal planets include Uranus, Neptune, and Pluto.

These Personal, Social and Transpersonal Planets are just categories based on the distance of plantes from the sun and their effects can be generalised as per their names. I won't go into details but here is a little something about each of them:

PERSONAL PLANETS
SUN: The SUN expresses our personal identity and awareness of conscious personality. It represents the realisation of the 'self', the essence of 'being', and the vitality of life.

MOON: The MOON expresses our instincts, habitual reactions, emotional responses and subconscious conditioning.

MERCURY: MERCURY represents thinking, learning, and the communicating faculties. It imparts the capacity to rationalise, imagine, and mentally identify with the world.

VENUS: VENUS represents pleasure, the enjoyment of relationships, loving and caring. It helps us to decide what is relevant to well being and happiness, what is irrelevant, and what is bad.

MARS: MARS represents the energy used in asserting ourselves, in fighting for what we wish to achieve and in taking decisive action. If any one word sums up Mars, it is 'action'.

SOCIAL PLANETS

JUPITER - This is energy used in expanding, growing, enlarging and exploring a wider scope in life, to challenge existing norms in society.

SATURN is the compressive energy of discipline, limitation and structure. It empowers us to apply self-regulating habits, and offers the desire and ability to achieve maturity and status by living our lives according to set norms and paradigms.

TRANSPERSONAL PLANETS

Transpersonal means the that the planets significance lies more in the collective experience than in personal experience. For example, Uranus represents technological advancement, and through such advancement we individuals, as part of our society, have gained and in many ways lost as human beings. Neptune represents spiritual advancement and again this has brought mixed blessing. Pluto represents a destructive but reconstructive force in generations and individuals.

I would request Ben or anybody practicing the western sys to tell us more about this as this is primarily used in western system.

thanks Sahil:)