I see ..
I thought that there is a in-built switch in single power supply to change from/to 110 and 230. When I checked the back of computer, I could see red button with "115". Does this have any connection for input power supply?
My other concern is the weight of above supply (over 4kg). Is there any other better choice?
Yes, if your power supply has a switch, you can switch it and use a different power cord, but not all power supplies have them.
If your system takes a "standard" power supply, you might be able to swap it with a different one, but you may not save much weight. Some systems also have a proprietary-shaped power supply to fit the design of the system.