AC (Air Conditioner ) consumes lot of electricity, it consumes most of the power when compressor of AC starts on loading.
Once you switch ON the AC and fixed the set point temperature in AC, if the atmosphere temperature is more than than set point temperature, compressor of AC will start running and cooling will start. It cools the atmosphere of room upto below set point temperature, once set point temperature will achieve, Compressor will stop running. Room temperature will again increase slowly and once temperature is slightly more than set point, compressor will start again. In this way compressor of AC will Cut-in and Cut-out as per set point.
Compressor will run for more time if room is big, capacity of AC is less, ambient temperature is high or you have kept the temperature set point to very low temp.
If you have installed 1 Ton AC, when compressor is on load, it consumes 3.51 KW of electricity. Meaning is that, if the compressor is loaded for 100% of time of AC running, it will consume 3.51 unit of electricity in 1 hour. If the electricity unit rate is 5 Rs , the cost of running of AC for one hour will be 3.51x 5= Rs 17.55. If you keep the temp set point to higher value so that only half of time AC compressor is getting loaded, total power consumption bill will also get halved i.e Rs 8.80 per hour.
If you select higher ton capacity i.e 1.5T AC, it will consume 1.5x 3.51 = 5.3 KW of electricity, so if compressor is loaded for 100% of AC running time, per hour unit of electricity consumption will be 5.3.
In this way you can find the power consumption of AC by taking 2 input- 1st is Ton of AC and 2nd is % of time for which AC compressor is getting loaded.
Higher capacity AC (higher ton) does not cause more electricity bill, because it cools the room very fast upto set point and Compressor Cut-off time is more in compare to low capacity AC, so overall power consumption will be almost same. But advantage of higher ton AC is that, it cools the room at very fast rate in comparison to low capacity AC.