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# Why AC rated in Tons, Not in kW or kVA? A Guide about Airconditioner and Refrigeration

→ Why AC rated in Tons, Not in kW?
→ Definition of Ton

How many kW and HP are there in 1 Ton?
How to convert Ton to Kw and vice versa?
How much Current in Ampere will a 2 Tons AC draw in Single Phase & Three Phase
System?
→ How many 2 Ton A.C (Air conditioner) can I run on a 25 kVA Generator?
What is the suitable rating of MCB for 2 Ton and 1 Ton AC (Air conditioner) and why?
and much more…
Click image to enlarge

Why AC rated in Tons, Not in kW?
AC (Air-conditions and Refrigeration are always rated in Tons.
Air conditioners are always rated in Tons capacityinstead of kW because Air conditioners are designed on the basis of quantity of heat removal from room, hall or specific area. Quantity of heat is termed in Tons means if an air conditioner is able to remove 1000 kilocalories of heat or 4120 kilojoules or 12000 BTU of heat in an hour that AC rated as 1 Ton of AC because 1000 Kilocalories or 4120 kilojoules or 12000 BTU equal to one Ton of heat. Also, this is the same case for freezer and refrigerator i.e. refrigeration system.
Good to know:
BTU = British thermal unit. A measurement of heat, specifically, the amount of heat needed to raise the temperature of a pound of water by 1°F.
Definition of Ton
A Ton of refrigeration (RT) is approximately equivalent to 12,000 BTU/h or 3,516.8528 W or 4.7142Hp.
A Ton of refrigeration (RT) is a unit of power used to describe the heat-extraction capacity of air conditioning and refrigeration equipments. It is defined as the heat of fusion absorbed by melting 1 short ton of pure ice at 0 °C (32 °F) in 24 hours.
How many kW and HP are there in 1 Ton?
1 Ton = 3.5168525 kW = 4.714Hp
Explanation
1 Ton = 12,000 BTU/h
1 Watt = 3.412141633 BTU/h
1 Ton = 12,000 / 3.412141633 = 3,516.8528 Watts = 3.5168528 kW.
1 Ton = 3,516.8528 Watts = 3.516 kW.
Also
1 Ton = 3,516.8528W / 746 = 4.7142798928 Hp →→→ (1 Hp = 746 Watts)
1 Ton = 4.714 Hp
How to convert Ton to Kw and vice versa?
One RT(Refrigeration Ton) = 3.5168528 kW…
1 RT = 3.5168528 kW
1 kW = 0.284345 RT(Refrigeration Ton)
1 kW = 0.28434517 RT
So,
The power P in kW = Power P in RT (Refrigeration Ton) times 3.5168528….
P(kW) = P(RT) × 3.5168528
Example
Convert 3 Ton AC into kW i.e. Convert 3 RT to kW.
Solution:
P(kW) = 3 RT × 3.5168528
P(kW) = 10.55 kW
3 Ton AC = 10.55 kW
How much Current in Ampere will a 2 Tons AC draw in Single Phase & Three Phase System?
Suppose, There are 230V and Power factor = Cosθ = 0.95 in Single Phase AC system
1 Ton = 3,516.8528 Watts = 3.516 kW.
2 Ton = 2 x 3.516 kW = 7.032kW = 7032W
Power in a Single Phase AC System
P = VxI Cosθ and current…
I = P / (V x Cosθ)….. Where Cosθ = Power factor
I = 7032W / (230V x .95)
I = 32.18 A
Therefore, a 2 Ton AC (Air-condition in Single Phase AC system will take 31.18 Ampere Current
Andin Three Phase System
Suppose, There are 440V and Power factor = Cosθ = 0.85 in Three Phase AC system
Power in a Three Phase AC System
P =√3 x VLxIL Cosθ and current….
I = P /( √3xVxCosθ)
I = 7032W / (1.732 x 440V x .85) Where Cosθ = Power factor and √3 = 1.732
I = 10.855 A
Therefore, a 2 Ton AC (Air-condition in Three Phase AC system will take 10.855 Ampere Current
Good to Know:This is just calculation based on Electrical formulas. In real, Air conditioner current depends a lot on operating conditions such as ambient temperature, refrigerant pressure, Energy Efficiency Ratio (EER) etc. for instance, if EER is 6, then input power for 2 Tons Air conditioner is 24000BTU/ 6 = 4000 watts..
If this is a 230 volt system, then air conditioner load current would be = 4000/(230x.95) = 18.5 A
For More detail…Check the Air conditioner Name plate rating.
Another similar rating is Coefficient of power (COP) which is the output power in watts divided by input power, so with a COP = 1.8, for instance, input power for 2 Tons Air conditioner  is 7032W / 1.8 = 3906 watts. Now you can find current by using the above method which is equal to 18A approx.
How many 2 Ton A.C (Air conditioner) can I run on a 25 kVA Generator?
2 Ton = 2 x 3.516 kW = 7.032kW = 7032W
The Efficiency of Utility Power Generator is 90% approximately.
Efficiency of Generator = 25kVA x (90/100) = 22.5kVA
Now the Number of 2 Ton AC (Air conditioners) which you can run on a 25 kVA Generator smoothly..
22.5kVA / 7032W
= 3
So you can run Three Air conditioners of 2 Tons each on a 25kVA Generator.
What is the suitable rating of MCB for 2 Ton and 1 Ton AC (Air conditioner) and why?
As we have calculated the load current for 2 Ton AC Air conditioner…
Calculated Current for 2 Ton A.C = I = 32.18 A
Now 40A Class “C” MCB (miniature circuit breaker) would be suitable for 2 Ton AC (air-condition) because in starting time it takes more current of the full load current
And 20 A Class “C” MCB would be better for 1 Ton AC (air-condition)
Good to Know:
Class “’C’ Type MCBs
Class “C” Type MCBs are suitable for installations with high inrush of current at the starting switching time. in other words, equipment and devices having inductive loads such as air-conditioners, induction motors, fluorescent lamps, transformersetc.
A general AC (Airconditioner )Name plate rating Data
Click image to enlarge

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1. why we take power factor 0.95 in single phase while in 3 phase we take it 0.85..???

• @ Junaid Khan…<br />We took it as a reference…in real calculation…you will have to take actual Power factor value…

• thanks for your precious time…

• Most welcome…And Thanks for Your appreciation …

• @electrical technology<br />i am mechanical engineer just graduated and have a very common question which i couldnt ask during my course duration.<br />1 ton= 3.52 kW approx but on our A.c it is written cooling capacity 12000 Btu/hr ( thats 1 ton) but also written Power Consumption 1348 W .. if its 1 ton it have to consume 3520 W for rated cooling? what is point i am not getting from the relation

• The calculations are grossly wrong, as One ton of AC means the removal of that much of heat or energy or whatever, it does not mean the consumption of that much of power. In practical cases an AC system to remove one ton of consumes around 1.2KW, moreover the compressor in practical conditions run only for 30% time. I never expected this kind of theoretical mistake in an engineering page.

Power consumed = Heat Rejected – Refrigeration effect (Law of conservartion or Carnot Refrigeration cycle)

Now,in above calculation,Heat rejection is assumed as zero (PPM1) so Power consumed = Refrigeration effect .

In actual case EER or COP & Rerigeration effect determine actual Power consumption (as above calculations).

SO Electrical Technology calculations are perfectly RIGHT one from IDEAL (PPM1) & other from REAL point of view.

Hope this work !

• due to the variation in phase current

2. i have seen some company r introducing their AC which consume power less than a Hair Dryer..<br />How??

3. Great piece of Information!

4. You have hit on the bulls eye. you article is just amazing and reading it again and again is still not enough. There is some kind of charisma in your article that draws me towards reading it again and again and again

5. i am mechanical engineer just graduated and have a very common question which i couldnt ask during my course duration.<br />1 ton= 3.52 kW approx but on our A.c it is written cooling capacity 12000 Btu/hr ( thats 1 ton) but also written Power Consumption 1348 W .. if its 1 ton it have to consume 3520 W for rated cooling? what is point i am not getting from the relation

6. i have read my orient a.c specification 1 ton with 1950W.but here in calculation your result is 3150W….what wrong with these.can anyone explain

7. I am a consumer of Calcutta Electric Corporation. In my electric Bill Load (KVA) is written as 0.9. Whether this load is sufficient for running one 1.00 Ton Air Conditioner ?<br />MAdhab Char

8. Note the claculation to as below : <br />If 1 TR = 1000 K Cal / Hr ….then it is =1000*4.18/3600 = 1.2 KW.<br />Actually,<br />1 TR = 3024 K Cal / Hr……that comes to =3024*4.18/3600 = 3.5 KW.<br /><br />This is the thermal power equivalent of 1TR by definition.

9. 1 ton=3.5kw…in this 3.5kw is electrical power or its like cooling capacity unit…please any one explain me

10. 1 ton=3.5kw…in this 3.5kw is electrical power or its like cooling capacity unit…please any one explain me

11. The clarification above for converting TR to electrical power is not correct. 1 TR is equal to 3516 W is not electrical power. It is mechanical power. we need find out how much electrical power required to generate that much mechanical power. 1.7kW split type air conditioner can generate 1 TR or 3.516 Mechanical KW.

12. dear sir explain me ac and dc difference and also dc motor tarq and ac motor tarq

13. In above discussion it is seen that 1.2kwatt electric power can generate 3.516kwatt cooling or mechanical power. But we know that energy (power*time) can not be increased (nor destroyed); can only be converted into another form. Here, is not the conservation of energy rule failed? Will anyone explain more details?

14. carlo villarta

Haha nice thankyou xo much .. electrical technology

15. See name plate and clarify the above issue

16. 2 Tonn of refrigeration is equal to 3.51×2 kw in the sense of cooling capacity. But Actually in the sense of electrical engineering when we are considering, the power input for a 2.0 tonn AC will be in the range of 2.6-2.8 kw, Normally taken as 2.8 KW.

now 25 Kva genset x 0.9 efficiency = 22.5 KVA

Power consumed by 2.0 Ton ac is 2.8 KW

Now 22.5/2.8 = 8.03 ~ 8 NOs.

ie, 8 Numbers of 2.0 Ton AC can loaded by an 25 KVA generator.

i need how many kw of 174 ton air conditioner

18. Sir,

I want to know the details about chiller & its operation.

19. junaid mumkekar

hiiii…..

20. vipin mathews

we have learnt that 1 Ton = 1400 W = 12000 Btu/h…….then why here posted that 1 TON= 3.516 KW….OR am i wrong …..anywy pls try to justify & make me clear the doubt ….am an electrical engineer …..Is there any problm in just looking the name plate details ,means the max current and confirming the MCB according to that current which were shown on name pate ….rather going for ton ,kw calculations…….please reply to this also