Why AC rated in Tons? A Guide about Airconditioner and Refrigeration

By Bharat Ribadiya -

[accordion] [item title="In this article"]
1-Why AC rated in Tons?
2-How many kW and HP are there in 1 Ton?
3-How many Ampere will a 2 Tons AC draw in Single Phase & Three Phase System?
4-How many 2 Ton A.C (Air conditioner) can I run on a 25 kVA Generator
[/item] [/accordion]

1-Why AC rated in Tons?

Air conditioners(AC) are rated in Tons instead of using the kW unit. Just because of Air conditioners are designed on the basis of the quantity of heat removal from any specific area(office, classroom, hall). Quantity of heat is termed in Tons unit.

If an air conditioner is able to remove 2000 kilocalories of heat (8240 kilojoules or 24000 BTU )of heat in an hour that AC rated as 2 Ton of AC. Also, this is the same for the refrigeration system.

Definition of Ton: A Ton of refrigeration (RT) is a unit of power used to describe the heat extraction capacity of an air conditioner or refrigeration equipment. 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.

A Ton of refrigeration (RT) is approximately equivalent to 12,000 BTU/h or 3,516.8528 W or 4.7142Hp. BTU  is known as British thermal unit. This is used for the measurement of heat, specifically, the amount of heat needed to raise the temperature of a pound of water by 1°F.

2-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

So,
 1 Ton = 12,000/3.412141633 = 3,516.8528 Watts = 3.5168528 kW
 1 Ton = 3.516 kW

And,
1 Ton = 3,516.8528W / 746 = 4.7142798928 Hp (Where 1 Hp = 746 Watts)
1 Ton = 4.714 Hp


3-How many Ampere will a 2 Tons AC draw in Single Phase & Three Phase System?

Suppose, There are 230V and Power factor = 0.95 in Single Phase AC system.

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)
I = 7032W / (230V x 0.95)
I = 32.18 A

↳Therefore, a 2 Ton AC in Single Phase AC system will take 31.18 Ampere Current

Suppose, There are 440V and Power factor = 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)
I = 10.855 A

↳Therefore, a 2 Ton AC in Three Phase AC system will take 10.855 Ampere Current.


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.

2 Ton = 2 x 3.516 kW = 7.032kW = 7032W

Efficiency of Generator =22.5kVA / 7032W
                                           = 3

So you can run 3 Air conditioners of 2 Tons each on a 25kVA Generator.


4-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-conditioner) because in starting time it takes more current to the full load current and 20 A Class “C” MCB would be better for 1 Ton AC (air-conditioner).

If you question about this article, please comment below.

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