Why AC rated in Tons, Not in kW or kVA?

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Why AC rated in Tons, Not in kW or kVA?

air conditioner (AC)

Why AC rated in Tons capacity instead of kW because AC are designed on the basis of amount of heat removal from particular area or hall . 1000 Kilocalories or 4120 kilojoules or 12000 BTU equal to one Ton of heat. 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. Also, this is the same case for freezer and refrigerator i.e. refrigeration system.
where,
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°
1 Ton =12,000 BTU/h1 Watt =3. BTU/h
1 Ton =12,000 /3. =3,516.8528 Watts =3.5168528 kW.
1 Ton =3,516.8528 Watts = 3.516 kW.

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
1 Ton = 12,000 BTU/h
One 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
  • 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)
One 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 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.
  • How many currents in Ampere will a 2 Tons AC draw in Single Phase & Three Phase System?
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.
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.
  • 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).

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