Why AC rated in Tons, Not in kW or kVA? A Guide about Airconditioner and Refrigeration
If you pick this article, You will be able understand;
→ 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
→ 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?
→ 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
capacity
instead 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 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?
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 = 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
And
in Three Phase 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
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.
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, transformers
etc.
A general AC (Airconditioner )Name plate rating Data
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