The cooling produced by melting of 1 ton of ice in a day is
taken as unit of refrigeration (in tons). Now unit of
refrigeration used in S.I. System is KW.
1 ton of refrigeration
= mass of ice x latent heat of ice / 24 hrs

= 900 kg x 335 KJ/Kg ( one short ton = 900 kgs )
------------------
24 x 3600 secs
= 3.4895 KJ/Sec
say 3.5 KJ / Sec = 3.5 KW

In simple 1 tonne refregeration effect of AC is equal to
same amount of cooling which have been achieved by 1 Tonne
of ice block in 1 hour. i.e 3000K.CAL /HR

One Ton of Refrigeration is cooling capacity of a machine
that can freeze one short ton of water at 0 degree celcius
to ice at 0 degree celcius in 24 hrs.

1 tonne AC : it is the capacity of the unit, which can
remove the heat generated in the particular room ,such that
the amount of heat is equivalent to melt the 1 block of ice
(which is weighing 1 tonne).

As the one point of eac phase winding is connected to each other
in satr connction. Even if that at distribution side collesion of
two diff phases result in to blast. Why?

Dear All,
In a 400V power system, ratio of three current transformers
installed incoming switchgear is 4000/1. Maximum three
phases short circuit current of this system is 48kA. One CT
is installed on neutral of upstream transformer (6/0.42kV,
solidly earthed) for 51G protection. Would you please inform
me about the correct CT ratio of this current transformer
(on neutral)??
Thanks a million