dry type transformer ventilation details

[28021984]

hi

2nos. of 5MVA and 2nos. of 2.5MVA DRY TYPE TRANSFORMERS are installed in the 26 x 6 m room.

i would like to natural ventilation is adequate or any additional ventilation to be required for this area.

let me know what IEC which refers the ventilation arrangement of transformer and swithcgear room?

 

[dpc]

It's pretty straightforward - the transformers are rated for a certain maximum AVERAGE ambient temperature, as is other equipment that might be located in the room.

The transformer will have fixed no-load (core) losses and load (winding) losses that vary as the square of the current. ALL of these losses end up as heat rejected into the room. You need adequate ventilation and probably cooling to keep the ambient temperature of the room below the maximum allowed for whatever equipment in the room has the lowest ambient rating.

I don't know about IEC, but in general, 15 MVA of dry type transformer is going to generate a boat-load of heat if it is loaded. Unless this is in Greenland or Antarctica, I suspect you will at least need some forced ventilation, if not some type of cooling.

 

[7anoter4]

The natural ventilation efficiency does not depend upon the area occupied by equipment.
The ventilation ratios can be calculated with the following formula
ΔϑL^3*H=13.2*Pv^2/A1^2*(R1+m^2*R2)
ΔϑL=T2-T1
Pv=sum of all losses [kw]
The resistance of the air path is generally:
(R1+m^2*R2)
Here: R1 resistance and acceleration figures
in the incoming air duct, R2 resistance and
acceleration figures in the exhaust air duct, m ratio of the cross section A1 of the
incoming air duct to the cross section A2 of the exhaust air duct.
For example:
acceleration 1 ; slow change of direction 0…0.6 ;
right-angle bend 1.5 ; wire screen 0.5…1;
rounded bend 1; slats 2.5…3.5;
a bend of 135 ° 0.6; cross section widening 0.25…0.9;
Usually R1~3 and R2~6
H = “chimney” height[m] the height of exhaust air area centerline above Ground.
See:
ABB Switchgear Manual ed.11 ch.4 Dimensioning switchgear installations
4.4.2 Ventilation of switchgear and transformer rooms

From Siemens GEAFOL Cast-Resin Transformers: Planning Guidelines
Ventilation of the Transformer Room
The following applies to that portion of
the heat losses which is dissipated by
Qv1 = 0.1 * A1.2 *sqrt( H x ΔϑL^3) [kw]
See:

http://www.google.co.il/url?sa=t&rc...rce=web&cd=3&sqi=2&ved=0CFYQFjAC&url=https://

http://www.cee.siemens.com/web/slov...muDaCg&usg=AFQjCNG3HIS-s6sqtVb-x7QHJ53iyhEKcA