Trihal cast resin dry type transformers (ENG) - Trinet

Trihalinstallationventilation determination of the height and area of ventilationgrills.In the general case of natural cooling (AN) theventilation of the substation or of the enclosuremust ensure by natural convection the dissipationof the heat produced by the transformer’stotal losses.In case of a no sufficiently ventilation substation,appropriate ventilation will consist of a fresh airintake opening of S section at the bottom of thelocal and an air outgoing opening S’ locatedabove on the opposite wall at height H metresabove the intake opening (figure 1).It must be noted that restricted air circulationreduces the transformer’s continuous and shortterm overload capacity.figure 1 formula for ventilation:S’S = 0.18 PHand S’ = 1.10 x SHP = sum of the transformer’s no-load and loadlosses expressed in kW at 120°C.S = area of the lower air intake opening (allow formesh factor) expressed in sq m.S’ = area of the air outlet opening (allow for meshfactor) expressed in sq m.H = height difference between the two openingsexpressed in metres.This formula is valid for an average ambient temperatureof 20 Deg.C and an altitude of 1000m. forced ventilationForced ventilation of the substation is necessaryfor ambient temperatures above 20 Deg.C orsmall or badly ventilated rooms for applicationswith frequent overloads.The fan can be controlled by a thermostat.Advised flow (m 3 /second) at 20 Deg.C: 0.1 x P.P = total losses in kW.Sforced ventilationHH mini= 160 mmS’SH mini= 160 mmFrance Transfo11