The ZNG-1 Pressure Relief Valve is designed to protect oil transformer tanks against mechanical damage due to abnormal pressure rise, result of a transformer overloading. The ZNG-1 valve is used in sealed transformers with tanks fully filled with oil or those provided with air cushion under the cover, The valve is mounted on the tank cover either in a specially provided pocket or is screwed on to a 1” oil filling tube. The valves can also be fitted in repaired transformers originally having no such a protection.
DESIGN AND OPERATION
A brass case 1 houses a movable rod 2 with spring 3 and cover 4 suitably sealed with a rubber, oilproof seal. Excessive pressure in the tank causes the rod to overcome the spring resistance and to move upwards to open he valve, as a result a certain amount of oil or air is removed. The reduced pressure results in closing the valve.
Note: special versions are available on request.