D56 - Gas Density and Pressure Monitoring
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COMDE DERENDA Densistat 56 for SF6 and other Gases Type: D56 for outdoor or indoor use The Densistat Model 56 is designed specially to monitor the density of the SF6 gas used to blanket high-voltage circuit breakers. It incorporates a gauge for relative pressure, referenced to 20 °C. ■ Pressure range 0...10 bar rel. 0...145 psi rel. ■ Pressure gauge 55 mm 0 ■ High long term stability ■ Precise switching accuracy IEC 60529 : IP 67 / IP X5 ■ Up to four micro switches The Densistat 56 uses a chamber filled with an identical gas as a reference. When the reference chamber and the switching enclosure are at the same temperature, a change in density in the latter will induce a pressure differential. The switching enclosure and the reference chamber are separated one from another by a metal bellow. A differential in pressure will cause a deformation of the bellow. This deflection motion is transferred via a switching rod with a switching plate to actuate the microswitch required for signaling purposes. The switching thresholds can be adjusted by way of lockable screws at the switching cam. Up to four micro switches with double-throw contacts can be installed in the Model 56. The contact outputs for the micro switches terminate in an appropriate multi pole socket inside the junction box. The corresponding connector cable passes to the outside world through a suitable cable gland. The junction box cover, the cable gland, the connector cable and the plug-type connector form a unit that can easily be mounted and removed with just a screwdriver. The analog pressure indicator with color-coded scale (55 mm diam.) shows the relative pressure of the SF6 gas, referenced to 20°C in the switching enclosure. If the density of the gas drops as a result of a leak, the change will be indicated by the pointer as it moves along the color- coded scale. The colors and the transition points along the scale can be specified by the customer. The micro switch response points are then calibrated to the specified values. The arrangement of the measurement mechanism and the use of vibration-resistant micro switches eliminate any shock-induced chattering at the switching contacts. The unit is equipped with a GORE-TEX® membrane vent to prevent condensation. Comde-Derenda GmbH Kieler Strasse 9, 14532 Stahnsdorf / Germany info@comde-derenda.de www.comde-derenda.de

COMDE DERENDA Technical Data Densistat 56 Range: Hysteresis: Switching accuracy: Threshold: Leakage of reference chamber: Operating temperature: Storage temperature: Indicator diameter: Tolerance of indication: Vibration (min. difference 0.05 bar from changeover point): Protection: Connector: Standard 3 micro switches: Electrical rating: Switch contacts load, charge resistive (inductive): Electric strength: Surge: Cable gland: Material: Reference system: Window, resistant to UV, Ozone: Typeplate, resistant to UV, Ozone, Climate, chemicals and solvents: Weight: Comde-Derenda GmbH reserves...