(020) SF6 Gas Density Pressure Gauge

SF6 gas density controller specifically designed for the control of voltage switchgear systems. This instrument is ideally suited for indoor and outdoor environments and provides highest levels of operational safety and reliability. The integral bimetal compensation guarantees a maximum of operational safety in SF6 gas insulated switchgear systems. 

Introduction

Sulphur Hexafluoride (SF6 Gas) is an inorganic, non toxic, non flammable gas that is five times the density of air and has a high dielectric strength. Because of this high dielectric property, SF6 gas is ideal for use in the power distribution industry where the “make and break” in high voltages circuit breakers results in electric arcing which would burn out the contacts if not isolated.  Common applications for SF6 Gas as an isolation gas can be found in High Voltage Circuit Breakers (above 35000V), Gas Insulated High Voltage Cables and Transformers. Unfortunately SF6 gas does loose its isolation properties if its pressure is allowed to drop, it is also the worst “greenhouse effect” gas so for both of these reasons it always has to be carefully monitored and controlled.  

Construction

SF6 Gas expands rapidly with elevated temperature which effectively increases the pressure under which it is stored. This increase in pressure can give inaccurate volume readings if not compensated for. Our SF6 Gas Controller features a bi-metallic temperature compensating device fitted between the gauge movement and the bourdon tube to eliminate any error in reading due to temperature fluctuations. This compensation allow the volume to be carefully monitored at a base reference temperature of 20C 

Design

Each SF6 Density Controller is manufactured for the given application. Because of this the following information is always required:

Pf – (Filling Pressure). This is the pressure of the SF6 Gas in the High Voltage Circuit Breaker at 20C

Pcal – (Calibration Pressure). This is the reference pressure for the temperature compensation based on 20C.

Ps – (Switch Points). This is the switch point for the contact at 20C. It is possible to have up to 4 magnetic, sliding or inductive contacts which can be set to make or brake on rising or falling pressure.