Read-out of density/pressure from a manometer, resp. a density switch
Wika 233.52.100 no Oil Trafag 8736
Wika 233.52.100 with oil
In many countries the Wika SF6 Manometer with a display of a 100 mm diameter is considered as the standard control unit in GIS equipment. In comparison to this unit, the „old“ 8730 with its small display was not competitive. We attempt here to make a comparison of the „100 mm Display“ to our new Density switch 87X6 with an effective diameter of 56mm.
As can be deduced from the above comparison, in terms of letter size the 87X6 can be read-out just as easy as a Ø 100mm WIKA manometer. A Wika Monometer is a 0..10 bar Manometer, i.e. the display show a pressure range of 1 MPa. The 87X6-display shows a pressure range of 150 kPa, which in fact means that the display is zoomed in the area of interest; i.e. the pressure range where the switch points are defined. Therefore, the density, resp. the pressure, can be displayed and read-out in with a higher accuracy as with a10 bar Manometer.
Switch-point accuracy:
Trafag guarantees a switch-point accuracy of +/- 10 kPa over the whole temperature range of -30°C…+50°C. If this accuracy is expressed as a % of the filling pressure of the GIS, then taking a filling pressure 0.6 MPa abs (example) results in an accuracy of 1.7%. Applying the same switch-point accuracy of +/- 10 kPa for the FSO of the WIKA manometer, i.e. 1 MPa, results in an accuracy of 1.0%.
Note this (in contrary to a manometer solution) is valid for the whole temperature range.
Accuracy of display at 20°C
Trafag guarantees an accuracy of the display of +/- 10 kPa at 20°C over the whole display range. If this accuracy is expressed as a % of the filling pressure of the GIS, then taking a filling pressure 0.6 MPa abs (example) results in an accuracy of 1.7%. Applying the same switch-point accuracy of +/- 10 kPa for the FSO of the WIKA manometer, i.e. 1 MPa, results in an accuracy of 1.0%.
Accuracy of display at Alarm set-point
Trafag guarantees an accuracy of the display of +/- 10 at the Alarm set-point over the whole temperature range of -30°C…+50°C. If this accuracy is expressed as a % of the filling pressure of the GIS, then taking a filling pressure 0.6 MPa abs (example) results in an accuracy of 1.7%. Applying the same switch-point accuracy of +/- 10 kPa for the FSO of the WIKA manometer, i.e. 1 MPa, results in an accuracy of 1.0%.
Accuracy of display at filling pressure
When the temperature deviates from the 20°C, following accuracy applies for the display: per 10°C deviation, an offset of 2kPa is added to the guaranteed accuracy of +/- 10kPa (Assumption Filling pressure = Alarm set point + 40 kPa).
Accuracy at Overpressure Alarm
When the temperature deviates from the 20°C, following accuracy applies for the display: per 10°C deviation, an offset of 5kPa is added to the guaranteed accuracy of +/- 10kPa (Assumption Filling pressure = Alarm set-point + 40 kPa).