This standard specifies the dedicated terminologies, test items and test methods relevant to the SF6 gas tightness for high-voltage switchgear.
The test methods specified in this standard are used for testing the relative yearly leakage rate of switchgear/compartment.
This standard is applicable to the gas tightness test for high-voltage switchgear with SF6 gas as arc extinguishing and insulating medium.
2 Terminologies
2.1 Closed pressure system
The switchgear/compartment which is refilled only periodically by manual connection to an external gas source.
2.2 Sealed pressure system
The switchgear/compartment for which no further gas processing is required during its expected operating life.
2.3 Rated filling pressure, pr (gauge pressure)
The pressure in bars (gauge) referred to atmospheric air conditions of 20℃ and 1,013 hPa at which the gas-filled compartment is filled before being put into service or automatically refilled.
Note: it may be represented by density rated filling density Dr.
2.4 Minimum functional pressure, Pmin, (gauge pressure)
The gas pressure in bars (gauge) referred to atmospheric air conditions of 20℃ and 1,013 hPa at and above which the rated values of the switchgear are maintained.
Note: it may be represented by the minimum functional density Dmin.
2.5 Absolute leakage rate (hereinafter referred to as leakage rate), F
The amount of gas escaped by time unit, expressed in MPa·m3/s.
2.6 Permissible leakage rate, Fp
The maximum permissible leakage rate for the complete high-voltage switchgear/compartment or several as-filled compartments combined into one gas system (gas-tight assembly), by using the tightness co-ordination chart TC.
2.7 Relative yearly leakage rate (hereinafter referred to as yearly leakage rate), Fy
The absolute leakage rate related to the total amount of gas in the switchgear/compartment at rated filling pressure within certain time interval. It is expressed as a percentage of yearly leakage amount.
2.8 Time between refillings, T
