1. The Necessity to check the SF6 density relay
The SF6 switch is a high-voltage appliance widely used in power systems. The reliable SF6 switch has become one of the most important concerns of the power supply sector. The SF6 gas density relay is an important component used to monitor the change of sf6 gas density in the SF6 switch , and its performance directly affects the operational safety of SF6 switch.
Because the SF6 gas density relays don’t switch often , after a period of time they often appear inflexible action, poor contact and other phenomena, some will also appear density relay temperature compensation performance deterioration, when the ambient temperature mutation often leads to SF6 density relay misalignment. Therefore, the SF6 gas density relay should be checked regularly. From the actual operation, it is also necessary to carry out regular verification of SF6 density relays in field operation.
2. The basic verification principles of SF6 density relay
The gas pressure in the confined container varies with temperature, and the relative pressure value of SF6 at 20 degrees Centigrade is usually used as the standard value. During on-site verification, the SF6 pressure values measured at a certain ambient temperatures are converted to their equivalent pressure values at 20 degrees Centigrade to determine the performance of density relays.
Locking reply value check: At ambient temperature, when the SF6 density relay is zero pressure, the SF6 density relay is slowly inflated at a certain speed, when the SF6 density relay latch relay action, record the pressure value at the current ambient temperature , and converted to the equivalent pressure value at 20 degrees Centigrade , the equivalent pressure value at 20 degrees Centigrade is the SF6 density relay lock-up response value.
Alarm reply check value: continue to slowly inflate the SF6 density relay at a certain speed, when the density relay alarm relay action,record the pressure value at current ambient temperature, and converted to the equivalent pressure value at 20 degrees Centigrade, the equivalent pressure value at 20 degrees Centigrade is the alarm response value of the SF6 density relay.
Alarm value check: At ambient temperature, when the pressure in the SF6 density relay is greater than the alarm response value, slowly deflating the gas at a certain speed, when the SF6 density relay alarm relay action, record the current ambient temperature pressure value, and converted to the equivalent pressure value at 20 degrees Centigrade, the equivalent pressure value at 20 degrees Centigrade is the alarm value of the SF6 density relay.
Latch value check: continue to deflate the gas slowly for the SF6 density relay at a certain speed, when the SF6 density relay is latched, record the pressure value at the current ambient temperature, and converted to the equivalent pressure value at 20 degrees Centigrade, the equivalent pressure value at 20 degrees Centigrade is the SF6 density relay latching value.
