Safety
To help ensure safe operation sequences of switchgear, trapped key interlocking provides predefined scenarios of operation. For example, if only one of two sources of supply are permitted to be connected at a given time, the interlock scheme may require that the first switch must be opened to release a key that will allow closing the second switch. Complex schemes are possible.
Indoor switchgear can also be type tested for internal arc containment (e.g. IEC 62271-200). This test is important for user safety as modern switchgear is capable of switching large currents.
Switchgear is often inspected using thermal imaging to assess the state of the system and predict failures before they occur. Other methods include partial discharge (PD) testing, using either fixed or portable testers, and acoustic emission testing using surface-mounted transducers (for oil equipment) or ultrasonic detectors used in outdoor switchyards. Temperature sensors fitted to cables to the switchgear can permanently monitor temperature build-up. SF6 equipment is invariably fitted with alarms and interlocks to warn of loss of pressure, and to prevent operation if the pressure falls too low.
The increasing awareness of dangers associated with high fault levels has resulted in network operators specifying closed door operation for operating earth switches and racking breakers. Many European power companies have banned operators from switch rooms while operating. Remote racking systems are available which allow an operator to rack switchgear from a remote location without the need to wear a protective arc flash hazard suit.
| 245 kV circuit breaker in air insulated substation | 420 kV gas insulated switchgear |
Read more about this topic: Switchgear
Famous quotes containing the word safety:
“An evident principle ... is the principle of justice to all peoples and nationalities, and their right to live on equal terms of liberty and safety with one another, whether they be strong or weak.”
—Woodrow Wilson (1856–1924)
“The safety of the republic being the supreme law, and Texas having offered us the key to the safety of our country from all foreign intrigues and diplomacy, I say accept the key ... and bolt the door at once.”
—Andrew Jackson (1767–1845)
“Can we not teach children, even as we protect them from victimization, that for them to become victimizers constitutes the greatest peril of all, specifically the sacrifice—physical or psychological—of the well-being of other people? And that destroying the life or safety of other people, through teasing, bullying, hitting or otherwise, “putting them down,” is as destructive to themselves as to their victims.”
—Lewis P. Lipsitt (20th century)