Dar measurement of breaker
You're referring to the "Dar" measurement of a breaker!
In the context of electrical breakers, "Dar" is an abbreviation for "Dissipation Arcing Resistance". It's a measure of the resistance to arcing that occurs when a breaker is operated, such as when it trips or is reset.
The Dar measurement is typically expressed in ohms (Ω) and is used to evaluate the performance of a breaker in terms of its ability to extinguish arcing faults. A lower Dar value indicates better arc extinction capabilities, which is important for ensuring the safety and reliability of the electrical system.
In general, a Dar value of:
- 10-20 Ω or less is considered good for most applications
- 20-50 Ω is acceptable for some applications, but may not be suitable for high-voltage or high-current systems
- 50 Ω or higher may indicate a breaker that is not suitable for use in a particular application
It's worth noting that Dar is just one of several important measurements used to evaluate the performance of an electrical breaker. Other key measurements include:
- Breaking capacity (BC): the maximum current that a breaker can interrupt without failing
- Making capacity (MC): the maximum current that a breaker can carry without overheating
- Dielectric strength (DS): the ability of a breaker to withstand electrical stress without breaking down
When selecting a breaker for a particular application, it's important to consider all of these measurements, as well as other factors such as the breaker's physical size, weight, and environmental operating conditions.