Start of Protection Systems

When circuit breakers were first developed, engineers started to find out how to trip them automatically if short circuits occurred in distribution and generation assets. The initial approach was to interrupt short circuit currents however this technique subsequently evolved to satisfy the requirement for selective tripping of the asset. Past research into frequent explosions of oil circuit breakers has shown that breakers experience problems both in situations where the fault was cleared too quickly and in situations where there was too long a delay in tripping. Moreover, the assets being protected had thermal ratings that constrained their operation under fault conditions.