The Bowden CONTACT TIMER is a compact and easy to use hand held instrument, which enables distribution engineers to identify the slow operating mechanism before the circuit breaker is called on to operate under fault conditions.
One of the most important functions of a distribution circuit breaker is to interrupt fault current quickly in order to minimise stress on the system and associated equipment. It is equally as important to minimise the circuit breaker closing time for similar reasons especially under onerous fault conditions.
Engineering experience and supportive field trials have shown that some circuit breakers may have an unacceptably long opening time when called on to operate after they have remained closed for long periods of time.
One cause of this partial seizure in the mechanism could arise as a result of the evaporation of solvents from lubricants, which leave behind a highly viscous deposit. Other contributory factors can be corrosion, the accumulation of dust or wear on moving parts.