Circuit Breakers, that little invention designed to protect your electrical circuits. The way they work is when fault levels exceed certain values for a certain amount of time they are designed to open the circuit and isolate the faulted portion and thereby maintain power to the remaining equipment on the circuit. Easy enough. However, if fault trip levels are reached and a breaker fails to trip, the viability of the entire circuit is put at risk. Long stretches of the breaker operating in either the open or the closed position will age or harm a circuit breaker. Trip units age, contacts pit and burn, operating mechanisms get stiff. The best hedge against these aging effects is good preventative maintenance as you might have guessed. And as you also might have guessed, here at Midwest Electrical Testing we perform breaker testing and maintenance.
No one knows the value of good maintenance more than maintenance people. If you've ever had a circuit go out due to a defective breaker, you know it's something to be avoided. The costs involved in terms of safety, equipment replacement, and down time can be staggering. Sound engineering practice sees the value of performing a risk-benefits analysis on activities that carry a cost to see if money can be better spent elsewhere. The results usually show vast improvements associated with good maintenance. But as often is the case, real world circumstance doesn't always allow for such luxury. Budgets get squeezed, priorities get changed, production schedules jam up. So where does that leave the prudent minded maintenance professional. Out in the dark? Not so fast. There are things one can do to minimize the risk of putting-off breaker maintenance programs.
Exercising or operating the breaker (a minimum of 10-15 times), as simple as that may sound, is a proven technique to keep the mechanics of your breaker running smoothly and help stave off the bad effects of idleness. Breaker contacts are designed to "wipe" themselves while closing. As the breakers closes, a slight lateral action occurs between breaker stationary and movable contacts as they come into contact with each other. This action cleans contact surfaces. Exercising the breaker also keeps current carrying pivot points in good shape. On the extreme, we've seen breakers whose mechanisms have become so stiff from lack of exercise they failed to open when tripped.
The opening and closing procedure can often be scheduled to be performed during planned extended outages or during "slack times" or "window of opportunity times."
Happy exercising.