To Settle a Small Argument

The whole idea of a stored energy mechanism is that you are ready to close at any time. So, i would leave them charged.

Now why would your friend leave them uncharged? Long-term creep phenomenon. Quite sensible. As to 'if he is asked to close the CB suddenly ?', it rarely is a sudden phenomenon.Charging may take 4 - 10 secs, so that is also not a big deal in most cases.

However, in keeping with the principle of the thing, i design springs which are not stressed more than 75% of the permissible stress limit. Have kept them compressed solid (more than what happens in the product) for months. And found no creep.

The breakers aren't equipped for remote closing. A couple of seconds doesn't really matter.

Is the spring charging and/or closing/tripping effected manually or by electrical means?

Purely mechanical. So to my thinking, why leave a mechanism under unnecessary strain.

i would agree with you, since i may not have designed the springs in your CB

Seriously, though, with no motor charging and no remote closing, absolutely no point in keeping the springs charged.

i have also observed a curious phenomenon...

1. Springs in German products are the best-designed.

2. French and Japanese designs tend to use tension springs, where chances of hook failure are high.

3. English CBs, while overdesigned everywhere else, have the most critically designed springs. Very close to the stress limit.

Due apologies to all the designers of all these countries before my head gets bitten off....

For the breakers to be kept "OFF" for longer duration (such as bus couplers, idle feeders and standby feeders )I have always advised my substation staff to keep the "spring discharged" considering the safety reasons. It is always convenient and fast to operate a charged breaker.

But in case of a breaker kept off for a longer duration specially in case if the breaker controls supply to under ground cables ,the breaker is not charged before an insulation test is carried out ,as per safety norms. So if the breaker is charged it may cause accidental operation while pre charging insulation test is carried out.

It can also save any accidental closing by an absent minded switch board operator. Once he has to charge and close he will be more cautious and chances of accidental closure will be avoided. For a breaker which is kept off for longer duration it is always advisable to draw it out and make visual check / insulation check before closing. It is also not good to draw out and in a charged breaker.