Noreco again!

Great if you can do zero-cross switching that way. The scope if triggered properly can show the two traces easily enough, then turn off trace B and turn it on again exactly in phase with trace A. You have to do that electronically because nobody can react within 16 Marc. If you do that electronically you have a zero cross switch in which case you don’t need the scope except to verify the switch worked properly. Electronic zero cross switches are not complicated and they just use a thyristor to switch on at zero cross point. But for NORECO to extrapolate that to switching on entire substation in a millisecond is quite complex.


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The article is interesting and I agree with it, especially for commercial systems. Forget about incandescent light bulbs as they can survive big surges. Electronic equipment is different; it doesn’t do well with power being instantly removed and re-energized due to the inrush of current (not voltage) destroying various components. Surge protectors do not affect that but they do protect against the other characteristic of PLD, over voltage. For residential surge protectors, I have usually seen devices that use MOV type components that clip high voltages coming into the service through lightning. This is fine as long as the over voltages are not so high as to destroy the MOV components which are actually rated in terms of the energy they can withstand. If that rating is exceeded by a very close lightning strike, the over voltage comes through and perhaps worse, they now become “resistors” and dissipate the heat of the line voltage and can create a fire (I have encountered this a few times in my work). For that reason I do not use them. If the overvoltage makes it through the regulator and the UPS, then my equipment is finished. In my case, I have seen several TV’s and even a regulator get destroyed at our place in Siquijor until I actually moved there after retiring. Dumaguete seems to be more benign and I don’t know why that is, perhaps fewer brownouts.


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I witnessed a transformer blow the other week, within 10 minutes a man on a motor bike turned up. He must have taken the box number to inform the maintenance team. They were there within 25 minutes and fixed the fuse so not so bad. I have a battery with a charger/inverter back up which keeps a few appliances going it cost around 14k peso delivered it also has a power surge protector built in.