Quote:
Originally Posted by APS
The main power feed into our building has a three phase lightning protector (Bowthorpe DSP600) connected directly to the main power ground coming in with the supply. It is not indicating a fault after the strike.
|
The Bowthorpe's failure indicator only reports when a protector was grossly undersized. It will not report other failures. According to specs, it should be functional.
Matters little how far away. A strike 200 meters away may be electrically same as another only 5 meters away. We expect protection to make even lightning irrelevant since most other surges typically cause no damage. Due to superior protection routinely found in appliances (see the previous VQ301 discussion).
So, did a surge enter on AC electric? Depends on what was most important. Not the Bowthorpe. How was a Bowthorpe connected to earth. Since earth ground does the protection (not the Bowthrope). For example, that connection must be low impedance (ie 'less than 3 meters', no sharp wire bends, separate from other non-ground wires, etc). And it must be single point earth. Not a single point ground in the IT room (which is electrically different). A single point earth ground.
If earthing is done properly, ground bounce causes no problem. Single point ground means everything bounces to the same voltage. No voltage difference means no voltage between any incoming and outgoing wire. The bounce could be 2000 volts. Since all wires are at 2000 volts, then no voltage appears on any appliance.
Many only assume a magic box will solve surges. It doesn't. The Bowthorpe, like all protectors, is only a connecting device. If a ground is not single point, then voltage differences exist inside. From anything - ground bounce or between any other utility wires. Even the cable must connect low impedance (ground wire has no bends) to that single point earth ground.
This much you know. A current was incoming on one wire. And outgoing from the router, et al on some other wire. That current does not exist if all wires in every incoming cable were first connected low impedance to the same earth ground.
So what wire entered the building without a low impedance connection to single point earth ground? That could be the incoming path. What wire was properly earthed? That could be the outgoing path. Appliance damage often happens on its outgoing connection.
A utility demonstrates the problem and solutions:
http://www.duke-energy.com/indiana-b...ech-tip-08.asp
If your protection system does not protect from lightning, then it is only protecting from surges that typically cause no damage. Protection is about destructive surges including lightning.
A direct strike to buried wires 200 meters down the street could be a direct strike to all interior equipment. Is everything damaged? Of course not. Damaged is equpiment that also made a best outgoing connection to earth.
An investigation asks where the human made a mistake. Starts with the earthing system. Does every incoming wire make that low impedance (ie 'less than 3 meter') connection to earth? A connection via a hardwire or via a protector? If not, protection was compromised and earthing must be fixed. Even telco wires must be earthed back at or near the master socket.
If a wire from VQ301 is 10 meters to earth ground, then the VQ301 is not earthed. And, as another noted, that connection may also cause other complications.
Those APCs have near zero protection. Read their numbers. Those UPSes have one purpose - to provide temporary and 'dirty' power to computers. Read its specs. As noted earlier, those UPSes only provide protection in hearsay. To provide protection, each must have a low impedance (ie 'less than 3 meter') connection to the single point earth ground. Protection superior to that UPS is routinely in computer power supplies. If an APC does actual protection, then you can post the spec number that says so. For example, how many joules will it absorb?
Join CF
You are here: 
