Surge protection 1

[rusape]

I have been asked by my company to investigate and make recommendations with regards to voltage surges on our plant.
I do not have alot of experience with this kind of thing and was hoping if someone might have some knowledge, experience with this, or know of a good web site to get the relavent information. What I need to know is the following:
1. causes of voltage surges
2. things to look at to identify if it is a problem
3. where to put the surge protection if needed
4. Best kind, worst kind of protection
5. Earthing of the system to illiminate ground loops.

The in-coming voltage is stepped down to 525V which goes
to the main board where the neutral is earthed to the earth bar which is connected to a ground stake. The plant has many plc's, soft starters, vsd's and DOL's.

 

[Skogsgurra]

I would start the whole thing by getting some basic information. It is a cyclic experience where measurements play an important role. You can do very well with an ordinary digital oscilloscope for your preliminary studies. But you should think about buying or hiring a dedicated analyser (like Dranetz or similar).

You will also need to have access to - and understand - the standards that apply. It usually takes some time to understand what they are about and how to interpret them. Allow plenty of time for this. Find out if your mains voltage seems to be within limits or not. Make notes about which hours and minutes there seems to be problems.

Arm yourself with a single line diagram showing what your 525 V distribution looks like. Transformer and capacitor data. Where heavy loads and sensitive loads are and so on.

Interview people that have (mains voltage) problems with their equipment. Ask them how often, when, how they make things work again (reset, repair, other). Compare their answers with your notes about mains surges and transients.

I could go on for quite a while with this. But it is lunch time so I leave it like this for a while.