surge protection

Discussion in 'Electricians' Talk' started by Lectric man, Nov 13, 2003.

  1. Lectric man

    Lectric man New Member

    what do you think would be the most cost effective way to provide surge protection to a computer suite of about 20 computers and associated equipment. Also I understand the special requirements for dual earth sockets and for the earths to be terminated in seperate terminations in the consumer unit including the ring cpc,and that the cpc becomes "funtional to discharge current from the PC'S but what practical function does seperate earth terminals have. Hope this makes sense

    Always willing to learn LM
     
  2. I think clean earth helps keep expensive and sensitive equipment alive for longer. What is the answer to his question though?? I'd like to know.
     
  3. pachyderm

    pachyderm New Member

    A few years back I was responsible for setting up computer systems off the beaten track in Africa, South Asia and South America. I've been racking my brains for details of the UK based suppliers we used and the been trying to identify the current (no pun intended) equivalents of the equipment we used to use. However there appears to have been a great many changes in the intervening time.

    In looking around I came across the following which may be of use to you:

    http://www.aelgroup.co.uk
    - took over Galatrek, (one of the suppliers of equipment we used). Apparently they sold off the UPS manufacturing side and now concentrate on power protection.

    http://www.voltexelectronics.com
    - Only know what's on their website, but it might do depending on the degree of protection you're looking for.

    We tended to protect everything with FRLCs or UPSs incorporating FRLCs. Sometime we had MOV surge arrestors fitted also. In the more remote locations we used solar power or rotated batteries with the vehicles.
     
  4. ban-all-sheds

    ban-all-sheds New Member

    I think the separate earth is to stop the earth leakage that computer PSUs are plagued with (ironically due to their own inbuilt surge protection measures) from tripping the RCD.

    If you're interested, here's the why: http://www.tlc-direct.co.uk/Book/7.8.1.htm

    and here's how your it should be wired: http://www.tlc-direct.co.uk/Book/7.8.2.htm


    Finally, I'd suggest that an installation that has 20 PCs plus associated stuff probably deserves a UPS.
     
  5. pachyderm

    pachyderm New Member

    Good references BAS.
    UPS for server - certainly. UPSs for other equipment only if its use warants it. Most of the basic UPSs sold for computer equipment does not protect against surges (hence our use of FRLCs).
    Just a minor issue with your first statement - seperate earth is not so much to stop the earth leakage, rather to allow it! - The switched mode PSUs need the earth to dissipate some types of line interference.

    I had first hand experience of this a few years back. Telephone call on a Wednesday morning to say the "system" (a pre-PC multi-user, multi-processor micro) had failed, and an external consultant was flying in on Sunday to install new software and train users. Was able to diagnose PSU failure quite quickly, but was unable to get a replacement in my hand until the following morning. Thursday evening jumped onto an overnight flight with spares tools and clothes all in hand luggage. Hand luggage only mant that I was able to change connecting flight to one leaving just 15 minutes after I arrived at my transit airport. Walked into the office just before lunch on Friday. Replaced the PSU - system worked OK - breathed a sigh of relief. Thirty minutes later new PSU blew! I ten did what I should have done earlier and checked the power distribution from the UPSs - the Earth was "floating" - a local electrician had decided not to bother reconnecting it after installing a new circuit. So after reconnecting and testing the Earth I had to scour the local market for a PSU with the required output then connect this up from outside the box of the computer. This gave enough time to have a beer with the incoming consultant on Sunday evening and make sure all was well on the Monday morning before heading to the airport. Early morning arrival back in the UK on Tuesday morning and back into the ofice for 9.30 (it was on the way home). Why was I not believed by those who asked if I'd done anything interesting over my long weekend when I told them I'd been to Kathmandu?
     
  6. ban-all-sheds

    ban-all-sheds New Member

    Good job your emergency mission happened a few years ago - can you imagine trying to get onto a plane today with tools in your hand luggage?

    And what must a PSU look like in an X-ray machine?
     
  7. pachyderm

    pachyderm New Member

    Good job your emergency mission happened a few years
    ago - can you imagine trying to get onto a plane
    today with tools in your hand luggage?

    It scares me to think about it - The trip was a shortly after the Lockerbie bomb. My return flight from Delhi to London via Franfurt was with PanAm. I carried back the two failed PSUs and a friends large shortwave radio. I had bought a carpet while there. For my flight from Kathmandu to Delhi I checked in the holdall and hand carried the carpet. Hand luggage (the carpet) was x-rayed while the holdall was not checked. In Delhi I was reunited with the holdall and decided to check the carpet in and carry the holdall. When it went through the x-ray machine the policeman was not looking at the screen. At the boarding gate they had an additional x-ray machine (extra security because of the bomb). Most people were required to have their hand luggage x-rayed, but I was waved straight through. We had to disembark at Frankfurt, when queueing to reboard the plane a member of PanAm staff was asking each passenger if they had battery powered equipment with them and if so could she examine it. She then took at the batteries and returned it, with the batteries to the passenger. When she asked me I told her I had a radio, but it had no batteries in it. She said OK and went on to the next passenger.
     

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