Results 1 to 3 of 3

Thread: COC including supplies from UPS

  1. #1
    Full Member
    Join Date
    Oct 2012
    Location
    Durban
    Posts
    66
    Thanks
    0
    Thanked 5 Times in 4 Posts

    COC including supplies from UPS

    I would be interested to hear how members of this group are carrying out COC's for UPS feeds. I seem to be getting more of these all the time now. All of them are in industrial environments and sometimes involve the UPS feed to a DB or a feed from the UPS DB to 230V instruments in the filed.
    My biggest concern is the PSCC and ELI.
    There aren't any fault levels marked on the UPS. I presume that this would in any event change according to the amount of batteries installed.
    I have heard people say that in the event of a fault the inverter will switch back to mains so therefore test the mains circuit to get the values however, this still presents problems in getting the readings.

    Second question is testing of 525V feeds from MCC's to motors etc. I have one at the moment where I am to issue a COC for a 525V feed from MCC to 0.4KW motorised valve. My tester cannot test this voltage even though it will be 303V phase to earth. I am trying to get the engineers to give me the PSCC at the MCC but from previous experience they will give me the main switch kA rating and not the actual PSCC. Anyone else had these problems.

  2. #2
    Platinum Member
    Join Date
    Jun 2017
    Location
    Port Elizabeth
    Posts
    1,266
    Thanks
    34
    Thanked 308 Times in 260 Posts
    The fault levels on a UPS will be the max level it will hold an inrush for which is generally at 1,5 times nominal - Is often on the rating plate.The fault level is low due to the electronics that will cut the system out on a short circuit.

    You can use the incoming mains fault level which will generally be higher than the UPS.

    The batteries have no influence on the 220v side fault levels - The internal fault level on the batteries within the machine is a different story but not relevant to us
    Same as a generator .The fault level will never be more than 1,5 times rating . If you double the load on a genset it just " dies"

  3. #3
    Full Member
    Join Date
    Oct 2012
    Location
    Durban
    Posts
    66
    Thanks
    0
    Thanked 5 Times in 4 Posts
    Quote Originally Posted by GCE View Post
    The fault levels on a UPS will be the max level it will hold an inrush for which is generally at 1,5 times nominal - Is often on the rating plate.The fault level is low due to the electronics that will cut the system out on a short circuit.

    You can use the incoming mains fault level which will generally be higher than the UPS.

    The batteries have no influence on the 220v side fault levels - The internal fault level on the batteries within the machine is a different story but not relevant to us
    Same as a generator .The fault level will never be more than 1,5 times rating . If you double the load on a genset it just " dies"
    Thank you for the feedback. I have spoken to UPS manufacturers and installers of major equipment and none of them have told me that. I will use that in future.

Similar Threads

  1. Fuel supplies.
    By JohnW1234 in forum South African Politics Forum
    Replies: 6
    Last Post: 23-Dec-21, 10:45 AM
  2. alternate supplies
    By ians in forum Electrical Contracting Industry Forum
    Replies: 1
    Last Post: 31-Jul-20, 12:29 PM
  3. Replies: 1
    Last Post: 06-Apr-13, 08:01 AM
  4. Replies: 3
    Last Post: 12-Jan-12, 09:26 PM

Did you like this article? Share it with your favourite social network.

Did you like this article? Share it with your favourite social network.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •