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ABB Circuit Shield Undervoltage relay

Discussion in 'Troubleshooting and Repair' started by Jack-Elec-Forum, Jan 4, 2021.

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  1. Jack-Elec-Forum

    Jack-Elec-Forum

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    Jan 4, 2021
    Anyone using ABB Circuit Shield under voltage relay? We have many of them and lately 2 of them mis-operated causing significant lost to our manufacturing process. Relay contact operated like if we had a power loss but no where in the distribution system our power quality meters detected such under voltage conditions. The relays are about 10 years old and the manual does NOT recommend any maintenance. Environment is temperature controlled.
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

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    Nov 17, 2011
  3. Jack-Elec-Forum

    Jack-Elec-Forum

    2
    0
    Jan 4, 2021
    Thanks for your quick reply. Yes one of the relays was tested as per ABB manual and we did not find any issue. The relay was also well calibrated. One aspect brought out is the pin that is inserted into the hole for the under voltage setting. If there is some sort of bad contact, the relay may default to the 120V setting (100% of nominal voltage). In such cases, anything under the nominal voltage initiates the output contact to change state.
     
  4. Harald Kapp

    Harald Kapp Moderator Moderator

    11,655
    2,696
    Nov 17, 2011
    You may try to clean the contact(s) for the pin you mention. However, this is likely only a temporary solution. If the surface of the contacts is corroded, cleaning these may restore contact but the surfaces will soon corrode again and the issue will reappear..
    Weigh the loss in the factory due to a malfunction of the relay against the cost of a new relay (or relays) and decide which way to go. You may even be able to get a rebate from the vendor of the relays if you turn in the old relay(s).
     
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