Recent content by Distribution73

Thank you DPC. I will do. If I manage to get some feedback I will upload to the thread.

Thank you very much Brucesilver and DPC. @brucesilver, I agree the circuit appears to seek the type of compromise you mention. However I am not sure what is the actual procedure to seize the resistors (series and transient reduction). From the substation samples I got the impression that the...

Hello, While reviewing drawings from an (old) existing substation, I have come across a number of tripping circuits where auxiliary relays (normally GE HFA51A type) are used in an arrangement I cannot quite understand. These auxiliary relays are used in Busbar Diff and CBF circuits, where...

I am having certain difficulty to understand how the delay Line of the TRV envelope curves specified in standards such as IEEE Std C37.04 is to be interpreted against a prospective TRV for a breaker in a substation. In the standards ( for example IEEE C37.04) it is explained that this line...

Wonderful link dpc. Thank you for sharing.

Thank you very much Scottf.

Hello, When several sets of current transformer are mounted on a bushing I have seen them marked as X, Y,(Z, W ...). However it is unclear to me what is what are the relative position of these marking within the bushing. That is: I have seen manufacturer drawings (for CBs with bushing CTs) where...

Thank you very much for your feedback cranky108 and bacon4life. Based on these replies and what I have read elsewhere I think that I will have to seek confirmation of the breaker capabilities from the supplier anytime I encounter a reclosing sequence that exceeds two shots. Thanks again for the...

Hello, I can see that the standard duty cycle for circuit breakers is well documented and can be found for example on the breaker nameplate. However this standard rating appears to cover two closing operations. What is unclear to me is what happens when we reach the last "open" of the sequence...

Thank you very much. That is very helpful information.

Hi, I am trying to replace an old analog voltmeter installed in a synch panel. The reason for doing so is that the ratio of the VT connected to this device has changed. I would like to replace it by another one as similar as possible to the original. Going through different catalogs of analog...

Thank you very much for the all the info. It is very helpful.

Thank you very much cranky108 and waross for the great feedback. What we are trying to achieve in our case is to segregate a trip branch so that we can monitor it. I think the sketch will clarify more than my words: What we are trying to do is to "Monitor" the operation of Tripping Contact...

Hi, I would appreciate it very much to know your opinions on the following subject: We are modifying an existing electromechanical busbar tripping circuit, and we would like to segregate the new trip contacts by means of a blocking diode. The control voltage is 125Vdc. The new tripping branch we...

Hi, In some of the projects I have been involved, our customer has advised us to use another factor when rating bushing CTs using a tap less than its maximum. The formula they have asked us to use is: CT Thermal Rating = Rating_tap_used x (sqrt(Rating_max_tap / Rating_tap_used)) x RF That is: If...