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  1. JBirch

    Power Transformer Dispersion Testing

    Ah ha. Thankyou very much for the answers! Given our client has requested dispersion testing be performed only if other testing fails, and the other testing includes DDF (or DLA) I guess they are really asking for either RVM or PDC/FDS. This is good news as we now know we can indeed to the...
  2. JBirch

    Power Transformer Dispersion Testing

    G'day all, We have been asked to perform 'dispersion testing' on a power transformer by a client. However, until today we had not even heard of this? I have tried to search for some idea of what is involved but cannot find any relevent information. Does anyone know what this is and what it...
  3. JBirch

    Earthing System Impedance

    All step and touch reading were well within the accpetable limits. Its just the EGVR that we are concerned about... Its seems very high at ~42kV with a worst case fault clearance time of 1 second. However, as this station is not the source all fault current would be returning to the remote...
  4. JBirch

    Earthing System Impedance

    The station consists of 110kV 3 phase Over Head Transmission Lines with NO Over Head Earth Wire (OHEW) or OPGW. Hence all earth fault current must return via earth. We performed a soil resistivity test, not exactly sure what is meant by soil treatment though. The surrounding land is...
  5. JBirch

    Earthing System Impedance

    Test leads were run out to a distance greater than 10x the diagonal dimension of the earth grid. Same test method as used every other time where results have always been acceptable... Line to ground voltage of 110kV / sqrt3 (~63.51kV. Its a relatively small switching station with no TX. Only...
  6. JBirch

    Earthing System Impedance

    We recently conducted an earthing audit of a local substation. Part of the testing was fall of potential testing to determine overall ground Impedance. The measured value for this test was 10.2Ohms. This value is much higher than any other values previously measured in other locations. Due to...
  7. JBirch

    Mixing Fuels - Pros and Cons

    Being in Tassie the only 98 I have access to is BP Ultimate. However, I have read that BP Ultimate with 10% Tolulene will push the octane towards ~102... Several members of Skylines Australia have used it in High Boost applications with good results. This should work nicley in a high...
  8. JBirch

    Mixing Fuels - Pros and Cons

    I have had a look at the VP MS100 unleaded race fuel. There is a VP Fuels supplier nearish to me (about 100km away) so I will have to make some calls and see if they stock it or can get it. I am now thinking it may be a better idea to use the unleaded fuel as then I can tune the car on the raod...
  9. JBirch

    Mixing Fuels - Pros and Cons

    Thanks all for your replies. Yes, I am in Australia. A few more details: The motor is fuel injected and is using an Autronic SM4 for the EMS. There is no catalytic converter installed as it is not required for racing. The car is to be used for club days and the occasional drag race and does...
  10. JBirch

    Mixing Fuels - Pros and Cons

    G'day all, I have just completed build a Nissan RB30DE (3 ltr twin cam)with approx. 11.5:1 compression ratio. I am trying to determine what the best fuel to run this on would be. I was thinking a 50 / 50 mix of Avgas (100 RON) and PB Ultimate (98 RON). However, I am unsure of the pros and...
  11. JBirch

    Lift vs Duration

    I am looking at getting a set of cams for my Nissan 3ltr DOHC (its a combination of 3ltr block and twin cam head, not a production motor). The motor is non turbo. The main use of this car is club days, motorkhanas etc and not everyday driving. The question I have is am I better off to sacrifice...
  12. JBirch

    128Hz Bandpass Filter

    Thankyou very much to everyone for their help. There are certainly a few options to explore here. I'll do some more research with this new information and get back if I need any more help. Thanks again!
  13. JBirch

    128Hz Bandpass Filter

    The intended application is measuring of step and touch potentials associated with power system earth faults. We are injecting a 5A 128Hz signal into a remote earth stake and measuring the potential rise. We need to filter out any power system frequency voltages and associated harmonics. ie...
  14. JBirch

    128Hz Bandpass Filter

    Need to build / buy a 128Hz band pass filter. Having trouble finding any information regarding design, components required etc. Needs to have a gain of 1, and a bandwidth of 10Hz. Needs to be an active filter to keep losses to a minimum. Thanks heaps in advance, Jamieson

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