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Time curves for ETU745 & 766

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    Time curves for ETU745 & 766

    We are needing to do primary injecting testing on some Siemens WL breakers with an ETU745 & 766 trip unit. I have searched the internet and I canít seem to find any curves for the units.

    Also, I think to override the ground fault I need to jump pins 9 & 10 on 8X?

    Any help would be appreciated.


    Thanks
    Dave.

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    Quote Originally Posted by Dave32 View Post
    We are needing to do primary injecting testing on some Siemens WL breakers with an ETU745 & 766 trip unit. I have searched the internet and I canít seem to find any curves for the units.

    Also, I think to override the ground fault I need to jump pins 9 & 10 on 8X?

    Any help would be appreciated.


    Thanks
    Dave.
    For that trip unit, I think you need to download the Siemens Time Current Curve (TCC) Software. Once installed, you can fill out the breaker info and trip unit settings and it will generate the curve for you.

    http://w3.usa.siemens.com/powerdistr...-software.aspx

    You might find the software a bit difficult to use, its outdated and not designed very well. As for ground fault, if I remember correctly on that trip unit you need to change the ground fault sensing scheme to source ground when primary injection testing, this looks at current on the neutral sensor only.

    I'm having trouble finding the specific manual for you trip unit. Some models have a switch, others have a jumper that can only be changed by removing the trip unit.

    Click image for larger version. 

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    Quote Originally Posted by Dave32 View Post
    We are needing to do primary injecting testing on some Siemens WL breakers with an ETU745 & 766 trip unit. I have searched the internet and I canít seem to find any curves for the units.

    Also, I think to override the ground fault I need to jump pins 9 & 10 on 8X?

    Any help would be appreciated.


    Thanks
    Dave.
    This is the manual that answers your question, a little late, but good for anybody else:

    https://docs.natlswgr.com/docs/W1000570.pdf

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    What do you use to power up a ETU 776 trip unit out of the cubicle?

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    Quote Originally Posted by oarreola View Post
    What do you use to power up a ETU 776 trip unit out of the cubicle?
    If I remember right (its been years since I had to do this), you can supply 24Vdc to X8 terminals 3(+) and 4(-). That being said, you need to verify you have a true filtered dc power supply, or it can fry the ETU trip unit.

    Click image for larger version. 

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    Quote Originally Posted by Kalbi_Rob View Post
    If I remember right (its been years since I had to do this), you can supply 24Vdc to X8 terminals 3(+) and 4(-). That being said, you need to verify you have a true filtered dc power supply, or it can fry the ETU trip unit.

    Click image for larger version. 

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    What would be the best way to filter the dc supply?

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    Quote Originally Posted by oarreola View Post
    What would be the best way to filter the dc supply?
    If your power supply has a DC regulator, it will have a pure DC output. If your using a power supply that uses a bridge rectifier with a capacitor, it could produce a ripple DC output. A ripple DC output can be used, but if the capacitor starts to fail, the ripple can become larger and damage sensitive DC equipment.

    Thus, you need to know what kind of power supply you have based on manufacturer drawings. If you don't know, then your better off using the Siemens secondary kit, or powering up the switchboard CPT which powers up the equipment DC power supply.

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    Quote Originally Posted by oarreola View Post
    What do you use to power up a ETU 776 trip unit out of the cubicle?
    Siemens Secondary Kit, would recommend renting if you don't need it often.

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    Thanks guys!

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    ETU 745 Primary Injection

    I just performed primary injection testing on a WL type Siemens breaker with a ETU 745 trip unit.
    The only way that I know of to obtain the time current curve is with their (Siemens) curve plotting software, Easy TCC.

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