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Helpful tips for testing Siemens SB-EC trip units (SBS circuit breakers)

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    Helpful tips for testing Siemens SB-EC trip units (SBS circuit breakers)

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    Siemens SBS circuit breakers come equipped with many different styles of trip unit, each utilizing a different means of supply power. The Sentron Energy Communicating Trip Unit (SB-EC) is the high-end microprocessor model which requires the SBEPS external power supply in order to activate the communications function and display screen.

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    You can secondary injection test using the TS31 test kit without the power supply but you won’t be able to interface with the trip unit (i.e. change settings, reset logs, etc.) during the test. Primary testing is the same story, the protective functions of the trip unit are powered by the CT’s but without the power supply you can’t change settings, nor can you defeat ground fault.

    Click image for larger version. 

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    The SBAPM power supply typically used with SB circuit breakers (shown above) will not work with this trip unit.



    How to power up the SB-EC trip unit without the SBEPS power supply

    You can power the trip unit using a simple 5VDC and 12VDC source. Wires should be located on the right side of the breaker. In this example we are working with a SBS1212.

    Click image for larger version. 

Name:	wiring-diagram-1.png 
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    +5V to RT1 (+5V Red)
    -12V to RT3 (-12V Green)
    GND to RT4 (COM Black)
    +12V to RT2 (+12V White)
    (PDF wiring diagram is attached to this post)



    How to tell which SB Energy-Comm trip unit model you have

    SBxxTP01 - Basic protection and power measurement
    SBxxTP01G - Basic plus ground fault protection
    SBxxTP02 - Advanced protection, power measurement and harmonics
    SBxxTP02G - Advanced plus ground fault protection
    Attached Files Attached Files

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    Defeating Ground Fault

    Quote Originally Posted by SecondGen View Post
    Click image for larger version. 

Name:	siemens-sbs-circuit-breaker.PNG 
Views:	472 
Size:	258.2 KB 
ID:	176

    Siemens SBS circuit breakers come equipped with many different styles of trip unit, each utilizing a different means of supply power. The Sentron Energy Communicating Trip Unit (SB-EC) is the high-end microprocessor model which requires the SBEPS external power supply in order to activate the communications function and display screen.

    Click image for larger version. 

Name:	Untitled2.png 
Views:	385 
Size:	234.6 KB 
ID:	173

    You can secondary injection test using the TS31 test kit without the power supply but you won’t be able to interface with the trip unit (i.e. change settings, reset logs, etc.) during the test. Primary testing is the same story, the protective functions of the trip unit are powered by the CT’s but without the power supply you can’t change settings, nor can you defeat ground fault.

    Click image for larger version. 

Name:	wrong-type.jpg 
Views:	382 
Size:	29.8 KB 
ID:	174
    The SBAPM power supply typically used with SB circuit breakers (shown above) will not work with this trip unit.



    How to power up the SB-EC trip unit without the SBEPS power supply

    You can power the trip unit using a simple 5VDC and 12VDC source. Wires should be located on the right side of the breaker. In this example we are working with a SBS1212.

    Click image for larger version. 

Name:	wiring-diagram-1.png 
Views:	29 
Size:	33.0 KB 
ID:	175

    +5V to RT1 (+5V Red)
    -12V to RT3 (-12V Green)
    GND to RT4 (COM Black)
    +12V to RT2 (+12V White)
    (PDF wiring diagram is attached to this post)



    How to tell which SB Energy-Comm trip unit model you have

    SBxxTP01 - Basic protection and power measurement
    SBxxTP01G - Basic plus ground fault protection
    SBxxTP02 - Advanced protection, power measurement and harmonics
    SBxxTP02G - Advanced plus ground fault protection

    How do you defeat ground fault with the analog style TU?

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