Protection NOC3Inst (non-directional overcurrent 3-phase protection instantaneous stage) will trip only when voltage‘s magnitude drops below 0,5xUn (here Un is nominal voltage of PLC analogue input). Usually Un=100 V AC. Function block UV3Low (undervoltage 3-phase low stage) measures voltages.

More information about function block NOC3Inst you can find in manufacturer‘s ABB manual “NOC3_ Three-Phase Non-Directional Instantaneous Stage (NOC3Inst) 1MRS752309-MUM”, about function block UV3Low – in manual “UV3 _ Three-Phase Undervoltage Protection Low-Set Stage (UV3Low) 1MRS752333-MUM”.

More about configuration‘s principles you can find in manufacturer‘s ABB manual „Relay Configuration Tool Tutorial 1MRS751903-MEM“.

Now we‘re going to begin configuration.

1. Select project‘s object (in my case it is „IC-1“) and run „Relay Configuration Tool“ application:

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2. In project configuration tree select program unit “Protect”. Open it:

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3. Insert function block NOC3Inst:

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NOC3Inst is non-directional 3-phase overcurrent instantaneous protection. It has only definite time current charakcteristic. This means that tripping time of protection NOC3Inst is independent from current’s magnitude. Function blocks NOC3Low and NOC3High have time inverse current characteristics: tripping time shortens when current‘s magnitude increases and by contraries tripping time increases when current‘s magnitude drops.

4. Connect currents IL1, IL2 and IL3 to function block NOC3Inst as shown in picture:

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5. Create variables “NOCInstStart” and “NOCInstTrip”:

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Variable NOCInstTrip:

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6. Connect created variables “NOCInstStart” and “NOCInstTrip” to function block NOC3Inst as shown in picture:

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7. Insert voltage’s function block „UV3Low“. This protection will trip when voltage drops below 0,5xUn. By tripping UV3Low protection there will be enabling protection NOC3Inst:

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8. Insert variables U12, U23, U31 and connect them to function block UV3Low as shown in picture:

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Function block UV3Low:

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9. Insert logical block „NOT“ and connect them to function blocks NOC3Inst and UV3Low as shown in picture:

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Overcurrent protection with undervoltage blocking:

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Working principle of this protection. When current will reach current setting of protection NOC3Inst (in „Relay Setting Tool“ this is parameter „Start current“), output „Trip“ of protection NOC3Inst won‘t be activated until output „Trip“ of protection „UV3Low“ won‘t be activated (in „Relay Setting Tool“ this is parameter „Start voltage“). When function block UV3Low is not active, output „Trip“ of protection „UV3Low“ has logical „0“. Logical block „NOT“ inverts this signal to logical „1“ and this signal is inputed to input „BS1“ (block signal 1) of function block „NOC3Inst“. Always when input „BS1“ asserts logical „1“, output „Trip“ of function block „NOC3Inst“ is being blocked (even the current setting of protection „NOC3Inst“ is reached). When voltage in busbar drops below 0,5xUn, protection „UV3Low“ will trip, output „Trip“ of function block„UV3Low“ will activate, there will be logical „1“, this signal will be inverted to logical „0“ by logical block „NOT“ and in input „BS1“ will be logical „0“. And when at the same time will be reached setting „Start current“, function block „NOC3Inst“ will trip (output „Trip“ will activate).

 

More detail about function block „NOC3Inst“ you can read in manufacturer‘s ABB manual “NOC3_ Three-Phase Non-Directional Instantaneous Stage (NOC3Inst) 1MRS752309-MUM”.

 

Save configuration by selecting „File>Save“ and exit from program „Protection“ by pressing „File>Exit“.

 

 

The next step is to configure signalization: I‘m going to connect tripping of protection „NOC3Inst“ to the second LED of PLC REF543.

10. In project configuration tree select program „Signal“ and open it:

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Insert function block „MMIALAR2“:

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11. Insert already created variable „NOCInstTrip“ and connect them to function block „MMIALAR2“ as shown in picture:

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12. Save configuration and exit from program “Signal” by selecting “File>Exit”.

Compile configuration by selecting “„MAKE>MAKE“:

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13. Close „Relay Configuration Tool” application by selecting „File>Exit“. The configuration is completed.

 

 

 

Now we need to set parameters of protection „NOC3Inst“ by using „Relay Settings Tool“ application.

14. Start „Relay Settings Tool“ application:

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There are function blocks „NOC3Inst“ and „UV3Low“:

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Now we‘re going to define parameters of these function blocks.

15. Select “Protection>NOC3Inst>Setting Group1” and set parameters as shown in picture:

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16. Select “Protection> NOC3Inst >Control setting” and define settings as shown in picture:

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Settings of events:

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Other settings leave as default.

17. Select “Protection> UV3Low >Setting Group1” and set parameters as shown in picture:

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18. Select “Protection> UV3Low >Control setting” and define settings as shown in picture:

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Event list‘s settings:

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Others settings leave as defaults.
19. Save defined settings by selecting „YES“:

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20. Connect tripping signal „NOCInstTrip“ to second LED by using “Relay Mimic Editor”.
Open “Relay Mimic Editor” tool:

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21. Press button “Alarm LED Texts in “Relay Mimic Editor” window and define second LED as
„NOCInstTrip“:

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LED‘s state define as „Latched, steady“.

22. Save settings by pressing “OK”.
Close “Relay Mimic Editor” tool by selecting “File>Exit”.

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Press “YES”:

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23. Sending of configuration to PLC REF543.
Open „Relay Download Tool“ application:

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Select options as shown in picture and press „Send“:

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Configuration and mimic have been sent successfully.

24. Sending of settings to PLC REF543.
Open “Relay Setting Tool” application:

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Select button „Download“:

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Send all settings to download to PLC REF543:

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Save downloaded settings to EEPROM memory:

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25. Close „Relay Setting Tool“ application by selecting „File>Exit“.

 

 

 

Now we‘re going to test protection NOC3Inst with UV3Low blocking.

 

 

26. Settings of protection „NOC3 Inst“: I=0,8xIn=0,8x5A=4A.

Settings of protection UV3Low: U=0,5xUn;

Supply currents and voltage from testing equipment:
Ia=4,1A, IB=4,1, Ic=4,1A. φa=0˚, φb=240˚, φc=120˚.
U12=49V, U23=49V, U31=49V; φa=0˚, φb=240˚, φc=120˚.

 

Testing principle scheme is the same as used in article no. 11 “CAP505: Testing measurements“:

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Inject currents and voltages from testing equipment:
Ia=4,1A, IB=4,1, Ic=4,1A. φa=0˚, φb=240˚, φc=120˚.
U12=49V, U23=49V, U31=49V; φa=0˚, φb=240˚, φc=120˚.

Data on HMI of PLC REF543:

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The second LED is indicating tripping of protection „NOC3Inst“:

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Measurements on HMI‘s „Measurement“ window:

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„BS1“ of function block „NOC3Inst“ is not active:

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27. Now we are going to test blocking of protection „NOC3Inst“ from undervoltage protection „UV3Low“.

 

Testing scheme is the same as used in particle no.26 of this article.

 

Inject currents and voltage from testing equipment:
Ia=4,1A, IB=4,1, Ic=4,1A; φa=0˚, φb=240˚, φc=120˚.
U12=100V, U23=100V, U31=100V; φa=0˚, φb=240˚, φc=120˚.

 

Protection did not trip although setting „Start current“ of function block „NOC3Inst“ is reached (I>0,8xIn):

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Measurements on HMI‘s window „Measurement“:

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„BS1“ signal of function block „NOC3Inst“ is“ active, therefore the protection „NOC3Inst“ is blocking:

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Conclusion:
The protection „NOC3Inst with UV3Low blocking“ is configured correctly and is working reliable.

 

 

Int the next article I‘ll demonstrate how to configure circuit breaker failure protection (CBFP) invoking from protections „NOC3High“ and „NOC3Inst“.