Zone Selective Interlocking (ZSI)

Transcription

1 Zone Selective Interlocking () Functionality and Structure of For short circuit and ground fault as well Application Guide

2 Selective tripping? Objective: Selective tripping with minimum short-circuit duration, irrespective of the grading level in which the short-circuit occurs. Selectivity: A system with several protective devices connected in series is referred to as selective if - in the event of a shortcircuit - only the protective device (example: Q22) located directly in front of the fault location responds and clears the short-circuit by itself. Unaffected branch circuits continue to be supplied. -Q11 -Q21 -Q22 -Q1 -Q2 -Q Page 2

3 Selectivity achieved via the short-time delayed short-circuit release T kva Q11 WL1 + 5B In = 2,500A Q21 WL1 + 5B In = 1,600A Q1 WL1 + 5B In = 1,250A Q1 WL1 + 5B In = 800A Q51 WL1 + 5B In = 60A Ikmax = 9.9 ka Ikmin = 1.1 ka Ikmax =. ka Ikmin = 25.8 ka Ikmax = 0.8 ka Ikmin = 21.1 ka Ikmax = 27. ka Ikmin = 17. ka Ikmax = 21.2 ka Ikmin = 11.6 ka Settings for WL1 with ETU5B I sd t sd I i (12*I n =) ms OFF 0 ka 00 (12*I n =) ms OFF 19.2 ka 00 (12*I n =) ms OFF 15 ka 00 (12*I n =) ms OFF 9.6 ka 200 (12*I n =) ms OFF 7.56 ka 100 Solution: Example of time grading using a WL1 The WL is given a different delay time t sd in the individual grading levels. The objective is to delay the tripping of the upstream circuit breakers for the short-circuit duration until the circuit breaker closest to the fault clears the short-circuit. Q61 KL Q62 VL + TM Q6 NP Load Load Load In = 80 A Ikmax = 1. ka Ikmin = 5.5 ka In = 160 A Ikmax = 17.0 ka Ikmin = 7.0 ka In = 50 A Ikmax = 9.1 ka Ikmin =.6 ka Page

4 Selectivity achieved via the short-time delayed short-circuit release T kva Q11 WL1 + 5B In = 2,500A Ikmax = 9.9 ka Ikmin = 1.1 ka Settings for WL1 with ETU5B I sd t sd I i (12*I n =) ms OFF 0 ka 00 Problem 1: In this example, a grading level is missing from the time grading Q21 WL1 + 5B In = 1,600A Q1 WL1 + 5B In = 1,250A Q1 WL1 + 5B In = 800A Q51 WL1 + 5B In = 60A Ikmax =. ka Ikmin = 25.8 ka Ikmax = 0.8 ka Ikmin = 21.1 ka Ikmax = 27. ka Ikmin = 17. ka Ikmax = 21.2 ka Ikmin = 11.6 ka (12*I n =) ms OFF 19.2 ka 00 (12*I n =) ms OFF 15 ka 00 (12*I n =) ms OFF 9.6 ka 200 (12*I n =) ms OFF 7.56 ka 100 Q11 and Q21 trip simultaneously The reason: a) No time grading b) No current grading possible Q61 KL Q62 VL + TM Q6 NP Load Load Load In = 80 A Ikmax = 1. ka Ikmin = 5.5 ka In = 160 A Ikmax = 17.0 ka Ikmin = 7.0 ka In = 50 A Ikmax = 9.1 ka Ikmin =.6 ka Page

5 Selectivity achieved via the short-time delayed short-circuit release T kva Q11 WL1 + 5B In = 2,500A Q21 WL1 + 5B In = 1,600A Q1 WL1 + 5B In = 1,250A Q1 WL1 + 5B In = 800A Q51 WL1 + 5B In = 60A Ikmax = 9.9 ka Ikmin = 1.1 ka Ikmax =. ka Ikmin = 25.8 ka Ikmax = 0.8 ka Ikmin = 21.1 ka Ikmax = 27. ka Ikmin = 17. ka Ikmax = 21.2 ka Ikmin = 11.6 ka Settings for WL1 with ETU5B I sd t sd I i (12*I n =) ms OFF 0 ka 00 (12*I n =) ms OFF 19.2 ka 00 (12*I n =) ms OFF 15 ka 00 (12*I n =) ms OFF 9.6 ka 200 (12*I n =) ms OFF 7.56 ka 100 Problem 2: In the event of a short-circuit, e.g. directly after Q11, Q11 must still wait for the time t sd (00ms), even though the circuit-breaker could clear the short-circuit immediately. The result is that the system is exposed to the short-circuit for an unnecessarily long time. Q61 KL Q62 VL + TM Q6 NP Load Load Load In = 80 A Ikmax = 1. ka Ikmin = 5.5 ka In = 160 A Ikmax = 17.0 ka Ikmin = 7.0 ka In = 50 A Ikmax = 9.1 ka Ikmin =.6 ka Page 5

6 Selectivity via the function? Zone Selective Interlocking () in the event of short-circuits and ground faults One possible solution to ensure selectivity for circuit breakers easily and safely is the function of the SENTRON WL and the SENTRON VL WL CubicleBus module VL COM20/21 Page 6

7 Structural principle of the function Each circuit breaker features a module The modules are connected to one another The output ( OUT), example of grading level #2, is connected to the input ( IN), example of the upstream grading level #1 modules within one grading level are connected in parallel Integration of a coupling switch is possible Integration of medium voltage is possible No configuration is required Page 7

8 Basic procedure of the function in the event of a short-circuit From the viewpoint of Q2: Short-circuit detected case a) or b) OUT Set signal! Yes Short-circuit current in the instantaneous range? No Tripping after approx. 20 ms IN Yes (case b) signal detected? No (case a) t sd = 00 ms start t = 50 ms start Tripping after approx. 50 ms Shorter tripping time via with full selectivity Yes Short-circuit still present? No Tripping after approx. 00 ms* No tripping * Applies to the reference point 12 x In. The tripping time can be longer for smaller short-circuit currents Page 8 No inherent circuit breaker times observed during the tripping

9 Basic procedure of the function in the event of a short-circuit Page Short-circuit detected! 2. Set OUT signal to upstream Q1. Check whether the short-circuit current is greater than or equal to I i (response value of the instantaneous short-circuit release)? => If so, an instantaneous tripping operation occurs. Check whether a IN signal from the downstream Q is present? 5. No IN signal present! The tripping operation occurs with the time t = 50 ms 6. A IN signal from Q detected. The time t sd = 00 ms is started 7. A check is made to see whether circuit breaker Q, which has also detected the short-circuit ( IN signal), has cleared the short-circuit. Thanks to, the tripping time of the circuit breakers, and therefore the load on the switchgear, is significantly reduced!

10 Basic procedure of the function in the event of a ground fault From the viewpoint of Q2: Ground fault detected case a) or b) OUT Set signal! IN Yes (case b) signal detected? No (case a) t g = 00 ms start t = 100 ms start Tripping after approx. 100 ms Shorter tripping time via with full selectivity Yes Ground fault still present? No Tripping after approx. 00 ms No tripping No inherent circuit breaker times observed during the tripping Page 10

11 Basic procedure of the function in the event of a short-circuit or ground fault short-circuit ON / OFF S -IN (1) -OUT (2) SD-Time Time OFF NO NO NO t SD 00 ms OFF YES NO YES t SD 00 ms ON NO YES NO t SD 00 ms ON YES YES YES t SD 00 ms ON NO NO NO t 50 ms ON YES NO YES t 50 ms ground fault ON / OFF GF -IN (1) -OUT (2) SD-Time Time OFF NO NO NO t g 00 ms OFF YES NO YES t g 00 ms ON NO YES NO t g 00 ms ON YES YES YES t g 00 ms ON NO NO NO t 100 ms ON YES NO YES t 100 ms Page 11

12 Possible applications of the function In the event of a short-circuit and a ground fault Ensuring a very short delay time with full selectivity => typically 80 ms to a maximum of 90 ms (t + mechanical tripping) in the event of a short-circuit t = 50 ms (delay time) in the event of a short-circuit t = 100 ms (delay time) in the event of a ground fault localizes the location of the short-circuit or ground fault Reduction of the loads / damage in the event of a short-circuit or ground fault in the system and for cables / lines Mixed system design with WL, VL, WN (not for new systems) Integration of coupling switches Integration of existing system parts (e.g. WN) Integration of the medium-voltage circuit breaker directly in front of the transformer Use in extensive, decentralized energy supply systems The "delay time" enables the integration of an additional, downstream protective device level without connection, provided that instantaneous tripping occurs Page 12

13 Benefits and advantages of the function Selective tripping for minimum short-circuit / ground fault duration No parameterization of the function required. This prevents setting errors. Optimization of cables, since t d always = 50 ms +5 ms (S 2 k 2 > I 2 t, the requiring energy is only dependent on I 2, since t d = const. < 100 ms) (blocking) signal is also set when the instantaneous trip unit (instantaneous release) trips Only the circuit breaker directly upstream from the fault location is switched off in the event of a short-circuit and/or a ground fault Increasing the grading levels, depending on the type of trip unit and the line length (maximum number of grading levels >20 with ETU 76B and t sd up to 000 ms) Time limitation of an arc fault short-circuit current to less than 100 ms Quick tripping time of the upstream circuit breaker if the short-circuit is "skipped". module can at any time be retrofitted without difficulty, depending on the trip unit type Connection of devices without possible (lowest level, instantaneous tripping) Page 1

14 Why is it important to clear a short-circuit quickly? The effect of the short-circuit increases as time progresses Thermal load on all equipment I cw for switching devices decreases considerably as time progresses High dynamic load on the switchgear Voltage dip during faulty operation of the other consumers Risk of persons getting an electric shock (touchable, electrically conductive external surfaces may be live) Risk for persons in front of the switchgear because of hot and toxic gases PE potential is increased near the short-circuit location, risk for electronic parts Strong magnetic fields Influence on auxiliary circuits and electronic signals Risk of arc faults and destruction of the switchgear Failure or destruction of the switching devices caused by overshooting of I cw Page 1

15 Determining the settings for t sd in a system In the event of a short-circuit, a circuit-breaker normally trips with a time of t = 50 ms. The delay time t sd is only required in a system to compensate for the potential non-tripping of an upstream circuit breaker (reserve protection). (example on the following page) Last (downstream) circuit breaker () with Setting for t sd = 0ms First upstream circuit breaker () with Setting for t sd = 100ms 50ms of delay time plus approx. 5ms of typical tripping time or 100ms minimum signal duration Second upstream circuit breaker (2) with Setting for t sd = 150ms or rounded up to the next highest setting 100ms t sd plus 5ms typical tripping time of the first circuit breaker Every additional upstream circuit breaker (1) t sd plus a maximum of 50ms action time of the downstream circuit breaker Settings of the delay time for ground fault tripping analogous under observance of the corresponding delay time Page 15

16 Determining the settings for t sd in a system Example of calculating the grading times For ETU25B ETU27B For ETU 5B to 76B Without With = ON tsd = 00 tsd = 200 => -Q11 => Arc quenching after approx. Arc quenching after approx = 5ms = 25ms 1 = ON tsd = 00 tsd = 150 => -Q21 => Arc quenching after approx. Arc quenching after approx = 5ms = 185ms 2 = ON tsd = 200 tsd = 100 => -Q1 => Arc quenching after approx. Arc quenching after approx = 25ms = 15ms = ON tsd = 100 tsd = 0 => -Q1 this makes tzsi = 50 ms = active Arc quenching after approx. => = 15ms Arc quenching after approx = 85ms tsd = 0 tsd = 0 => -Q51 => Arc quenching after approx. Arc quenching after approx = 5ms = 5ms 5 The delay times which need to be set are reduced thanks to! Page 16

17 Technical conditions Technical requirements for the line: twisted in pairs; at least 0.75mm²; maximum length: 00m recommended type LSYCY 2 x 0.75mm² Line lengths of more than 00m are possible; this depends on the cable cross-section and the protection against negative influences such as electromagnetic or transient faults A " IN" cannot be connected to more than 20 " OUT" (downstream); no more than 20 downstream circuit breakers connected in parallel A " OUT" cannot be connected to more than 8 " IN" (upstream); no more than 8 upstream circuit breakers connected in parallel The WL module must always be the first CubicleBus module to be connected to the COM15 or the terminal strip X8 (Cubicle Bus) of the WL Page 17

18 Withdrawal of the signal OUT in the event of a short-circuit after clearance of the short-circuit current, at the earliest after 100 ms, however OUT in the event of a ground fault after clearance of the short-circuit current, at the earliest after 100 ms, however MV OUT to the medium voltage after clearance of the short-circuit current, at the earliest after 500 ms, however The OUT signal is withdrawn after s at the latest Page 18

19 Example network without coupling switch SENTRON WL module 5 6 SENTRON WL module 5 6 SENTRON WL module 5 6 SENTRON WL SENTRON WL module 5 6 module 5 6 SENTRON VL SENTRON VL COM2x 5 6 Page 19

20 Example network with coupling switch without outgoing circuit breaker SENTRON WL module module SENTRON WL module 5 6 SENTRON WL Page 20

21 Example network with coupling switch and outgoing circuit breaker SENTRON WL module module SENTRON WL module 5 6 SENTRON WL SENTRON WL SENTRON WL module 5 6 module 5 6 Page 21

22 Example network with coupling switch and outgoing circuit breaker 1 t sd = 00 2 t sd = 00 Coupling switches are a grading level of their own t sd = t sd = 100 t sd = 0 The connection for the COM10 is different. Page 22

23 Example network with medium voltage Page 2 Blocking signal to medium voltage.

24 module WL Function via rotary coding switch OFF S G S+G Test module deactivated module only effective for short-time delayed short-circuit protection module only effective for ground fault protection module effective for short-time delayed short-circuit and ground fault protection Test position for checking functionality TIE BRKR Connection terminals for tie breaker IN Input for (blocking) signal -> this circuit breaker receives signal OUT Output for (blocking) signal -> this circuit breaker sends signal MV OUT Output for (blocking) signal for reporting to the medium voltage (floating contact; 50mA at 150 V AC/DC). Minimum signal duration 500ms Page 2

25 Test position Test position on rotary coding switch: signal is permanently sent to the upstream circuit breaker Module additionally sends a signal to the connected WL. In this way, a communication connection can be tested. (As if the blocking signal were coming from the downstream circuit breaker) The "Test of the S settings" function allows a potential "feeling" for the set time t sd. For t sd = 0, t = 50 ms applies Test button on module: Temporary testing of the signal displays and outputs on the module itself. Identical to all CubicleBus modules Page 25

26 TIE BRKR Modul SENTRON WL The TIE BRKR function (1, 2) ensure that even when the tie breaker is off, the IN signal (, ) directly transferred to the output OUT (5, 6). Without the TIE BRKR function the signal would not be forwarded Page 26

27 VL function or VL ETU with rotary knob: Short-circuit: Standard setting for the short-circuit protection function is = OFF. The function must be activated via communication. Ground fault: standard setting for the ground fault protection function is = OFF. The function must be activated via communication. VL ETU with LCD: plus Short-circuit: Standard setting is = OFF The short-circuit protection function can be activated via the menu in the display or via communication. Ground fault: Standard setting is = OFF The ground fault protection function can be activated via the menu in the display or via communication. Page 27

28 Required components, WL Short-circuit Ground fault For ETU5B Local parameterization WL CubicleBus module WL9111-0AT5-0AA0 ETU5B + + For ETU76B Local or remote parameterization WL9111-0AT56-0AA0 WL9111-0AT21-0AA0 ETU76B Page 28 Current converter 1200 A / 1 A

29 Required components, VL Short-circuit Ground fault VL COM20/21 ETU10* ETU10M* ETU20* ETU0M* + + VL9000-8AU00 VL9000-8AV00 ETU12* ETU22* * With communication function Page 29

30 for WL, VL, WN6 and WN1 WL / VL functionally identical WN6 Functionally identical to WL / VL Connection points can be found in the manuals of the respective circuit breakers For the technical data of the system, the weakest part is decisive in each case e.g.: WN6 upstream=> not more than parallel WN6 instead of 8 parallel WL WL VL WN6 Page 0

31 Example: function in the event of a short-circuit A) B) t sd = 00 ms OUT IN t sd = 00 ms OUT IN t sd = 200 ms OUT IN t = 50 ms OUT t = 50 ms OUT Page 1

32 Example: function in the event of a ground fault A) B) t g = 500 ms OUT IN t g = 500 ms OUT IN t g = 00 ms OUT IN t = 100 ms OUT t = 100 ms OUT Page 2

33 Example: function in the event of a short-circuit t sd = 00 ms OUT IN 1 With and without function in grading level t sd = ms Trip OUT 2 t sd = 0 ms t sd = 100 ms Trip t sd = 100 ms Page

34 List of abbreviations ETU G I I cw I i I n N MV Q S t d t t sd Electronic Trip Unit Ground fault protection Instantaneous trip unit, instantaneous short-circuit tripping Rated short-time withstand current Instantaneous short-circuit current Nominal current Neutral conductor Medium voltage Circuit breaker Short-time delayed short-circuit protection Delay time time = 50 ms (delay time) Delay time of the short-time delayed short-circuit protection Zone Selective Interlocking short-circuit identified and set OUTsignal active ( time = 50 ms) Page

35 Thank you for your attention! Rainer Huentemeier Productmanager IC LMV LV GP ACB&F V Huentemeier / Pikulicki