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Welcome. IT Systems, Argumentation Aid . IT Systems, Argumentation Aid. All Siemens MCCB and ACB products are tested in accordance with IEC 60947-2, Appendix H. For all 500V and 690V IT system applications there are solutions with our products.

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Welcome

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  1. Welcome IT Systems, Argumentation Aid

  2. IT Systems, Argumentation Aid • All Siemens MCCB and ACB products are tested in accordance with IEC 60947-2, Appendix H.For all 500V and 690V IT system applications there are solutions with our products. • The IIT value in IT systems must not be confused with the ICU or ICS values. In all systems, the ICU and ICS values are calculated in the same way. • The IIT value in an IT system is very low as a rule because the impedance of the ground loop is high. The IIT value cannot be calculated because it depends on numerous factors (e.g. weather, soil conditions, contact resistance of the ground faults, etc.).Instead a test method is defined in IEC 60947-2, Appendix H for determining suitability in IT systems at the corresponding rated voltage.=> There is no sense in discussing kA values. Given the current standards and inability to calculate the value, this would not produce any results which could help in configuring the circuit breakers. • The probability of a double ground fault is minimized by the use of a monitoring relay and the direct elimination of the first ground fault. As a rule it is very much in the customer's own interest to eliminate every ground fault as quickly as possible in order to maximize the availability of the IT system.

  3. 1 2 3 Explanation of Short Circuits / Double Ground Faults in IT systems IT system 690V / AC Fault 1 and 2simultaneously -> Double ground fault on the load and infeed sideSingle-pole short circuit, the full interlinked voltage of 690V is at the main contact L1 ! Selection of the circuit breaker by suitability in accordance with IEC 60947-2, Appendix H=> No calculation of the IIT value is necessary or possible Fault 3 2 or 3-pole short circuit Multi-pole short circuit, a voltage of 690V/1.73= 400V is at the main contacts! Configuration of the circuit breaker using the Icu and Ics values. L1 Trans-former ungrounded L2 L3 690V 400V ICS Impedance Ground loop IIT

  4. Thank you Title of the presentation IC LMV LP PO P2 Stefan Häbel

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