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Entry type: FAQ Entry ID: 109740461, Entry date: 07/10/2017

Technical information for 5SM6 AFD unit

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1. How to find technical information

Technical information (technical specifications, dimension drawings and more) on the AFD unit can be found in the Siemens Industry Online Support:

2. How to find specification texts

Specification texts are available at the following link: http://www.siemens.de/ausschreibungstexte.siemens.com/tiplv/index.html#2/TN_2427

3. Is it possible to use the 5SM6 AFD unit, 1+N with multi phase circuits?

No, the AFD unit is only designed for branch circuits with an alternating voltage of 230 V.

4. Ca add-on units (miniature circuit breaker/MCBs, RCBOs) of other manufacturers be added?

No, only the specified Siemens products may be added, as the add-on device is triggered by means of an internal connection.

5. Which device combinations are possible?

The modular block design allows more than 200 different combinations to be implemented simply and fast (various rated currents, characteristics, rated fault currents, switching capacities, etc).
All miniature circuit breakers (MCBs) 1 + N can be installed on the 5SM601* AFD unit in 1 MW (5SY60*).
The following miniature circuit breakers and RCBOs 1 + N can be installed on the 5SM602* AFD unit in 2 MWs: 5SY4*, 5SY6*, 5SY7*, 5SL4, 5SU1.5*

6. The AFD unit switches off at an overvoltage of 275 V. Does this also replace a surge arrester?

No, the AFD unit doesn't meet the requirements for a surge arrester in accordance with DIN EN61643-11. The disconnection at >275 V is only a protection for the internal solid-state components. The integrated overvoltage protection refers only to the "normal" overvoltages from neutral point displacemen (up to 400 V).

7. Why is it generally not possible to get the AFD unit to trigger with self-tests?

Self-tests generate instable, sporadic arcs. In other words, an arc that can only occurs over short distances between electrodes. Such arcs are very unstable. They last only very briefly and the position of the conductor has to be adjusted always. Furthermore, there is generally no acutal combustible material in the contact with the arc and an ingnition is very unlikely (often even impossible, cf. salt-water solution). Even though such arcs are detected by the AFD unit, there is no triggering, because these events do not yet represent any danger. The 5SM6 AFD unit detects stable arcing fualts that burn long and steady. It is almost impossible to produce such arcs by hand. Product standard IEC 62606 contains suitable  test conditions for this and these are described there. A stable arcing fault is ignited here with a defect insulation material and the device is forced to trigger. Carbonized cables/wiring and electrodes are used.

8. What needs to be considered during a dielectric test?

As described in the operating manual, the AFD unit must be disconnected if the insulation measurement with a testing voltage > 250 V. The solid-state components are located in the upper section of the AFD unit (output side). When conductors are connected, this high test voltage therefore comes into contact with the solid-state components and these are damaged.

If the test voltage < 275 V, nothing happens. Because the power supply unit is drawing a current, however, it acts like an insulation fault.

9. Does a function test have to be carried out on the AFD unit in acc. with DIN VDE 0105-100 (proof test for electrical installations)?

The product standard stipulates self-monitoring for arc fault detection devices. The Siemens AFD unit carries out an internal self test twice daily. With the 5SM6*-2 AFD unit, a manual test can also be triggered with a test button. DKE/UK 964.1 is currently drawing up, together with the wiring regulations authority, appropriate requirements for the later integration in the DIN VDE 0100-600 and DIN VDE 0105-100.

10. How can I protect a triple-phase circuit?

Siemens currently has no such protection equipment. The use of AFD units to protect triple-phase alternating voltage systems (three-phase current circuits) is not required according to the standards. However, such a protection device will be available in the medium-term.

11. How should the transition period in the DIN VDE 0100-420 be handled?

The standard DIN VDE 0100-420 (VDE 0100-420):2016-02 is valid for the expansion and upgrading of existing systems. The previous edition DIN VDE 0100-420 (VDE 0100-420):2013-02 has been withdrawn upon the issue of the new edition. However, the previous edition remains in force until 18/12/2017 due to the defined transition period. As a result, electrical installations that were installed up until 18/12/2017 can draw on both standards. From 19/12/2017 forward, the standard DIN VDE 0100-420 (VDE 0100-420):2016-02 alone is to be used. A plant that is in planning/construction but will not be completed until 18/12/2017, must therefore meet the requirements of the 2ß16-02 edition.
In the case of unchanged existing sytems, with the new edition of DIN VDE 0100-420 no additional arc fault protection needs to be performed in branch circuits with arc fault detection devices (AFDDs).

In the statement issued by DKE on 03/08/2016 it is again pointed out that the previous standard from 2013 has been withdrawn. Tip for the transition period. The only purpose of the transition period is to allow already commenced projects to be continued and completed without any problems or complications. However, no new planning should be based on the standard that has been withdrawn. In the event that a loss would be incurred at a later date, the electrician who performed the work would be held liable. The question of why the planning was executed based on a withdrawn standard would be posed. It is not advisable to take on this responsibility.

12. Does the AFD unit have to be retrofitted in existing systems?

No, the AFD unit does not have to be retrofitted in existing systems. However, the operator should be notified about the new DIN VDE standard. The obligation to retrofit in the event of changes of purpose and upgrades or extensions to an existing system remains unaffected by this (see point 11).

13. How long is the warranty period of the AFD unit?

As with all Siemens products, the warranty period of the AFD unit is two years.

14. What is the expected service life of the AFD unit?

The 5SM6 AFD unit has an FIT rate of 180 - a purely statistical value for the failure probability of the individual components. From a statistical perspective, this means 180 failures in one billion hours. However, there are other effects that could limit the service life, such as material migration, diffusion, evaporation of liquids in some capacitors, mechanical/thermal stress etc. The components that generally fail first are the capacitors. As a consequence, these were selected so that they have an MTTF of at least 30 years at rated load.

15. Do insurances reduce premiums when AFD units are installed?

No information is currently available on this topic. The AFD unit is currently described in detail in section 3.4 of the publication of the German "Versicherer zur Schadenverhütung" (VdS 2349-1:2015-03(01)).

  Brandschutzschalter_FAQ_2017_07_06_EN.pdf (87,6 KB)

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