Uses a bolted 3 phase short circuit and claims to quench the arc in less than 2ms!!

http://www.moeller.net/en/products_solutions/power_distribution/power_communication/arc_fault_protection/index.jsp

Any thoughts??

2mS is pretty fast, I would like to see some actual test results. However, this concept seems to work, GE is already doing the same thing. Simple concept, most current takes the path of least resistance, so they create a lower resistance path and therefore the arc extinguishes.

P.S. Great video to see for the ongoing doors open/closed debate.

I can see the light sensors detecting an arc this fast, but if operation is monitored by current sensing, the 2 ms sounds too fast. What kind of algorithm can calculate the current from sampled data in less than 12% of one cycle? And then there has to be some processing time and some time for operation of the arc quenching device.

The Moeller device creates a bolted fault, while the GE device apparently inserts impedance to keep the system from having to withstand full bolted fault current.

"...the arc fault is quenched in less than 2 ms after initiation." Sounds like the two ms does not include detection time.

It does seem rather fast! The sales literature claims "The system can detect,
analyse and quench arc faults in only two milli

seconds

See here http://www.moeller.net/binary/anlagentechnik/arcon_ref_cs_en.pdf

I'd never heard of it until my local Eaton sales guy mentioned it, apparently Eaton own Moeller now (Or Klockner Moeller for us older engineers!!

Arc burning time 2ms/5ms



It does include the arc detection time. Optical detection is very fast, and the overcurrent can be detected by analog information.

Arc burning times of 2ms (LV) and 5ms (MV) can be reached.

I believe we have talked about this on another part of this forum that you may use the search function to find the information.

An authority from GE, whom is involved in the GE based arc fault containment dome extinguisher, and made comments on the forum to help understand this concept.

Maybe someone can find the link and post or if not search for (GE) and you can find that posting. The method is somewhat amazing how another arc can draw the original fault into a containment dome.

Thanks

Sorry, I should have looked at the link first. The device uses a little different approach to reduce the IE then GE utlilizes.

What analog method can be used to detect overcurrent and unblock in less than 2 ms?

Comparator.

What are you comparing the current to? The idea is to operate the device if the current exceeds load current. In about 1/8 of a cycle from the start of the arc, you have to determine if the current is greater than some set value and either allow or prevent the device from operating, and still leave enough time to actually operate the device.

I don't think the manufacturers reveal all their secrets. I have seen some test results, and I am happy with that.

I got a link to a video on the Arcon system from my sales guy



http://www1.eatonelectrical.com/ElectricalEMEA/movie.html

still claims 2ms time to detect and extinguish an arc!

To see is to believe

I was present when arc quenching was demonstrated (equipment by Eaton/Moeller & Vamp). Dual sensing (light & current) was used, and the arc was quenched in less than 2ms! I saw the test, I saw the recordings - very convincing for me.

I believe that this system has been developed by http://www.vamp.fi. It looks a lot like VAMP's 221.

JASE

This is a fiber optical sensing relay, and the 2 ms is the response of the relay? For arc flash hazard assessments the cirucuit breaker opening times should be added. Misleading marketing...?

I have installed four arc detection + quenchign system, so can speak with some experience.

In the USA, I see GE have some recent developments in arc killing/quenching. I don't understand the technology and it seem GE do not reveal too much and have some clever IP concealed.

In terms of Moeller & VAMP these concepts (i.e. detection and quenching) have been used in (and exported from) Europe now for over 10-years and are out in the public domain.

The VAMP detection system electronics votes on current and light events within 2ms. This is a known & published fact and Vamp could confirm this for any non-believers out their.

To achieve IEC-60255 compliance for protection relays, the relay trip outputs must be a relay contact and have a large AC/DC rating. The fastest acting relay that meets the IEC spec takes approx 5ms to close once activate. This is why you have 2ms + 5ms = 7ms. In detection-only arc protection systems, then the CB must clear (i.e. approx 35-120ms).

However - where a quenching unit is used, such as the Moeller/Eaton unit, the activation signal is via electronics (i.e. transistor) and responses are uS not mS. The quenching unit is also lightning fast in uS to apply the short circuit. In this was, the activation time is ~2mS.

Once the quencher has fired, a conventional contact also clears the upstream circuit breaker - as the quenching unit is time-limited (i.e. 1sec rating).

Hope this helps.

Thanks. I have several questions though...

1. Is it necessary for low voltage switchgear to have so short arc clearing? The holes in the switchboard in the video looks real, but according to information from IEEE it would take 0,25 seconds for these holes to appear, not 1,4 ms...

2. What is the respons time of the current sensor? I think the risk of false alarms is high, and when the false alarm fires the pyrotechnics the cost of such a false alarm is high.

3. As the upstream circuit breaker need to be opened, the fault is not cleared before the breaker clears, 40ms at best. Therefore this is misleading advertisement.


Also, this is a relatively large unit that cannot be retrofitted.

I have just tested a prototype LV arc eliminator and the total time was 4ms.
a little less than 2 ms for the electronic part.



It is important from personell safety point (PPE criteria) of view that the arcs are quenched as early as possible during the increasing pressure that use to reach its peak in approx 10 ms. After 4 ms there is still a low pressure very limited toxid gases and limited heat. The dangerous phase is over and the upstream CB can take care of the short circuit.
After this it is still clean and you can start again as soon as the reason for the flash over is eliminated. My prototype can be resetted and is then ready again.
But it is still a prototype and it will take some time before it is available.
We also wait for the new UL 2748 Safety for Arcing fault Mitigation Equipment (LV.)