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iC60 Energy let through and tripping times

Archives: Power Distribution

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Adam_Harding
Crewman
Crewman
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iC60 Energy let through and tripping times

Hello, 

 

I have a question that relates to this FAQ on the Schneider website: 

https://www.se.com/th/en/faqs/FA346069/

 

It states:

"- tripping of short-circuit protection (magnetic tripping device): if the current exceeds the threshold of this protection device, the breaking time is less than 10 milliseconds

For short-circuit currents exceeding 20 times the rated current, the time-current curves do not give a sufficiently precise representation. The breaking of high short circuit currents is characterized by the current limiting curves, in peak current and in

energy. The total breaking time can be estimated at 5 times the value of the ratio (I2t)/(Î)2. Verification of the discrimination between two circuit breakers"

 

What is the reason for estimating the total breaking time with a 5x multiplier of the ration between (I2t)/(Î)2

 

Does (Î) = the limited peak current (assuming current limiting of upstream protective devices) or is this meant to be peak current?

 

Is it possible to calculate that the first half cycle rise in current, will cause the MCB to trip by pushing the circuit breaker to a point of no return in respect to the opening of contacts (where it will not reclose). 

 

Thanks, 

Adam Harding

Arup  - Hong Kong

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Accepted Solutions
J_Travostino
Admiral Admiral
Admiral

Re: iC60 Energy let through and tripping times

Hello @Adam_Harding and @AlexandreBoulet 

 

Here is a brief answer to your question:

 

The ratio I²t/(î)² is calculated with the area of I² per the time and the I peak is limited by the circuit breaker.

At 20 times of magnetic threshold the time of current is lower than 10 ms.

Depending on the shape of the current wave, at a given peak, the wave duration (Δt) and wave I²t relationship is as follows for a ½ sine wave or the consequence of a limitation

 

Depending also the circuit breaker (his own limitation) and the time of the breaking, the waveform could be different (triangle) but by taking into account a factor of 5 we take the worst case.

 

If you need further information please contact the Customer Care Center of your region following the link below:

 

https://www.se.com/ww/en/work/support/country-selector/contact-us.jsp

 

 

Staying at your disposal

 

BR

Julien Travostino
Power Distribution & Digital forum community owner
Power Products Div.

See Answer In Context

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2 Replies 2
AlexandreBoulet
Administrator Administrator
Administrator
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95

Re: iC60 Energy let through and tripping times

@J_Travostino can you help or should Adam contact the local CCC for this question? Thanks in advance.

Alexandre Boulet
Schneider Electric - Exchange Launch Leader
Tags (1)
J_Travostino
Admiral Admiral
Admiral

Re: iC60 Energy let through and tripping times

Hello @Adam_Harding and @AlexandreBoulet 

 

Here is a brief answer to your question:

 

The ratio I²t/(î)² is calculated with the area of I² per the time and the I peak is limited by the circuit breaker.

At 20 times of magnetic threshold the time of current is lower than 10 ms.

Depending on the shape of the current wave, at a given peak, the wave duration (Δt) and wave I²t relationship is as follows for a ½ sine wave or the consequence of a limitation

 

Depending also the circuit breaker (his own limitation) and the time of the breaking, the waveform could be different (triangle) but by taking into account a factor of 5 we take the worst case.

 

If you need further information please contact the Customer Care Center of your region following the link below:

 

https://www.se.com/ww/en/work/support/country-selector/contact-us.jsp

 

 

Staying at your disposal

 

BR

Julien Travostino
Power Distribution & Digital forum community owner
Power Products Div.
Tags (1)