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In the specs, it is mentioned that the max overvoltage factor due to any switching will not exceed 2.3 p.u . What I understand is that the peak TRV that appears as soon as the arc is extinguished should not be more than 2.3 times the peak value of the phase voltage corresponding to 145 kV...

Could not understand one target condition in the attached doc: De-energizing shunt reactors ---opening operation ---target is "medium arcing time".. Is this another way of saying that it will open after the initial dc offset is finished (i.e. 1.5 secs approx.) ? Thanks friends !! The solutions...

Dear friends, I need in urgent info. The factor of 2.3 p.u stated as "the overvoltage factor during any of the above switching duties" as per IEC is under question. The manufacturer has type test reports to prove that the 132 kV rated CB can break a capacitive current of 656 A r.m.s with a...

Thanks QBplanner and FPelec, The island has existing load (oil wells and refineries) supplied by local generation. The project is past engineering phase and is under manufacturing phase. CB manufacturer has confirmed that they have type test reports to prove the CB has breaking capacity upto...

QBplanner : Client wants pf at 0.9 to 0.95. So 120 MVar of cable to be compensated with 2 reactors 60 MVar each with variable taps ranging from 30 MVar to 60 MVar. Source end will compensate for p.f. Load end will be reduced and finally switched off in heavy load condition to reduce the current...

Thanks bacon4life, Sorry for the details spread over different threads. Will take care.

Can the AC circuit breaker 40 kA (47.6 kA assymetrical) 50 HZ 145 kV rated to break 315A reactor current, break the attached waveform ? I understand ,the r.ms value of the wave comes to around 614 A.. Current zeroes are there but at the lower end of the waveform !! How will it effect the CB? Any...

Thanks Fpelec, So what is the CB spec that I should check to find out whether it can interrupt this 500 A during 1.5 sec ? The scenario is like this: A submarine cable (120 MVAr,100 km) compensated by 2 shunt reactors 60 MVAr each with variable taps . System voltage is 132 kV. I got the CB...

Thanks Fpelec and warross . It is nice to get the opinion of industry experts [smile]!!

Hi friends, My EHV CB (rated 145 kV) is rated for breaking capacity 40 kA. But the reactor breaking current is only 315 A. Also, the Cable charging current breaking capacity is 160A only. However, the Back to Back Capacitor Switching current breaking capacity is 400A. Why the current values...

Is it possible to use Pre-insertion resistors in a 132 kV GIS CB. The switching duty is for energizing a shunt reactor supplying a 100 km long 132 kV cable. The studies indicate a huge DC offset without current zeroes for approx 1.5 sec. Inserting a resistance can decay the DC component faster...

245 kV is the rated power frequency withstand value. The rated voltage is only 145 kV. So the CB can break an rms value of only 315 A for reactor switching. Quite a remarkable thing when we compare, it can break 40 kA under fault conditions but a switching duty involving a reactor is only 315...

I will check about the significance of the min value of 41 A given by our supplier. What is the limiting value ? Sorry couldn't get that. Is it that the CB could break the current without the current zeroes if it was only 315 A ( Again question comes to mind whether this 315 A is rm.s or peak ?)

Also, the above current value is 500 A (peak value around 1000 A) and there is no current zero appearing for 1.5 sec !!

Thanks waross, You got my problem right. The spec mentions 40 kA asymmetrical breaking capacity. Also , most of the sub-transient , transient waveform show current zeroes in the text books. But the problem here is that the switching study waveform displays an asymmetrical waveform with "no...

Sorry , I forgot to mention that it is an HVAC CB. 50 Hz. employed in a 132 kV Transmission system.

Hi friends, I have a 275 kV SF6 CB having the following rating : Rated short time withstand : 40 kA Rated peak withstand : 100 kA Rated making current : 100 kAp Rated breaking current asymmetrical : 40 kA Out of phase breaking current: 10 kA First pole to clear factor : 1.5...