Recent content by Murlinor

Thanks! That was really informative.

Thanks sir for your reply. The manufacturer is offering a 38kV switchgear and saying that this switchgear can be used in class 1, div 2 area based on the following standard: NEC 501.115(B)(1) it states: (1) Type Required. Circuit breakers, motor controllers, and switches intended to interrupt...

Friends, I want to install a switchgear in a class 1 division 2 AEX area. Someone has suggested to use a SF6 insulated padmounted switchgear. The question is if the switchgear tank is intended for use in class 1 division 2 (group D) area, what then about the elbow cable connector to be to...

Thanks for the reply, friends. The client has chosen this system. It confuses me too. Supply network feed->CB->VSD->transformer->Disconnector/earthing switch->cable->motor I have heard that the VSD should not be used as a protection of the cable, so how will this protection scheme be? Could...

Thanks for the reply. So it should be as follows: Supply network feed->CB->VSD->transformer->Disconnector/earthing switch->cable->motor?

Hi all. If one has the following scenarion: Supply network->VSD->transformer->cable->motor. Is it possible to utilise the VSD as a protection against short circuits? Or should one have the following solution: Supply network->VSD->transformer->Circuit breaker->cable->motor Help is appreciated.

Hello friends. I have a 6.6 kV VSD connected to a 6.6/50 kV transformer. I am designing a 50 kV switchgear panel and was wondering if the VSD will contribute to the short circuit current at the 50 kV busbar? Thanks

Hello friend. That means short circuit calculations for subsea installations, one should use IEC60909. Since IEC61363 only covers electrical Installations of Ships and Mobile and Fixed offshore Units. Please advice BR

Hello. I am working with short circuit calculations on subsea electrical installations. Which standard IEC shall be applied IEC60909 or IEC 61363-1? Thank you. Best Regards Murli

Thanx, nice to know that I have understood the standard. Thanks for the help, appreciate it. Best Regards

Thanks for the reply. Formula 12b can be used as an alternative. I have to disagree with you 7anoter4. Assume cmax=1,1, then Kt will be <1 when Xt is higher than aprox. 7.5% or Kt = 0,95*cmax/(1+0,6*xT), Kt-->0 when xT--> Infinite (I think this is the reason why IEC writes cmax, to make sure...

Thanx for answering. I'm sorry for not being clear of what I was asking for. My apologies. In IEC60909, when you calculate the impedance for transformers Zt a impedance correction factor is to be introduced: Kt = 0,95*cmax/(1+0,6*xT), formula 12a in IEC60909-0. This factor is then multiplied...

Hello Friends. For two winding transformers IEC60909 describes correction faactor for impedance. The c factor to be used is cmax. When calculating minimum currents, should the correction factors be omitted? Because the formula for correction factor is based on cmax and not cmin?

Hello Friends. I have a question regarding IEC60909 and bolted fault. Generally for a single phase to earth fault the current can be written as follows: I''k1 = sqrt(3)*Un/(z1+z2+z0+3Zn+3Zf) Where Zn is the impedance connected to neutral and Zf is the fault impedance. IEC omits the fault...

Thanks people. I drew a three phase diagram and saw that the load will be connected in delta, so the 100 A will be the current through each load. I had calculated 173 A, but got confused. Thanks everybody. Appreciate it.