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Hi SA07, A 2,5 Hz/s setting is a rule of thumb that should work fine for low inertia small units if there enough power imbalance after loss of network inteconnection. You can still estimate the rate of change of frequency from the motion equiation of rotating masses (Newton's second law) based...

Hi cranky108, Thanks for your comments. Yeah, that's right. Recloser control is a microprocesor based unit but not that modern so as to define user logic or at least we have not found how. Regards, Carlos

Hi RRaghunath. Thanks for your feedback. We will check again. Regards, Carlos

Hi RRaghunath and thanks a lot for your reply. Here are the answers to your questions: Is neutral CT of 33kV winding wired to relay? No. In fact neutral CT is not available. Is 33kV neutral solidly earthed? Yes, solidly grounded. What is the characteristic angle chosen for 67N? -45 degrees...

Hello everyone, In a MV distribution network with local gas engine generators we use directional relays due to the meshed topology of the grid. Step up 34,5/ 0,48 kV transformers associated to generators are protected by reclosers on the HV side. These reclosers have two groups of settings...

GE L90s or L30s work with 3 terminal lines. The communication protocol for exchanging 87L data is not IEC 61850 but a propietary one. You should have all the three devices with two communication channels so that each one communicates with the other two simultaneously. In case a link fails...

Hi GroovyGuy, Thanks for your reply. Indeed retrofitting would be the best solution but we are dealing with Oil&Gas industry and managers will not be willing to invest and lose production to improve GF protection. We have to find a solution with what we have in hands. All protection devices do...

Hello Dear Colleagues, I have a 4,16 kV industrial switchgear with high impedance grounding through a ZigZag transformer limiting fault current to 50 A. Unfortunately the MV metalclad switchgear came without zero sequence CTs and some phase CTs have a high ratio 2000/5 limiting both...

Dear Sirs, Could you please explain the meaning of a feature called "DEF plain and Blocking modes" in distance relays? Thanks in advance for your help. Regards, Charlie

Thanks you for posting. I will try to get documentation from customer and let you know

Hi Rasevskii, Thanks for your reply. I think this might not be a 100% stator ground relay as you say based on the following reasons: 1. Third harmonic was not developed until the late 1970s and this relay seems much older. 2. It does not have a setting for third harmonic level and it is well...

Dear Sirs, I am dealing with the replacement of a generator protection system which includes an electomechanical relay type CUH90C from Brown Boveri for detecting stator grounds. The fact is that two voltage signals are wired to the relay namely one from the grounding transformer and one from...

Electrolitic, Thanks for your valuable comment. Could you recommend a manufacturer of these type of sensors?

Hello everybody, Where could I find guidelines for protecting wound rotor induction motors? To the best of my knowledge, protection of this type of equipment is achieved in the same manner as for squirrel cage induction motors. But there are still some concerns regarding rotor winding faults...

Thanks Eleceng01, I've succesfully downloaded, installed TOP and performed the required operation.

I got a comtrade file with two current signals. Is there any way to create a new signal from the difference of these former ones? If so, Could this task be done in excell? Thanks in advance for your help

Hello everybody, i'm an electrical engineer and actually i'm performing dynamic simulations of wind turbines but i have had some difficulties with data avaliability. Particularly those data related to equivalent wind speed time series and equivalent torque coefficient tables. (equivalent...

I found the following expression for the small signal stability limit on the P-Q plane: Q = [0.5*V^2*((1/Xsys)-(1/Xd))^2]^0.5 + 0.5*V^2*((1/Xsys)-(1/Xd)) (1) How can i obtain this expression from those corresponding to delivered active and reactive powers? P = (E*V/Xd)*sin(delta) +...

These topic has already been treated in this forum, try an advanced search.

As stated above you must first calculate values for phasors from sampled data, this can be done using FFT but beware these approach fails for highly distorted waveforms.