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Hello experts, Could you tell me, what will happen to CT if the secondary is open circuited for 1min and for 1 hour? Theory says it will be saturated. However, can this CT still be used ? or should i replace this CT ?

Thank you for the reply. That means it is a jumper? Could you explain me, how it is physically done? Because in the terminal drawings i cannot see any jumpers.

Dear Experts, Please refer to the attachment. Could somebody explain me, what is shown there ? I am having hard time to visualise the real physical implementation of this connection. Does this connection mean that these two wires are terminated into the same relay pin (termination point) ...

Hello Sir, Thank you for taking time to respond to my question. But i think you've misunderstood my question. I understand the flow of currents during earth fault and the arrangement of NEUTRAL (grounded or isolated). However, what i wanted to know is that : during earth fault usually the...

Hello, My question is general question (irrespective of the neutral system selected). I often see in text books that current hops back though the neutral. And this current is coming from the ground. How is that even possible?

Dear experts, I have very basic question. In fault current studies it often shows that whenever there is a fault, the current is flowing to the ground and it comes back flowing to the neutral. How is that even possible? Is it the same current that flowed to the ground? Can somebody explain me...

Could you elaborate more on your statement? how i can be sure that my relay is compatible ? I am using SIPROTEC 5, could you give more explanation where i can check this information on relay manual ?

Hello Experts, I have very little knowledge about the FO cables. Could you clarify me the following : I have 2 IEDs that will be connected via fiber optics. And i have several signals to transmit through this fiber optic cable, such as : CB OPEN, CB CLOSED, ES OPEN, ES CLOSED. I do not know...

Hello Experts, Could somebody explain what is the advantagr of using three position switch in the GIS? Can't it be done by Circuit breaker + earthing switch? Or why we can't use just two position switch (no middle position) Thanks,

Hello, In the Medium voltage switchgear circuit breaker, i have 2 trip coils (shunt trip coil and undervoltage trip coil). Can I wire, 4 trip signals to them ? Or do i need a master trip relay?

Hello Experts, What is binary input and output in relay ? I often heard about digital input/output, and hardwired input/output. Is digital I/O same as binary I/O. Also what is the difference between hardwired I/O and binary I/O ? Regards,

Dear Experts, Could you share with me your tips and tricks to read schematics of 100+ pages ? With many pages, I often get lost in between. Therefore, I would really appreciate if someone can share some strategies to handle schematics diagram. regard,

Hello Experts, I am reading GIS specification and i have stumbled upon to a following picture. It relates to base frame drawing of the GIS. Could some body tell me, what does this "shadow" mean in the floor plan of the GIS ? Is there any specific meaning to it ? Thanks...

Hello Experts, Could somebody guide me on the following issue : I have a transformer with circuit breakers installed at both upstream and downstream switchgears. Transformer has many protections like, winding temperature trip, oil temperature trip etc... And I have several options for the...

Hello, Could somebody help what are these two symbols in the SLD ? Second question : Why the number 2 is placed upstream current transformers ? Why not downstream ? Regards, https://files.engineering.com/getfile.aspx?folder=6d3b4ae5-3db7-4005-ae1f-77fe043c188e&file=Capture.JPG

Hello experts, We have a requirement in a client spwcification that 33KV GIS incomer has to have metering function. My question is : provided that the relay IED itself has measurement of voltage power etc..., Is there a need of separate metering panel?

Hello Experts, Does anybody know how to calculate the grounding transformer zero sequence impedance ? I would like to order grounding transformer. And the manufacturer asking me Ohm/Phase value, but no Z% value. Here are the details 1ry side : 66kV Neutral Earthing Resistor Fault current ...

Hello Experts, We are specifying Neutral Grounding Resistor for our industrial distribution system. We already know the fault current level, which is 1000 amp for 5 sec. However, I do not know how to specify the permanent current value. Does any body know, how I can find / calculate the...

I heard one of my colleaugue saying that ENGINEERS HATE NORMALLY CLOSED CONTACTS. Is it true? If yes could somebody explain me the reason?

Does it mean that if i have lockout / latching relay in the circuit breaker, the anti-pumping device is not necessary?