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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 ?

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) ...

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...

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?

Hello experts I was reading about anti-pumping device. So basically, (if i understood correctly), this device protects tripping mechanism of the circuit breaker from having too many CLOSE-OPEN loop commands, which could happen when the CLOSE command is given, when fault is not cleared. Then...

Hello experts, In my project, i have a requirement like this : "remote trip signal shall be wired directly to circuit breaker trip coil". Could somebody confirm my understanding: If i am not mistaken there are two types of wiring a trip signal: 1) Trip signal wired to IED or Relay 2) Trip...

Hello Experts, Could somebody explain me what are the differences between : RELAY vs. BAY CONTROL UNIT vs. DIGITAL TRIP UNIT vs. IED ? What i think is : RELAY = very generic naming, if it is used for CONTROL, we can call "control relays" as BAY CONTROL UNITs. DIGITAL TRIP UNITS are mostly...