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Hi all, does anybody know if there is a scada monitored interlocking system available on the market that can replace the mechanical kirk key interlock? Thanks!

A Y/YG transformer, Y side connects to a source and Y grounded side connects to lines. There is no zero sequence current return path as the Y side is ungrounded. However, for a core type transformer the residual leakage flux through the tank wall cannot be ignored. The air gaps have very high...

Can someone tell me whether a POTS splitter can increase the internet speed? Thanks

HI all, Can someone share your practice of dealing with abandoned underground feeder cables from substation to raiser poles on street, which the cable cannot be pulled out due to the ruptured ducts. Thanks

What standards that manufacturers should comply when doing their protective relay type tests or product tests before release the products? Thanks

Is an inverter based solar generation a true grounded 4-wire wye system that allow zero sequence current flow?

How does it affect the system by adding a grounding transformer to a 4-wire ground wye system? Please see the attached sketch. Thanks!

UR T60 differential mis-operated on an external downstream fault. I looked into the relay settings and found several things I thought may cause the T60 mis-operated from most likely to least likely in the following order: 1) SRC 1 doesn't get any frequency and phasor measurement 2) in...

Some modern relays have a "Reset Time" for ANSI or IEEE and IEC inverse-time overcurrent curves. I understand the reset time is to emulate the disk type relays for the disk to return its zero position. My question is how does the reset time in the modern relays affect the TCC curves so as to...

Does anybody know any requirement on placing the fire extinguishers in a transformer station, where and how many? Thanks!

Hi all 3P short-circuit MVA is very clear, pre-fault_VLL*If*1.732. But how do you guys see the definitions of SSC MVA for LG and LLG faults?

Hi all Any ideas about sizing a cable for DC? Thanks

Hi All Does anybody see any problems on this temporary operation: We are replacing 2 transformers on a single DESN station. Two existing 110kV/14.2kV 20MVA transformers will be replaced by two 30MVA transformers. First one is going to happen in spring and the second one is to happen in fall...

May I ask someone correct me if I am wrong here. Assume the remanent flux on a CT core is 80% of the pu value, therefore, can I say: 1) there is only 20% capacity left before it saturates 2) the secondary current will be reduced by 80% Thanks a bunch!

Hello, does anybody know if there is a requirement in North America that sets the voltage unbalance limit for a utility supply? Thanks in advance!

Does the instantaneous current value of the 2nd harmonic from all 3 phases cancel each other on the neutral during a transformer inrush? The question was raised from setting up a neutral or ground element, do you need to avoid the inrush? Any differences between Wye primary and Delta primary...

Are wind turbines induction generators? Is there a gear box that is used to adjust the rotor speed according to the wind speed? What mechanism is used to prevent it becoming a big motor? Thx!

A CT nameplate is labeled as such: 1200/800/600-5 X1-X4: 1200-5, 2.5L800 X1-X3: 800-5, 2.5L400 X2-X3: 600-5, 5L400 It seems the CT has three ratios on the given tap connections. However, if connect the taps as below you may get: X3-X4: 400-5 X1-X2: 200-5 The questions are: 1) is this a common...

Assume there is a resistive and inductive line, which means no capacitance considered. A 3phase short circuit occurred on the end of line, let's also assume the source is 1pu with 0 phase angle. My question is will it be possible that at some point along the line the voltage leads the source...

Can someone give typical realistic SCMVA levels on 230kV station bus and 115kV station bus of transmission networks from experience?