Hi All,
I have a question about fault current behaviour in a ZNyn1 (22kV/0.440kV) transformer, which is being used as an earthing and auxiliary transformer.
For a line-to-ground (LG) fault on the LV (yn) side, my calculations show a very low fault current, which seems to align with standard...
Hi All,
There has been an increase in the need for Special Protection schemes as a result of the ever-changing power system. Would anyone be able to share any guidelines on how to scope, design, commission and maintain these schemes. I would appreciate any direction you can provide. Thanks
Hello All,
Just want to get your view on implementation of SOTF scheme on line diff relays?
I tend to think that being a current based protection no special SOTF(overcurrent threshold based, etc.) needs to be implemented on a line diff. relay. Appreciate your views/experience on this?
Hi,
What is your experience with clearing LL faults at the end of rural distribution feeder with low fault current. The problem is with fault level so low, there is no discrimination against load current. Also, what are the concerns with such a low LL fault going undetected? If this fault...
For transmission lines what are the benefits of having AR functionality reside in Bay Control Unit?
I am used to relays(X & Y) doing the AR; however, of late seen some schemes where BCU does this based on the AR initiate/block signal from relay.
25MVA YNyn0d1, source side ungrounded transformer tripped on Instantaneous EF during energisation. The waveform signature revelled inrush, but the question is how did neutral current appear on the supply side when the star point is floating?
Appreciate any thoughts
What will be the impact of having multiple grounding source connected to Substation bus during normal/fault condition. the situation is:
a. 6.6kV generator connected to the bus with its neutral grounded
and
b. 6.6kV LV side of 3 winding transformer connected to the same bus. The LV neutral...
Hi All,
Can someone shed some light on TF diff stability test shorting the HV and LV winding to bypass TF impedance. How is the injected current controlled as I believe there will be theoretically 0 Z.
The reason to go in this path is because of not having enough current with the standard...
Hi There,
I've a query regarding use of tertiary winding for station service.
We have an application where tertiary winding needs to be used for station service. Basically tertiary will feed into a station service transformer. My question is do we need to ground the corner of tertiary delta or...
I'm analysing the following condition and wanted to know your views.
For a radial line feeding into a transformer(Ynd-275/11kV) what will happen to the TF diff relays during the single pole reclose dead time for the line.
Say for a C phase- Gnd fault, during dead time, TF HV will have A phase...
It is well known fact that transient performance of CVT is inferior to inductive VTs, however, for higher voltages, because of cost benefit, CVTs are used. My question is for distance protection application does using CVTs impact on the performance of the protection system?
Hi All,
I have a query regarding Current Limiting reactor. In a 66/11kV substation with two transformers, is there any preference over voltage level the reactor should be placed? what are the factors that govern the placement of reactor? also can the reactor be installed in series with...
Hi,
I have a breaker with following specification
short time rating: 25kA for 1 sec.
I want to work out time for 30kA fault level. Can this sort of approximation be done?
Cheers
Hi,
I'm working on a project to determine a suitable protection for a MV(11kV) metal clad switchgear. Being an old system I was able to track the short circuit rating of the CBs, however no luck with the rating of the busbar and switchgear. I found that people confuse with CB and switchgear and...
