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What you mean by "magnetic flux outside the iron core"? I have used term "DC offset" instead of "zero offset", both are same.

It is due to saturation of magnetic core. In steady state, Flux produced in one half cycle is cancelled out by MMF of next half cycle. During charging, we need to close CB at exact point on wave (taking residual magnetism in account) to acheive normal current levels without any inrush...

In this case THD is 2.7% and difference in neutral current is >50%. There should be some other issue.

Neutral current should be = Vector sum of currents in all three phases. So, you need phasor angless.

From this, CT polarity is the probable cause of trip. Checking CT polarity and correcting is the solution. Further, regarding single point earthing for CT secondary circuit: Generally, one side set of three phase CTs make has siingle point earthing. And other side set of three phase CTs has...

Practically, I have seen one CT failure due to CT open circuit in metering core at 132kV level. In all other cases, there was another current path developed by melting of cables / terminal blocks etc.

violent failure of CT with explosion: It depends, if it is dead tank type CT with oil filled and porcelain housing, pressure developed can explode CT. In some cases over voltage can create insulation failure of cables, or terminal blocks, causing short circuit of CT secondary. In this case CT is...

DC earth fault locator kits (based on low frequency injection) are avaiable, which does not require isolation to some extent. But it needs expert person to identify exact location.

"bay controller unit" is an IED used for control and monitoring. It has all the functions of LCC and can be operated from Local or remote SCADA.

Are you talking about three positions: [ol 1] Disconnector close, Earth switch open Disconnector open, Earth switch open Disconnector open, Earth switch close [/ol] It has advantage of having only one drive mechanism for both disconnector and earth switch.

Temperature is missing in this rating. 105AH will at a particular temperature (Normally 27 deg C).

Does low inrush current is oberved always in C-phase, or it is changing randomly with every attempt? Is there any controlled switching device?

CT star point is formed in the yard for EHV and UHV substaion.

IMO, arc cuases melting of conductor. After melting, molten material will go down by gravity.

Once arc is produced, air is no more insulator. It is chain of ionized particles. Elongation of arc will reduce the current but cannot make it Zero. When arc is extiguished at any current Zero, recovery voltage appearing across ionized particles will re-establish arc, because air does not regain...

These days bay controller units are used to synchronise two networks in transmission sector. Not sure about generating ends.

May be... VT secondary circuit wiring issues like double earthing, operation of VT selection relay... DR needs to be analyzed

Its Phase to Phase Under Voltage start. When it will trip, it will show Trip. Application configuration needs to be checked, as trip contact can be operted from start event.

Yes Yes Discoonector can be operated when CB and ES is open, and ES can be operated with disconnector open. Mostly interlock bypass is not required for checking operation. Yes, if interlocked with keys, Keys needs to be moved between ES and disconnector. Bypassing interlocks is also sometimes...

Local earthing should be at the point of working. Even if you use two local earthing, distance between these two should be very low (say <3m). There will not be any circulating current. In one practical case, when working at 11kV line, worker pulled conductor of 11kV line with a jerk. It started...