Insulator: Learn the Purpose, Cost, and Lead Time to Procure

Cap bank fixes the poor power factor only. It does provide a low impedance path for harmonics but it is not tuned to filter them out. A regulator does not remove the harmonics and neither does it fix the power factor. A filter bank addresses both - it is made up of inductors and capacitors therefore tunable and also capable of releasing VARs. (Note: one manifestation of harmonics is voltage flicker). Learn more.

All methods mentioned help with limiting the fault current. The cheapest though is a neutral inductor, especially when mounted directly on the transformer. Learn more.

Current limiting fuses directly on the transformer secondary are rare. Mostly because of the continuous current requirement (1000amps or more) - fuses are rarely fabricated this large. This was a trap answer.

A synchronization check is done using a relay. It needs low voltage input (from both sides), obtained using a voltage transformer a.k.a. instrument transformer. Learn more.

Surge arresters are specified to discharge lightning strikes and switching surges. The equipment/system insulation can handle temporary overvoltage. Learn more.

Transforms voltage and current only. Power remains the same on both sides. Learn more.

You need a device that allows a certain frequency to pass (CCVT and line tuner) and a device that stops it (wavetrap). Note a capacitor voltage transformer does not come with coupling accessories as such it does not work for transmitting carrier frequencies.

Click here for more detail on wavetrap and here for CCVT.

Both the breaker and the switcher have an interrupting chamber that can safely interrupt the fault current. A switch does not. A switch will draw an arc, that is damaging and a safety hazard. Learn more about switches here and circuit switchers here.