The Forcefield Core is aptly named, as it, along with the Forcefield EU Injector, is the core of any forcefield system. Plug your IC2 Cable into the Injector and place your Core directly on top of the Injector in order to begin creating a forcefield.
The Core itself does not project a forcefield. Instead, when a redstone signal is applied, it pulls EU from the Injector and stores it. See Power below for more detail.
Once you have applied a redstone signal and the core is storing power, you must use one of the MFFS Projectors to actually create a forcefield. Create a Blank MFFS Card and right click the Core to open its GUI. Place the Blank card in the "Frequency Card" slot at the bottom of the GUI, and the Core will write a frequency to the Card, turning it into an MFFS Frequency Card. You can right click open space with the Card to see its frequency, but so far, there is no known usage for the frequency itself. See the Blank MFFS Card page for more info on connecting Projectors.
There are several Forcefield Upgrades available, however, the Core Storage upgrade is already applied, as of Tekkit 3.1.2. There also seems to no longer be a limit to the distance between the core and projectors. Tested at +8000 meters and still connected.
The GUI shows the maximum range of connected projectors and how many projectors are connected via MFFS Frequency cards, however, these are currently not working, do not change, and have no effect.
The Core will store up to 10 million power, where 10 power is generated per EU supplied. Therefore, fully charging the core will require one million EU. This can be applied at any rate, even extreme voltages of 2048 EU/t.
Upon activation of a projector 10 power is consumed Per Forcefield block created, and one power per second, per theoretical block regardless of if its generated. Distance from the projector does not matter, only the number of blocks. Camo Upgrades do not cost additional power. Extenders create more blocks, so use more power.
Example: a 3x3 field activates in the air and is immediately switched off. The power drain is 10x(3x3) + the second it was on 1x(3x3) for a total of 99 power used in that toggle. If the field was left on, it would drain 9power each second. Which is less than 1 EU per tick!
A 3x3 field activates on the ground, 4 dirt blocks are in the field and these field blocks are not generated. If immediately switched off the power drain would be 10x [(3x3)-4] = 50 for activation and the full 1x(3x3) for the second it was on. For a total of 59 power. Each second would still drain 9 power, despite there being dirt blocks in the field. If these blocks are removed with the field active, the newly created spaces would be filled by a forcefield block for 10 power each.
Forcefields are incredibly useful as Shields from Blasts. When a blast hits a Field, it absorbs all of the damage hitting it, at the cost of power. (i.e.Standard TNT exploding against a 1 block forcefield drains 1250 power but prevents any damage to everything behind it) Although a 1 block field won't shield much as much of the TNT's power radiating out into the rest of the world. But given the maximum power capacity is 10 million EU, you'd need a lot of TNT to deplete its reserves, assuming it wasn't also powered and replenishing the store!
This makes Forcefields the king of Blast control and bombproofing (Not including the oil bug). Assuming a blast isn't able to hit the projector/core (The injector simply inputs power so can be destroyed without dropping the Field) and enough power, the Forcefield will survive and shield everything on the other side from the Blast. However, if the shield forms around pre-existing blocks, these become liabilities, your Forcefield is indestructable, but that block of stone isn't! Blasts are capable of destroying blocks in your field and radiating through before the Forcefield updates and closes the hole!
Note: So far, forcefield blocks have proven to be completely indestructible. The only way to shut it off is to do enough damage to drain the 10million power stored in the core as well as however much power it's being provided with each tick. This means that it is possible to lock yourself within the forcefield if you are using simple levers. For example, if you have a cube shaped shield made out of 6 MFFS Deflectors, so a blast inside (such as from a reactor) does not shut off the shield, and you flip the lever outside the field while standing inside the shield, the only way to get out is to have someone else shut it off, be teleported out, or by dying.
Creative mode is capable of destroying a forcefield block until its next refresh (less than a second generally, depending on size) whereupon the block reappears. This is sufficient time to move/fall into the block (horizontal movement would require 2 blocks broken at once however) akin to being stuck inside glass blocks.
Be warned. The Destruction Catalyst's effect continues through the forcefield, demolishing blocks in its path, including valuable things such as the projector, which would drop the forcefield. Giving you a method to escape being trapped or to bypass someone else's security. The Void Ring teleport function is another way through. Equivalent Exchange rounds the position to an integer, meaning that the character ends up in the field and can thus walk through. This only works in 2 of the 4 compass directions. A zapper upgrade can defeat this With knockbackk.
Forcefields are great for bombproofing Nuclear Reactors. An area projector is safe to use. The projector block itself will not be destroyed, although its source of Redstone will, and the field itself will stay up long enough to withstand the entire nuclear blast. Using a box made of external projectors, such as the Deflector or the Directional projector is ideal,the shield will stay up during and after the blast. A six-chambered nuclear reactor filled completely with Uranium Cells takes ~2.5 million of the internal forcefield power.
They are not completely Nuke proof, however, it will take several of them to do anything noticeable. If they all explode at exactly the same time (i.e. they were ignited simultaneously by one lever or wire), the field will theoretically take an infinite number of nukes. However, if they explode at diffrerent times (e.g. one explodes, ignites a few more, they explode, ignite the rest), it only takes 7 nukes to drain the core of its 10 million stored power. If the core is not being fed more EU, the 8th nuke will damage the surrounding area unhindered.
If it is continuously powered, however, it appears to be able to take a much larger amount of explosive force. 4 HV Solar Arrays powering 6 Deflectors creating a 5x5x5 cube forcefield was able to take 12 nukes going off at different times without any damage to the outside world. 13 nukes resulted in one falling through the bottom of the field and exploding the surrounding area.