An electromagnetic pulse (abbreviated as EMP) is a short burst of intensive fluctuating magnetic field that disables all electronics for some time, mostly proportional to targeted ship size. Whilst these systems can be highly effective in combat if utilized correctly, they are also harmless by themselves; as the pulse will not deal any damage to ships it disables.
EMP generators are commonly used by ships of various navies, and reached peak popularity during the Homeworld 2 Era, where the two major sides of the conflict were in possession of ships capable generating EM pulses.
Electromagnetic pulses are created from power delivered by the ships main power systems. It has relatively long recharge time, as it requires lots of energy, and the power systems had to deliver energy to other systems of the ship. The charged pulse is released in the form of a projectile (similar to a Plasma Bomb) which explodes after hitting an enemy unit, or after a given time (which allowed ships to aim their EMP in the centre of enemy formations).
EMP technology was used by Kiith Somtaaw ACVs. This vessel, thanks to the combined power of two Acolyte powerplants, was capable of generating a strong pulse, disabling all the units around it. EMP systems were placed around the whole corvette, releasing a circular pulse.
Most commonly, however, electromagnetic pulses were used during Vaygr War when the Vaygr and Hiigaran fleets possessed small EMP launchers. These required a long time to charge, but a single wing of scouts was capable of disabling several fighters and corvettes, or even frigates, for long enough to provide a crucial advantage. The EMP devices could even be used against the Keepers with a reasonable chance of success; if successful, it would force the Keeper to temporarily withdraw from battle.
Strangely, in Homeworld 2, only the scouts can launch the EMP. Bombers are designed to launch bombs, so they should have access to these bombs. The fact that only scouts have these bombs makes try to use them for offensive purposes without support is almost useless because of the weak weaponry. In addition, the scouts are easily destroyed and can place an attack depending on the EMP at risk.