Emi filters on arcade ISO's, whats the purpose?

[abispac]

So inmy last adquisition, i got me a k7000 monitor and it came with an isolator, not that isolator, has an emi filter, but to be honest, i dont understand emi filters, plus it has a harness thathas many cables, i really dont know what they do, i know i can use the iso by itself with the monitor, but this filter was wired to an on off switch.Now the way it was conected, it has an electrical cord on 1 side that goes to electricity, on the other side, the red and blue goes to the monitor, the yellow has a fuse holder but cant tell where it goes as it is by itself, and the green is ground so im not sure what to do with bot blacks that are on top of the emi filter, my guess is thats one onf the electrical  main wires, as the other white goes trhu the harnes, so perhaps both blacks on top of the filter are the - and + for the electricity where one of those goes to the yellow one to use the fuse a safe emeasure? thanks for any help.