download this : http://minecraft.curseforge.com/projects/powerconverters-portablejims-fork/files/2255087 put it in your mods folder and it fix the issue.
BEWARE it will destroy all your PowerConverters3 blocks as they do not have the same id. Make a backup to be sure before installing.
I don't understand why tekkit is using a 2 year old library but ok... This a fork from Portablejim updated in September of this year
This also fixes problem with the different tiers of Consumers exploding, and it adds steam compatibility as a bonus