General Electric Co.s largest union plans to ask for guaranteed pensions that would allow union members to retire after 30 years of service, regardless of age, said Lauren Asplen, spokeswoman for the International Union of Electronic-Communications Workers. She said the union and GE will begin labor negotiations May 19. The current contract runs out June 15. Tim Benedict, GE spokesman, did not return calls seeking comment by press time. The Stamford, Conn.-based pension fund has $36.7 billion in total assets.