Multiple phase switching circuit and heat sink structure

A three-phase electrical switching apparatus comprising, a generally rectangular bottom member, a top member constructed from an electrically non-conductive material, said top and said bottom members being separated and maintained in generally parallel places by connection to at least two parallel support members oriented generally perpendicular to said top and said bottom, a first and a second pair of inverse parallel connected silicon control rectifiers electrically connected respectively between a first and a second phase of an electrical power supply and a first and a second phase of an electrical load, a third phase of said power supply being connected to a third phase of said electrical load, said first pair of silicon control rectifiers being releasably secured to a first of said parallel support members and said second pair of silicon control rectifiers being releasably secured to a second of said parallel support members, said silicon control rectifiers having a switching means which is responsive to and electrically connected with an external logic source, said two parallel support members and said bottom member being constructed from a heat conductive material, and said electrical power supply, said electrical load and said external logic source being releasably connected to components of said apparatus by terminals releasably secured to said top member.