Whether you sleep to public television or classical music, take note. WQED will be interrupting service to Television (Channel 13; and we assume WQEX at Channel 16) as well as WQED-FM (89.3) at 2 a.m. on Tuesday to install emergency power equipment. The interruption is expected to last just three hours. Studio power will be off for the first hour and transmitter power will be off for the remaining two hours. All operations should continue by 5 a.m.