H switch is also used for setting “hours” in the clock and M switch for setting “minutes”. See 11.1.4-5 “DISPLAY”. PC450-ENG 2-12 11. EXPLANATION OF COMPONE NTS 11.1.5 E: SWITCHES 1. WORKING MODE SELECTOR SWITCH (Basic switch) NOTICE When the breaker is used, never select the H.O. (heavy-duty op- eration) mode.