A time string value is any of the following:
A valid time string enclosed within quotation marks. For example, “11:15:30”.
A reference to a cell containing a valid time string. For example, a reference to a cell containing =”22:10:15”.
A reference to a cell formatted as text that contains a valid time string.
Time values can use the 24-hour format or include am, pm, AM, or PM. Time values of “11:00”, “11:00am”, “11:00 am”, “11:00AM”, and “11:00 AM” are all equivalent. Time values of “23:00”, “11:00pm”, “11:00 pm”, “11:00PM”, and “11:00 PM” are also all equivalent. The use of periods (such as “a.m.”) is not supported.