Hi,
If you have 24-Hour time format then you can concatenate 00 as below:
=Left(FormatDate([SAHH Start Time];"hhMMSS");2) +":00"
and if you are using 12-Hour format, the you can use below:
=Left(FormatDate([SAHH Start Time];"hhMMSS");2) +":00"+ " Right(FormatDate([SAHH Start Time];"hhMMSS");2)"
Sahil