Hi Upender,
The formula below extracts the minutes section from the TimeField and then multiplies it to 60. After the minutes portion of the TimeField has been converted to seconds, I then extracted the seconds portion and simply added it to the previous data.
(substring-before(substring-after(TimeField, ":"), ":") * 60) + (substring-before(substring-after(substring-after(TimeField, ":"), ":"), "+"))
where TimeField is the field which holds the time.
You can also perform this approach to the hours portion - extract the hours and then multiply it to 3600, then add this value to the other values (formula above).
I haven't encountered any way yet to disable the CTRL + Z function since this is a global command or a hot key of some sort.
Hope this helps.