How to could I get the total time usage using time?

Considering I have time in and time out using the time format HH:MM:SS XM. Now I want to get the difference(Total_Appliances_Usage) between the time in and time out. Can anyone help me tyty.

The block im using to get the current time.

How could I set time format into HH:MM:SS only?

This is the computation I’m assuming:

2:11:55 AM time in
2:15:55 AM time out
Total_Appliances_Usage = 4 mins

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