This sample Rulesheet uses .addSeconds in a Nonconditional rule to add 90 seconds to the value of timeOnly2 and assign the result to timeOnly1.
SAMPLE RULETEST
A sample Ruletest provides values of timeOnly2 for three instances of Entity1. Input and Output panels are shown below. Notice how the time wraps around to the beginning of the day, even though Time data type does not include date information.