Current Unbalance Protection Time Setting

It will depend on your application.

if you have a balanced load i.e. pump then you can look for small differences with a quick time pick up.

if you have an unbalanced load i.e. crusher, then i suggest you look at the manufacturers data and find what the expected unbalance is so you can set the protection to operate outside of the bandwidth thus avoiding any nuisance trips but protecting the equipment before damage is done.

you also need to make sure you protection is discriminated with upstream current unbalance protection ...if there is any.

you can go 0.15 Im with time as 1 TMS. Bcoz in practical, there will be always some % I2/I1. i think wat you mentioned in the "Time" is TMS since you have said the element is IDMT Charectersitics

Thanks! But, can you trace it back to some Standards as to the withstand capacity of motors for current unbalance?