Trip Units (STR)
Electrical Distribution Equipment
The D trip unit has an Io and Ir dial which together set the rated current of the breaker.
The DP trip unit has a rating plug (ratings from 50% to 100% of the sensor rating) which together with the Ir dial set the rated current.
STR28D (long-time = 0.4x1 sensor rating)
STR28DP (long-time = 0.8x1 plug rating)