The Model 777-KW/HP-P2
has the underload trip, adjustable on the face of the unit, based on power, while all the other products in the 777 family provide an undercurrent trip.  The underpower trip feature is desirable anytime the current vs. load characteristic is non-linear or has little change. In general terms, smaller motors and slow speed motors have little change in current over the normal load range. Larger motors that are running light loads will also show small current changes over the operating load range.  KW/HP products should be used with all small centrifugal motors and fractional horsepower motors when underload protection is needed and with most motors under 3hp.  Also use KW/HP products when the motor is derated (Ex: Coal bed methane well with a 7.5hp submersible pump on a 10hp motor.) Other typical applications are mixer motors up to 50hp and beyond that run at less than 1800 rpm, magdrive pumps and can pumps. If in doubt, underpower can be used anytime in place of undercurrent protection.  The 777-KW/HP-P2 can display kilowatts and horsepower and a high power trip feature that can be enabled over a network. The high power trip is useful added protection for positive displacement pumps in a restricted flow (dead-head) condition.