The PowerPacT? H-, J-, and L-frame circuit breakers are designed to protect electrical systems from damage caused by overloads and short circuits. H- and J-frame circuit breakers are available with either thermal-magnetic or Micrologic? electronic trip units. L-frame circuit breakers are available with Micrologic electronic trip units only. Shunt Trip (MX). Trips the circuit breaker when the control voltage rises above 70% of its rated voltage. Impulse type ? 20 ms or maintained control signals. AC shunt trips are suitable for ground-fault protection when combined with a Class I ground-fault sensing element. Continuous duty rated coil.