Schneider Electric C166MA150 Trip unit MA150 for ComPacT NSX 160/250 circuit breakers, magnetic, rating 150A, 4 poles 4d. Official Schneider characteristics include Range: ComPacT; Range of product: ComPacT NSX100...250; Product or component type: Trip unit; Trip unit name: MA; Trip unit technology: Magnetic; Range compatibility: ComPacT NSX160 ComPacT NSX250; Device application: Motor; Poles description: 4P.