Square D PowerPact P, M and R-frame circuit breakers are designed to protect electrical systems from damage caused by overloads and short circuits Molded case circuit breakers are available with either basic electronic trip system or Micrologic electronic trip units. This external neutral current transformer kit is used for MasterPact T-frame 3 phase, 4wire circuit breakers with current rating up to 1600A with oversized neutral protection as 1.6Ir.