ACST-257-1 is a current sense transformer from the ACST-200 series designed for AC current sensing applications. It features a 1:150 turns ratio with an output of 13.9 mV/A ±5%, a maximum load resistance of 2 Ohms, and operates within a primary sense frequency range of 50-200Hz. The transformer supports a primary current range of 0.4 to 30A with a maximum primary resistance of 600 microohms, sense resistance of 1.7 Ohms ±10%, and sense inductance of 0.06H ±30%. Constructed with UL class B 130°C materials and featuring high-pot isolation of 4000V primary-to-secondary, it operates reliably from -40°C to +70°C at full 30A capacity. This current sense transformer is ideal for power monitoring, energy metering, and current measurement applications requiring accurate and isolated current sensing.