The ST201M-D3 is a single-pole miniature circuit breaker from the ST200M series, designed for supplementary protection in accordance with UL 1077 and CSA C22.2 No. 235 standards. It has a rated current of 3.0 A and features a D-type tripping characteristic, with an instantaneous trip range of 10 to 20 times the rated current. This high-performance MCB offers an interrupt rating of up to 10 kA and is certified for both AC and DC applications, with voltage ratings of up to 277V AC and 60V DC for a single pole. The device is calibrated at a high reference temperature of 40 °C, making it suitable for a variety of industrial and commercial applications where reliable overcurrent protection is critical.