AUTOMATIC LOAD TRANSFER SWITCH AND CONTROL METHOD THEREOF

摘要

An automatic load transfer switch and a controlling method thereof are provided to protect a motor and a three-phase transformer from damage by detecting an open-phase and a current unbalance due to the open-phase. An automatic load transfer switch(1) is connected between a first power source and a second power source for replacing the first power source. The automatic load transfer switch converts automatically the power. The automatic load transfer switch includes three phase current transformers and a controller(10). The phase current transformers is connected with a three-phase line which is commonly connected with the first and second power sources. The phase current transformers detect phase currents. The controller compares one phase current value with other two phase current values. The controller determines an open-phase according to the compared result. The controller replaces the power with the alternative power.