The utility model relates to an alarm system synthesizes in miniature transformer substation. By following structure composing: the charger, the power supply is organized for the lithium cell to the charger, and lithium cell group tests button, chimes of doom IC and power amplification module to two position relays and 5V boost module power supply, two position relays control involution, and chimes of doom IC sends a signal to the power amplification module, and the power amplification module is connected with the speaker, 5V boost module and circuit connection, the circuit is connected with the LED pilot lamp, is equipped with the input terminal on two position relays. The utility model discloses an advantage effect: through the cable collection at a distance the protection exception always move the node, during the node action, this alarm system reports to the police. This system adopts the hybrid power supply mode, and when external power source lost, automatic switch -over to inside mains operated charged to inside battery when connecting external power source voluntarily. It is small, about suitcase size, convenient to carry.