DDSY1352 single phase pre-paid meters with intro-control, DTSY1352 three phase pre-paid meters with intro-control are used for calculating the single and three phase active energy respectively on the frequency of 50 Hz. The meter has functions of pre-paid, load controlling and RS485 communication etc. meet the related technical requirements of electronic power meter in the IEC62053-21, IEC62053-22 standards.