... or Double bearing, brushless, Self-excited. Abounds with almost every model in stock. Frequency And Voltage50Hz or 60Hz as per customer ... optional but the rated power will decrease 5%. Voltage RegulatorsThe model we use including: MX321, MX341, AS440, SX440, SX460, etc.Main ... %7) Wave aberration rate of voltage THD≤3%8) Telephone harmony wave factor of telephone THF≤2%9) Telephone effective factor ...