A two-lamp electronic ballast for UltraAqua UV systems using 220 W lamps, carried under part number 30271. A UV ballast (lamp driver) is not a simple transformer. It strikes the arc in the lamp and then holds the discharge current constant for the rest of the lamp’s life, because a gas discharge has a negative resistance characteristic and would otherwise draw increasing current until it destroyed itself. Germicidal output is a direct function of that current being held correctly, so a failing or mismatched ballast shows up as under-dose long before it shows up as a dead lamp. This is the version for systems built up to 2009; UltraAqua changed the ballast on later units, so the build year of the reactor decides which one is correct and a visual match is not sufficient. Where a Modbus link to a PLC or SCADA system is needed, the four-lamp unit listed as item 4917-0515 provides one; this unit does not. Supplied by cBallast on quote-to-invoice terms; lead time and freight are quoted per RFQ against the destination Incoterm.