Replacement lamp ballast for the Trojan UVLogic AS reactor, supplied against original Trojan part number 903988-01, and listed for the UV Logic 03AS20. 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. The wider-fitment equivalent is item 1522-0306 (UVLogic AL), which carries the same original part number but is listed for the 06AL30 and several UVSwift SC reactors in addition to the 03AS20. If your reactor is not a 03AS20, check that item first. Supplied by cBallast on quote-to-invoice terms; lead time and freight are quoted per RFQ against the destination Incoterm.