HID magnetic ballasts consist of robust core and coil designs that meet or exceed minimum ANSI requirements. These ballasts are typically sold as distributor replacement kits which are pre-wired with a capacitor, ignitor (if applicable) and all necessary mounting hardware and instructions. Each wattage is typically offered in quad (MLT-120/208/240/277 volt), 5-tap (ML5-120/208/240/277/480 volt) or 480 volt (48T) options.
A high-pressure sodium (HPS) ballast is an electrical device used to regulate and control the flow of electrical current to a high-pressure sodium lamp. High-pressure sodium lamps are a type of high-intensity discharge (HID) lamp that produce light by passing an electric arc through a mixture of sodium vapor and other gases.
The ballast serves several functions in the operation of a high-pressure sodium lamp:
Starting: High-pressure sodium lamps require a high voltage to initiate the arc. The ballast provides the initial high voltage pulse to strike the arc. This is typically done through the use of an igniter or a high-voltage pulse generator.
Voltage Regulation: Once the arc is struck, the ballast regulates the voltage across the lamp to maintain a stable discharge. High-pressure sodium lamps have a positive temperature coefficient, meaning their resistance increases as the lamp heats up. The ballast compensates for this change by adjusting the voltage to keep the lamp operating within its optimal range.
Current Regulation: The ballast also regulates the current flowing through the lamp. It limits the current to prevent overheating and damage to the lamp. High-pressure sodium lamps require a relatively high current during operation, and the ballast adjusts the current accordingly.
Power Factor Correction: Some high-pressure sodium ballasts incorporate power factor correction (PFC) circuitry to improve energy efficiency. PFC helps align the phase relationship between the voltage and current, reducing reactive power and improving the overall power factor of the system.
High-pressure sodium ballasts are available in different types, including magnetic (core-and-coil) ballasts and electronic ballasts. Magnetic ballasts use an iron core and coil arrangement to regulate the current, while electronic ballasts use solid-state electronic components.
It's important to select a ballast that matches the specific requirements of the high-pressure sodium lamp you are using. Ballasts are typically designed for specific wattages and lamp types, so compatibility is crucial for proper operation and lamp longevity.