A fluorescent light starter acts as a timed switch that preheats the fluorescent tube's filaments to facilitate ignition.
Here's a breakdown of the process:
-
Initial State: When the fluorescent light is first switched on, the starter completes a circuit, allowing current to flow through the ballast and the filaments (electrodes) at each end of the fluorescent tube.
-
Heating the Filaments: The current flowing through the filaments heats them up. This heating process is crucial for ionizing the gas inside the tube, making it conductive.
-
Starter Switch Opens: Inside the starter is a small, sealed glass bulb containing a bimetallic strip and an inert gas (often argon or neon). The current flowing through the starter heats the bimetallic strip. After a short delay (typically a few seconds), the bimetallic strip bends due to the heat, causing the starter switch to open.
-
Voltage Surge: When the starter switch opens, the current flow is interrupted. The ballast, which is an inductor, resists this change in current. This resistance creates a high-voltage surge (inductive kick) across the fluorescent tube.
-
Ignition: The high-voltage surge ionizes the gas within the fluorescent tube, creating a path for the electric current to flow between the filaments. This causes the tube to strike and emit light.
-
Starter Deactivation: Once the fluorescent tube is lit, the voltage across the tube drops significantly. This lower voltage is not sufficient to maintain the glow discharge within the starter. The bimetallic strip cools down, and the starter remains in its open state, no longer participating in the circuit.
-
Continuous Operation: The current now flows through the ballast and the lit fluorescent tube, bypassing the starter.
In summary, the starter's role is to:
- Preheat the filaments to vaporize mercury inside the tube.
- Interrupt the circuit to create a voltage surge.
- Trigger ionization of the gas, allowing the lamp to light.
- Deactivate and remain out of the circuit once the lamp is running.
If the fluorescent tube fails to light, the starter will repeatedly attempt this cycle until either the tube ignites or the starter fails. A flickering fluorescent light often indicates a failing starter or a failing fluorescent tube.
