Inductor Testing and Fault Diagnosis
Inductors are passive two-terminal electrical components that store energy in a magnetic field when electric current flows through them. A common type of inductor is used in fluorescent lighting circuits, often referred to as a ballast inductor or a "choke". Testing these components involves assessing their ability to store and release energy and checking for internal faults.
Continuity Test
A basic test involves checking for continuity. A functioning inductor should exhibit a low resistance reading (typically a few ohms, depending on the inductor's specifications) using an ohmmeter function of a multimeter. An open circuit reading (infinite resistance) indicates a broken wire or internal fault. A short circuit (zero resistance) suggests a short within the inductor's windings, rendering it unusable.
Inductance Measurement (Advanced Testing)
For more precise testing, an inductance measurement is required. This determines the inductor's ability to store energy. Many multimeters offer this function. The measured inductance should match the inductor's specified value, usually printed on the component itself. Significant deviations may indicate damage or degradation.
Visual Inspection
A visual inspection is crucial. Look for physical damage such as cracks in the casing, burned components, or loose connections. Such damage often indicates internal faults.
Safety Precautions
Always disconnect the component from the circuit before testing. Discharge any capacitors in the circuit before handling the inductor to prevent electrical shock. High voltages may be present in circuits even after power is turned off. Take necessary safety precautions according to established electrical safety practices.
Interpretation of Test Results
- Low Resistance (Continuity): Suggests a potentially functional inductor.
- Open Circuit (Infinite Resistance): Indicates a break in the windings, rendering the inductor faulty.
- Short Circuit (Zero Resistance): Indicates a short in the windings, rendering the inductor faulty.
- Inductance Measurement Discrepancy: A significant difference between the measured and specified inductance suggests degradation or damage.
- Visual Damage: Visible damage usually points towards a fault and should be further investigated.