A: The Voltage Indicator Circuit operates by using high-impedance pathways to detect voltage across phase conductors and ground. Each LED in the circuit is powered by a small current that flows through an internal resistor network, allowing for continuous voltage presence indication.
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High-Impedance Design – The circuit contains a high-impedance resistor network, ensuring minimal current draw while still allowing LEDs to illuminate. This design allows the device to function passively without interfering with system operation.
- Passive Monitoring – The circuit does not require an external power source or active electronics; it relies solely on the system voltage to drive indication. This ensures reliable, always-on voltage detection.
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LED Behavior Under Normal Conditions – In a balanced 3-phase system, all phase LEDs remain illuminated, while the ground LEDs typically remain off. However, if a phase is lost, disconnected, or significantly unbalanced, the ground LED circuit may activate due to the resulting shift in system potential. Please refer to the Ground LED FAQ for more information on what behavior can cause the Ground LED to be illuminated.
For a more in-depth explanation of voltage detection principles, phase imbalance effects, and system-specific behavior, refer to our Voltage Indicator Technical Note.