Voltage presence indicator for safety application in electrical panel

A voltage presence indicator for providing warning of a hazardous electrical voltage on a circuit powered by a plurality of electrical power input lines, wherein the voltage presence indicator comprises:

• a. plurality of high impedance bi-directional current paths where plurality of cross coupled depletion MOSFETs offers variable impedance based on the applied input voltage wherein AC clipped voltage across the common cathode configured zener diode provides constant clipped AC voltage needed for the operation of flasher circuit which drives LEDs, for the whole operational input voltage range;
• b. plurality of rectifying paths in which a part of main circuit component current flows through the branch circuit comprising of full bridge rectifier circuits and filter capacitors associated with full bridge rectifier circuits
• c. plurality of sensing resistor network comprising equal value and high impedances connected in star fashion wherein each set resistors of the sensing resistor network is communicating with the phase lines to sense the unbalance condition;
• d. plurality of signal conditioning circuits which processes the voltage at the junction points of sensing resistor network to provide signal voltage to the comparator to trigger flasher circuit of neutral or ground wire;
• and
• e. plurality of high impedance discharge resistors placed across the capacitor present in signal conditioning circuit which discharges the parallel connected capacitor and helps in reducing the voltage available at the positive input pin of comparator during the condition of restoring the balanced voltage condition from unbalanced condition, thus making the corresponding flasher extinguished;
• wherein, the set resistor connected at the junction point of sensing resistor network to tune the percentage unbalance voltage value at which the flasher circuit starts giving indication for unbalance condition.