Introduction to the use of low-voltage electroscope pen
(1) Judging the induction current
When measuring a long three-phase line with a general electroscope pen, even if one phase of the three-phase AC power supply is missing, it can be judged which power supply is missing (the reason is that the line is long, and there is a capacitance between the parallel lines and the line). Existence, so that a wire that lacks a phase generates induction electricity, causing the neon tube of the test pen to light up). At this time, a small capacitor of 1500pF can be connected to the neon tube of the electroscope pen in parallel (the withstand voltage should be greater than 250V), so that the electric pen can emit light as usual when measuring live lines; If it is not bright or slightly bright, it can be judged whether the measured power supply is induced electricity. (The guessing principle is that a small capacitor can release the AC induction current (small current), but cannot release the high-current AC, which is dangerous, so try carefully).
(2) Distinguishing whether the AC power supply is in phase or out of phase
Hold an electroscope pen in each hand, stand on an insulating object, and touch the two pens to the two wires to be tested at the same time. If the neon tubes of the two electroscope pens are not too bright, it means that the two wires are in the same phase; If the neon tubes of the two test pens emit very bright light, it means that the two wires are out of phase.
(3) Distinguish between alternating current and direct current
When alternating current passes through the electroscope pen, the two poles in the neon tube will light up at the same time; while when direct current passes through, only one pole of the neon tube will light up.
