(1) It can be used for low-voltage phase verification to measure whether any wires in the line are in phase or out of phase. The specific method is: stand on an object insulated from the earth, hold a test lead in each hand, and then test on the two wires to be tested. If the two test leads glow brightly, the two lead wires are different. On the contrary, it is the same phase, which is judged by the principle that the voltage difference between the two poles of the neon bulb in the test pen is proportional to its luminous intensity.
(2) It can be used to distinguish between alternating current and direct current. When testing with a test pen, if both poles in the neon bulb of the test pen glow, it is alternating current; if only one of the two poles glows, it is direct current.
(3) It can judge the positive and negative poles of direct current. Connect the test pen to the DC circuit for testing, the pole that glows on the neon bulb is the negative pole, and the pole that does not shine is the positive pole.
(4) It can be used to judge whether the DC is grounded or not. In a DC system that is insulated from the ground, you can stand on the ground and touch the positive or negative pole of the DC system with a test pen. If the neon bulb of the test pen does not light up, there is no grounding phenomenon. If the neon bulb lights up, it means that there is a grounding phenomenon, and if it lights up like a pen, it means that the positive electrode is grounded. If the light is on the finger end, it is the negative ground. However, it must be pointed out that in a DC system with ground monitoring, this method cannot be used to judge whether the DC system is grounded.
