(1) Judging AC and DC Formulas The electric pen determines AC and DC, AC is bright and DC is dark, the AC neon tube is bright, and the DC neon tube is bright at one end. Note: First of all, let the reader know that before using the low-voltage test pen, it must be tested on the confirmed charged body; it should not be used until the test pen is confirmed to be normal. When judging AC and DC, it is best to make a comparison between the "two powers", so that it is obvious. When measuring alternating current, both ends of the neon tube light up at the same time, and when measuring direct current, only one end of the neon tube is extremely bright.
(2) The formula for judging the positive and negative poles of direct current: the electric pen determines the positive and negative poles. Be careful when observing the neon tube. The bright front end is the negative pole, and the bright rear end is the positive pole. Description: The front end of the neon tube refers to the tip of the electric test pen, and the rear end of the neon tube refers to the end of the hand. The bright front end is the negative electrode, and vice versa. When testing, pay attention to: the power supply voltage is 110V and above; if the person is isolated from the earth, touch either pole of the power supply with one hand, and hold the measuring pen with the other hand, the metal tip of the electric pen touches the other pole of the power supply to be tested, and the front end of the neon tube. If it is bright, the power supply tested is the negative pole; if the back end of the neon tube is extremely bright, the power supply tested is the positive pole.
(3) Judging whether the DC power supply is grounded or not, the difference between the positive and negative poles is the DC coefficient of the substation, and the electric pen does not light up; if the light is close to the tip of the pen, the positive pole has a ground fault; if it is close to the finger end, the ground fault is in the negative pole . Note: The DC coefficient of power plants and substations is insulated from the ground. People stand on the ground and touch the positive or negative pole with an electroscope. The neon tube should not light up. If it lights up, it means that the DC system has Grounding phenomenon; if the light is on the end near the tip of the pen, it is the positive ground; if the light is on the end near the finger, it is the negative ground.
(4) Judgment of in-phase and out-of-phase formulas To determine the same difference between two lines, hold a pen in each hand, both feet are insulated from the ground, touch an important line with each pen, and watch a pen with your eyes, if the same phase is not illuminated, it is different. . Note: During this test, remember that both feet must be insulated from the ground. Because most of our country is powered by 380/220V, and transformers generally use the neutral point to be directly grounded, so during the test, the human body and the ground must be insulated to avoid forming a loop to avoid misjudgment; during the test, the two strokes are on and off. The bright display is the same, so just look at one.
(5) To determine the ground fault of the phase line of the 380/220V three-phase three-wire power supply line, the three-phase line of the star-connection method is star-connected. The electric pen touches two lights, and the remaining one is weak. ground fault. Description: The secondary side of the power transformer is generally connected in a Y shape. In a three-phase three-wire system where the neutral point is not grounded, when the three phase wires are touched with an electroscope, two of them are slightly brighter than usual, while the other one is slightly brighter than usual. If the brightness of the phase line is weaker, it means that the phase line with weak brightness has a grounding phenomenon, but it is not too serious; if two are very bright, and the remaining one is almost invisible, it means that this phase line has a metal grounding fault .
