Why does the test pen not illuminate when it measures the zero line?
Not only does the current flow through, but it is also equal to the current in the live wire, because the neutral wire is connected in series with the live wire and the consumer, and the current in each part of the series circuit is equal. If you don't believe me, test it with an ammeter. As for why it can't be detected with the electric test pen, it is very simple, because the electric test pen is used to distinguish the live wire and the neutral wire, or to judge whether the conductor is connected to the live wire, and cannot judge whether there is current. When the metal body of the test pen tip touches the live wire or the conductor connected to the live wire, a loop is formed from the live wire through the test pen, the human body to the earth, because there is a 220V voltage between the live wire and the earth, there is a weak current from the live wire through the test pencil and the human body Flowing to the earth, the neon tube of the test pen emits light, but it is not the same as the current in the live wire. When the metal body of the pen tip of the test pen touches the zero line, since there is no voltage between the zero line and the earth, no current will flow through the test pen, and the neon tube of the test pen will not emit light.
How to use the digital display test pen?
(1) Button description:
(A key) DIRECT, direct measurement button (far away from the LCD screen), that is, when using the pen tip to directly touch the line, please press this button.
(B key) INDUCTANCE, inductive measurement button (closer to the LCD screen), that is, when you touch the line with the tip of the pen, please press this button.
Note: Regardless of how to print on the electric pen, please remember that the one farther from the LCD screen is the direct measurement key; the one closer to the LCD is the sensor key.
(2) The digital display test pen is suitable for direct detection of 12-250 V AC and DC and indirect detection of neutral wire, phase wire and breakpoint of AC power. It can also measure the continuity of dead conductors.
(3) Direct detection:
①The last number is the measured voltage value.
②When the display value of high cut-off is less than 70%, it will display low cut-off value.
③ When measuring direct current, touch the other pole with your hand.
(4) Indirect detection: Press and hold the B key, and bring the pen tip close to the power line. If the power line is charged, the display of the digital display pen will display a high voltage symbol.
(5) Breakpoint detection: hold down the B key and move longitudinally along the wire, the place where there is no display in the display window is the breakpoint.
