Use a test pen to touch the live wire and neutral wire respectively:
①The neutral wire will not respond and the light will not turn on because the neutral wire is directly connected to the earth. ;
② When the test pen contacts the live wire, the light will turn on, because the live wire itself is live. When the test pen contacts the live wire, current flows. through the test pen through the human body then to the earth.
How to use a test pen to identify live wire and neutral wire:
1. First of all, the equipment to prepare for testing is: two resistors (one. -half watt and 680K), an electric pen, plastic copper core hard wires, a single pole double throw switch and a plug power cord.
2. Precautions for using the test pen:
(1) When using the test pen, be sure to alwaysdear the metal part at the end of the test pen with your hand, otherwise, the charged body and the test pen may The electric pen, the human body and the earth do not form a circuit, and the neon bulb in the test pen will not emit light, causing error in judgment and thinking that the charged object is not charged, which is very dangerous.
(2) Before using the test pen, first check whether there is a safety resistance in the test pen, then visually check whether the test pen is damaged, s It is affected by moisture or water, and it can only be used after passing inspection.
A test pen is also called a test pen, or “electric pen” for short. This is an electrician's tool used to test whether electrical wires are live. There is a neon bulb in the pen body. If the neon bulb glows during the test, it means the wire is electrical or it isacts as a live wire in the path. The tip and tail of the test pen are made of metal materials, and the pen body is made of insulating materials.
When using the test pen, be sure to touch the metal part at the end of the test pen with your hand, otherwise, because there is no circuit between the charged body, the test pen and the human body. and the ground, the neon bulb in the test pen will not emit light, causing error in judgment, thinking that the charged object is not charged.
Detailed information:
Uses
In addition to In In addition to determining whether an object is charged, it also has the following uses:
(1) It can be used to perform a low voltage phase check and measure whether line conductors are in phase or off. phase. The specific method is: stand on un object isolated from ground, hold a test pen in each hand, then test the two wires to be tested. If both test pens glow very brightly, the two leads are otherwise in phase; , it's the same phase.
It is based on the principle that the voltage difference between the two poles of the neon bulb in the test pen is proportional to the intensity of its luminescence.
(2) Can be used to distinguish between alternating current and direct current. When testing with a test pen, if both poles of the neon bulb of the test pen light up, it is alternating current; if only one of the two poles emits light, it is a direct current;
(3) The positive and negative poles of direct current can be determined. Connect the test pen to the DC circuit to test. The illuminated pole of the neon bulb is the negative pole and the unlit pole is the positive pole.
(4) can be used to determine if the current continu is grounded. In a ground isolated DC system, the station can touch the positive or negative pole of the DC system with a test pen on the ground. If the neon bulb of the test pen does not light up, there is no grounding phenomenon.
If the neon bulb shines, it means that there is a grounding phenomenon. If it glows like the tip of the pen, it means the positive electrode is grounded. If it lights up on your fingertip, it means the negative pole is grounded. It should be noted, however, that in a DC system with a ground monitoring relay, this method cannot be used to determine if the DC system is grounded.
The voltage test pen is one of the tools frequently used by electricians to determine whether an object is charged. Its internal structure is a bulb with two electrodes. The bulb is filled with neon gas, commonly known as a neon bulb. A polee is connected to the tip of the pen and the other pole is connected in series with high resistance. then connected to the other end of the pen. When the voltage between the two poles of the neon bulb reaches a certain value, a glow occurs between the two poles and the intensity of the glow is proportional to the voltage between the two poles.
When the voltage of the grounded charged object is higher than the initial glow voltage of the neon bulb and the tip of the test pen touches it, the other end is switched to the earth through the human body, so that the test pen will glow. The function of the resistance of the electric test pen is to limit the current flowing in the human body to avoid danger.
Reference materials:
Baidu Encyclopedia-Electric pen