How does the tester light up and what is the principle?

The working principle of neon tube of the test pen:

1: First of all, the neon tube of the electric pen uses the induced voltage!

2: In the insulated shell, the test contact, the current limiting resistor, the neon tube and the hand touch electrode are electrically connected, and a shunt resistance branch is set up, so that the test contact is electrically connected with one end of a shunt resistor, and the other end of the shunt resistor is electrically connected with a identification electrode that can be contacted by the human body. When the human hand touches the identification electrode and the hand-touched electrode at the same time, the shunt resistor is connected in parallel during the test contact, current-limiting resistor, neon tube, and hand-touched electrode circuit test, the human hand only touches the hand-touched electrode, and the neon tube glows, indicating that the measured object is electrified.

When the human hand touches the electrode and the identification electrode at the same time, if the object under test has a non-dangerous high potential, because the internal resistance of the potential source is very large, which greatly reduces the charged potential of the object, the neon tube does not glow, and if the object under test has a dangerous electric shock voltage, because of its small internal resistance, the access shunt resistance almost does not reduce the charged potential of the DUT, then the neon tube maintains the glow, so as to achieve the purpose of distinguishing the safety voltage.

In this way, the fire wire--- the electric tester (neon tube) - the human body --- the earth constitute a circuit. So it shines.

Have you ever used a tester? Why does it light up when you touch it when you touch it when you connect it to the live wire?

To put it simply. There is a metal sheet in the middle of the tester composed of a neon bubble, a safety resistor and a spring, when the human body holds down the metal sheet to contact the charged body, it is equivalent to forming a loop with the earth to make the neon bubble shine Even if you wear insulated shoes, the leakage of insulated shoes is enough to make the neon bubble glow.

The working principle of the electric tester: there is a neon bubble in the pen body, if the neon bubble glows during the test, it means that the wire is electric or the live wire of the path.

Specifically:

Its internal structure is a bulb with two electrodes, the bubble is filled with neon gas, commonly known as neon bubble, one pole of it is connected to the tip of the pen, and the other pole is connected to the other end of the pen after reading a high resistance. When the voltage between the two poles of the neon bubble reaches a certain value, a glow will be produced between the two poles, and the intensity of the glow is proportional to the voltage between the two poles. When the charged body voltage to the ground is greater than the glow voltage at the beginning of the neon bubble, and when the tip of the pen of the voltage tester touches it, the other end is grounded through the human body, so the voltage tester will emit light.

The nib and tail of the pen are made of metal materials, and the barrel is made of insulating materials. When using the tester, be sure to touch the metal part at the end of the tester with your hands, otherwise, because the charged body, the tester, the human body and the earth do not form a loop, the neon bubble in the tester will not glow, resulting in misjudgment, thinking that the charged body is not charged.

Regardless of the appearance, the construction principle of the voltage tester is basically the same, and its shell is mostly a plastic insulator, which is composed of a metal conductor, a small bulb and a resistance wire.

The small bulb is filled with a colorless inert gas (neon gas) that can produce strong transmission of red light under the excitation of the electric field, when the object is charged, use an electric pen to test the neon bubble redness, otherwise the neon bubble is not bright.

direct test: direct measurement.

Induction Break-Point Test: Induction breakpoint measurement.

First pass the wire to the live wire, not the zero line, and then move the electric pen along the outer skin of the wire, the electric pen will show a sign with induction electricity, and then you keep walking along the wire, knowing that the sign disappears, disappearing, **is the breaking point.

A voltage tester, also known as a voltage tester, is an electrician's tool used to test whether a wire is electrified.

According to the high and low of the measured voltage:

High-voltage voltage tester: used for 10kv and above project operations, for the electrician's daily testing tools;

Low-voltage voltage tester: used for live body detection of line voltage 500V and below.

Weak current voltage tester: used for the test of electronic products, the general test voltage is 6V--24VFor ease of use, the pen often has a lead wire with a clip at the end.

According to the contact method, it is divided into:

Contact voltage tester: a detection tool that obtains electrical signals by contacting a charged body. Usually the shape is a flathead screwdriver, and it is used for both a test pen and a flathead screwdriverFountain pen type, which displays the measurement data directly in the LCD window.

Inductive Voltage Tester: Inductive testing without physical contact to check the voltage on control wires, conductors and sockets or to check the location of open circuits along conductors. It can greatly ensure the personal safety of inspectors.

The working principle of the electric tester is that the small bulb of the pen is filled with a colorless inert gas (neon gas) under the excitation of the electric field, which can produce a strong transmission of red light, when the object is charged, use the pen to test the neon bubble redness, otherwise the neon bubble is not bright.

The front end of the electric detector is a metal probe, which is used to make contact with the equipment being tested. The back end is also a metal object, which may be a metal hook or a metal piece, which is used to make contact with the human body. In the middle of the insulating tube is a neon lamp that emits light, a resistor and a pressure spring.

Regardless of the type and structure of the tester, they work the same.

The voltage detector is divided into three categories according to the different voltages measured: the high-voltage voltage detector can be used to detect items with a voltage of more than 10kV;The low-voltage voltage detector is suitable for the detection of live facilities with a voltage range of less than 500V; When the test voltage range is between 6 and 24V, people often use a weak current tester.