How to Measure Voltage with an Electric Pen
Digital display test pen is a type of test pen, belonging to the category of electrical and electronic tools, used to test whether wires are live. The digital test pen body is equipped with an LED display screen, which can visually read the test voltage numbers. When measuring a live wire, the lighting circuit has a voltage of around U=220V between the live wire and the ground. The resistance of the human body is generally very small, usually only a few hundred to several thousand ohms, while the resistance inside the measuring pen is usually a few megaohms. The current passing through the measuring pen (i.e., the current passing through the human body) is very small, usually less than 1 milliampere. When such a small current passes through the human body, it is not harmful to people, and when such a small current passes through the neon bubble of the measuring pen, Neon bubbles emit light.
Instructions for using buttons:
(A key) DIRECT, directly measure the button (far from the LCD screen), that is, when using the screwdriver to directly contact the circuit, please press this button;
(B key) INDUCTANCE, induction measurement button (close to the LCD screen), that is, when using the screwdriver to induce contact with the circuit, please press this button.
Note: Regardless of how the pen is printed, please recognize that the one far away from the LCD screen is the direct measurement key; The one closest to the LCD is the sensing key!
This test pen is suitable for direct detection of 12-250V AC/DC power and indirect detection of the zero line, phase line, and breakpoint of AC power. It can also measure the on/off of uncharged conductors.
Direct detection:
a. The last digit represents the measured voltage value;
b. When the high break display value is not 70%, the low break value is displayed;
c. When measuring direct current, touch the other pole with your hand;
Indirect detection:
Press and hold the B key, place the batch head close to the power cord. If the power cord is live, the high voltage symbol will be displayed on the display of the digital display pen
Breakpoint detection:
When holding down the B key and moving longitudinally along the wire, the breakpoint is the point where there is no display in the display window.
The new digital display test pen can test 12V, 36V, 55V, 110V, and 220V. Generally, the voltage is measured by the point above the test pen, and the highest display is the current test voltage value; The following is an induction test to detect the open circuit of the insulation circuit, which is based on experience.
Voltage detection:
1. The detection range is 12-250V AC/DC voltage.
2. Gently touch the direct measurement (DIRECT) button, and the metal front end of the test pen contacts the object being tested. The test pen is divided into five voltage values: 12V, 36V, 55V, 110V, and 220V. The last value on the LCD screen is the measured voltage value (when it is less than 70% of the high end display value, the low end value is displayed).
When measuring non ground direct current, hands should contact another electrode (such as positive or negative).
Induction detection:
1. Gently touch the INDUCTANCE button to measure the metal front end of the stylus close to the object being tested. If the "high voltage symbol" appears on the display screen, it indicates that the object has AC power.
2. When measuring a disconnected wire, lightly touch the INDUCTANCE button, and the metal front end of the measuring pen is close to the insulation outer layer of the wire. There is a disconnection phenomenon, and the "high voltage symbol" disappears at the breakpoint.
3. By using this function, it is easy to distinguish between zero and phase lines (increasing the distance between lines when measuring parallel lines). Detect the radiation and leakage of microwaves.
