The principle and use of the electric test pen
The majority of electricians frequently utilize the electric test pen as one of their tools to check whether an object is charged or not. Its interior structure is a neon bulb, which is a bulb with two electrodes and is filled with neon gas. With a high resistance in series, one pole is attached to the tip of the pen and the other pole is connected to the other end of the pen. A light is produced between the two poles of the neon bubble when the voltage between the two poles reaches a specific value. The intensity of the glow is inversely proportional to the voltage between the two poles.When the test pen's tip touches a charged body with a voltage higher than the neon bulb's glow voltage and the other end of the pen is grounded through the body, the test pen will begin to glow. In order to prevent harm, the resistance in the test pen limits the current that can pass into the body.
The test pen can be used for the following things in addition to determining whether something is charged:
(1) It can be used to determine whether any wires in the line are in phase or out of phase using low-voltage nuclear phase measurement. The precise procedure is to hold a test pen in each hand while standing on an object that is insulated from the earth, test the two wires, and then repeat the process. The two wires are different if either of the two test pencils glows brightly. Instead, it is in the same phase, which is determined by the luminous intensity of the neon bulb in the test pen and the voltage differential between its two poles.
(2) It can be utilized to differentiate between direct current and alternating current. When using a test pen, alternating current is present if both poles of the neon bulb glow; if only one of the two poles glows, direct current is present.
(3) Direct current's positive and negative poles can be assessed. The neon bulb that illuminates should be connected to the test pen, and the pole that isn't lit should be connected to the DC circuit to be tested.
(4) It can be used to determine whether or not the DC is grounded. You can stand on the ground and use a test pen to make contact with the positive or negative pole of a DC system that is isolated from the ground. No grounding phenomena exists if the test pen's neon bulb does not light up. The positive electrode is grounded if the neon lamp is bright, which also indicates the presence of the grounding phenomena. The negative ground is present if it glows on the finger end.The method cannot be used to assess whether a DC system is grounded in a system with a grounding monitoring relay, it must be noted.
