The purpose of the electric tester_How to use the electric tester accurately
A measuring pen is one of the things commonly used by electricians to distinguish whether an object is charged or not. Its internal structure is a light bulb that only requires two electrodes. The bulb is filled with neon gas, commonly known as a neon bulb. One pole of the bulb is connected to the pen tip, and the other pole is connected in series with a high resistor and then connected to the other end of the pen. When the voltage between the north and south poles of a neon bubble reaches a certain value, a glow occurs between the poles, and the strength of the glow is proportional to the voltage between the poles. When the voltage of the charged body to ground is greater than the glow voltage at the beginning of the neon bubble, and the tip of the measuring pen touches it, the other end passes through the human body to ground, so the measuring pen will emit light. The effect of resistance in a measuring pen is to bind the current flowing through the human body and avoid potential hazards.
In addition to being able to distinguish whether an object is charged or not, a measuring pen also has the following uses:
(1) Can be used for low-voltage phase detection, measuring whether any wires in the line are in phase or out of phase. The detailed method is to stand on an object that is insulated from the ground, hold a measuring pen in each hand, and then cross the two wires to be tested for inspection. Assuming that the two measuring pens are emitting light brightly, then these two wires are out of phase; On the contrary, it is in phase, which is achieved by using the principle that the voltage difference between the north and south poles of the neon bubble in the measuring pen is proportional to its luminescence intensity.
(2) Can be used for differential communication between electricity and direct current. When using a measuring pen for inspection, assuming that both poles in the neon bubble of the measuring pen emit light, it is called communication electricity; Assuming that only one of the two poles needs to emit light, it is a direct current.
(3) The positive and negative poles that can distinguish direct current. Connect the measuring pen to the DC circuit for inspection. The positive pole of the neon bubble is the one that lights up, and the one that does not light up is the positive pole.
(4) Can be used to distinguish whether DC is grounded or not. In a DC system insulated from the ground, one can stand on the ground and touch the positive or negative pole of the DC system with a measuring pen. If the neon bulb of the measuring pen does not light up, there is no grounding phenomenon. Assuming the neon bubble is bright, it indicates a grounded phenomenon, and if its brightness is at the top of the pen, it indicates a positive grounding. If it lights up on the finger end, it is negative ground. However, it is necessary to point out that in DC systems with grounding inspection relays, this method cannot be used to distinguish whether the DC system is grounded or not.
How to accurately use a measuring pen:
① Before checking whether the electrical appliances and circuits are live, it is necessary to first test them on a live ground to see if the measuring pen is intact, in order to prevent electric shock caused by differential errors.
② When holding the pen, press down on the tail of the measuring pen with your fingers, and grab the pen body with the other fingers.
③ When measuring electricity, the pen tip touches the inspection body and the hand touches the tail of the measuring pen. Assuming the inspection body is charged, the neon tube of the measuring pen will emit light; If the neon tube does not emit light, it indicates that the inspection body is not charged.
④ Electrical pens with insulation resistance less than 1 megohm cannot be used.
