The purpose of the voltage test pen_How to use the voltage test pen accurately
The voltage test pen is one of the tools commonly used by electricians to determine whether an object is charged. Its internal structure is a light bulb with only two electrodes. The bulb is filled with neon gas, commonly known as a neon bulb. One pole of it is connected to the tip of the pen, 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 the neon bulb reaches a certain value, a glow occurs between the north and south poles, and the intensity of the glow is proportional to the voltage between the north and south poles. When the voltage of the charged object to ground is greater than the glow voltage at the end of the neon bulb, and the top of the test pen is touched to it, the other end is grounded through the human body, so the test pen will glow. The function of the resistor in the electric test pen is to bind the current flowing through the human body to prevent the occurrence of special risks.
In addition to being able to determine whether an object is charged, the voltage test pen also has the following uses:
(1) It can be used to conduct low-voltage phase verification and measure whether any conductors in the line are in phase or out of phase. The specific method is: stand on an object insulated from the earth, hold a test pen in each hand, and then check the two wires to be tested. If the two test pens glow very brightly, the two wires are different. phase; otherwise, it is in the same phase, which is based on the principle that the voltage difference between the north and south poles of the neon bulb in the test pen is proportional to the intensity of its luminescence.
(2) Can be used to differentiate between AC and DC. When testing with an electric test pen, if both poles in the neon bulb of the electric test pen light up, it is AC current; if only one of the two poles emits light, it is DC current.
(3) Able to distinguish the positive and negative poles of direct current. Connect the test pen to the DC circuit to check. The bright pole of the neon bulb is the negative pole, and the non-lit pole is the positive pole.
(4) Can be used to determine whether DC is grounded. In a DC system insulated from the ground, you can stand on the ground and touch the positive or negative pole of the DC system with a test pen. If the neon bulb of the test pen does not light up, there is no grounding phenomenon. If the neon bulb lights up, it means there is a grounding phenomenon. If it lights up at the top of the pen, it means the positive electrode is grounded. If it lights up at the end of your finger, it means the negative pole is grounded. However, it must be pointed out that in a DC system with a ground monitoring relay, this method cannot be used to determine whether the DC system is grounded.
How to use the voltage test pen accurately:
① Before checking whether the electrical appliances and circuits are live, you should try it in a live place to see if the test pen is intact to prevent errors and electric shock.
②When holding the pen, press the tail of the test pen with your fingers, and grab the pen body with your other fingers.
③When measuring electricity, touch the tip of the pen to the test object and touch the tail of the electricity test pen with your hand. If the test object is charged, the neon tube of the electric test pen will glow; if the neon tube does not glow, it means that the test object is not charged.
④ Test pens whose insulation resistance is less than 1 megohm cannot be used.
