In addition to being able to determine whether an object is charged, a test pen also has the following uses:
(1) It can be used for low-voltage nuclear phase measurement to determine whether any wires in the circuit are in phase or out of phase. The specific method is to stand on an object that is insulated from the ground, hold a measuring pen in each hand, and then test on the two wires to be tested. If the two measuring pens light up very bright, then these two wires are out of phase; On the contrary, it is in phase, which is judged based on the principle that the voltage difference between the two electrodes of the neon bubble in the measuring pen is directly proportional to its luminous intensity.
(2) It can be used to distinguish between alternating current and direct current. When using a test pen for testing, if both poles in the neon bubble of the test pen emit light, it is an alternating current; If only one of the two poles emits light, it is direct current.
(3) It can determine the positive and negative terminals of direct current. Connect the test pen to a DC circuit for testing. The electrode where the neon bubble lights up is the negative electrode, and the electrode where it doesn't light up is the positive electrode.
(4) Can be used to determine whether the DC is grounded. In a DC system with ground insulation, you can stand on the ground and use a measuring pen to contact the positive or negative pole of the DC system. If the neon bubble of the measuring pen is not lit, there is no grounding phenomenon. If the neon bubble lights up, it indicates a grounding phenomenon. If it lights up at the tip of the pen, it indicates that the positive electrode is grounded. If it lights up at the fingertip, it is negative ground. However, it must be pointed out that in DC systems with grounding monitoring relays, this method cannot be used to determine whether the DC system is grounded.
A 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, filled with neon gas, commonly known as a neon bubble. One pole is connected to the pen tip, and the other pole is connected in series with a high resistance wire to the other end of the pen. When the voltage between the two poles of a neon bubble reaches a certain value, a glow is generated between the two poles, and the intensity of the glow is proportional to the voltage between the two poles. When the voltage between the charged body and the ground is greater than the glow voltage at the beginning of the neon bubble, and the tip of the measuring pen is in contact with it, the other end is grounded through the human body, so the measuring pen will emit light. The function of the resistance in the measuring pen is to limit the current flowing through the human body to avoid danger.
