(1) Determine the presence or absence of voltage. When testing the object under test, if the neon tube of the test pen is on, it means that the object under test has a voltage, and the voltage is not lower than 60V. Use a test pen to test the metal casings of electrical equipment such as motors, transformers, power tools, washing machines and refrigerators. If the neon tube glows, it means that the casing of the equipment is charged (the power phase wire is short-circuited with the casing).
(2) Determine the voltage level. During the test, the higher the measured voltage, the brighter the light emitted by the neon tube, and an experienced person can judge the approximate voltage range according to the intensity of the light.
(3) Determine the phase wire (live wire) and the neutral wire (earth wire). The neon tube will light up when the electric pen measures the phase line, but the neon tube will not light up when the zero line is measured.
(4) Determine alternating current and direct current. When testing a charged body with a test pen, if the two electrodes of the neon tube emit light at the same time, it means that the measurement is alternating current; if only one of the two electrodes of the neon tube emits light, the measurement is direct current.
(5) Determine the positive and negative poles of direct current. Connect the test pen between the positive and negative poles of the direct current, as shown in Figure 2-14, that is, the probe of the test pen is connected to one pole of the direct current, the metal pen is connected to the other pole, and the glowing end of the neon tube is the negative pole of the direct current.
