Nine functions of test pen application test
Function 1: Identify live wire and neutral wire
This is one of the most commonly used functions of a test pen. When measuring AC circuits:
Touch the wire with an electroscope, the neon bulb glows with the live wire;
Neon bulbs do not emit light is the neutral (or ground).
Function 2: Identify whether there is electricity in the line
This is also one of the most commonly used functions of the electric pen, which is to hold the electric pen in the correct posture and touch the conductor with the tip of the pen. If the light of the electric pen is on, it proves that there is voltage in the circuit, and if the light is not on, it proves that there is no voltage in the circuit.
In actual use, it should be noted that it is not possible to judge whether the circuit is normal only by the fact that the neon bulb of the electric pen does not emit light.
For example, under normal conditions, the live wire and the neutral wire are wrongly connected, and the neon bulb of the electric pen glows.
Ability 3: Measure in-phase or out-of-phase of phase lines
Circuits that do not distinguish wire colors will definitely be a headache when repairing. The single-phase circuit is fine, but if you encounter a three-phase circuit, it is really a big head! However, the electric pen has a magical function that can easily help you measure the in-phase or out-of-phase of the phase line.
When measuring, hold an electric pen in each hand and stand on an insulating object. Touch the two electric pens to the two wires at the same time, if the brightness of the two electric pens is low, it means that the two wires measured at this time are in phase (both phase wires).
Function 4: Check whether the equipment is leaking
Lightly touch the outer casing of the electrical equipment with an electroscope, if the neon tube of the electroscope glows, it means that there is a leakage phenomenon. No light is not.
Function 5: Identify alternating current and direct current
When testing with a test pen:
If both ends of the neon bulb of the test pen glow, it is alternating current;
If only one end glows, it is direct current.
The brightness of the electric pen when measuring alternating current is significantly higher than that of direct current.
Function 6: Identify whether the DC is grounded
In a DC system insulated to the ground, you can stand on the ground and use a test pen to touch the positive or negative pole in the DC system:
If the neon bulb of the test pen does not light up, there is no grounding phenomenon.
If the neon bulb is bright, it means that there is a grounding phenomenon, and if the light is on the tip of the pen, it means that the positive electrode is grounded.
However, it must be pointed out that in a DC system with a grounding monitoring relay, this method cannot be used to determine whether the DC system is grounded.
Function 7: Identify the positive and negative poles of direct current
When measuring direct current, only one end of the neon bulb is lit:
When measuring the positive pole of the DC power supply, the - end of the neon tube near the tip of the pen glows;
When measuring the negative pole of the DC power supply, the end of the neon bulb away from the tip of the pen glows.
Function 8. Judging whether the contact is good
If the neon bulb in the test pen flickers during measurement, it may be due to loose wire ends and poor contact. It could also be because the voltage is not stable.
Function 9. Identify whether the bulb is broken or not
Turn off the light bulb switch. When the light is not on, use a test pen to touch the two terminals of the lamp holder. If both ends make the neon bulb of the electric pen glow, but the light bulb is not damaged, it means that the neutral wire is broken.
