The internal composition of the tester and the hazards of a damaged tester
If the resistance of the measuring pen is broken, what will happen when measuring the live wire? The probability of electric shock is relatively high, because whether it is a decrease in internal resistance or an open circuit, it will cause people to misjudge and carry out live operations.
Internal composition of measuring pen
The traditional type of measuring pen has a simple structure, consisting of a high resistance resistor, a neon bulb, a spring, and a pen cap. The neon bulb does not emit light at low voltage and can only light up at 100V or above. It is difficult to damage it if it is not dropped.
The resistance value of high resistance resistors varies. In theory, a value greater than 500k ohms is sufficient to meet the demand. However, we hope that the larger the resistance value, the better. Of course, it cannot be infinitely large, which will open the circuit. When measuring charged objects, it will not emit light, which can easily lead to misjudgment. Therefore, the electric pen needs to be checked and maintained regularly.
So what if the resistance inside the electric pen is lower than the set value? It is obvious that electric pens are prone to electric shock when in contact with charged objects, and I believe that everyone, especially electricians, has learned this lesson.
The hazards of damage to the measuring pen
The misjudgment caused by infinite resistance may lead us to believe that the electrical appliance is dead, posing a risk of electric shock during maintenance operations and causing great harm to human life.
A measuring pen with a resistance lower than 500k ohms can cause a tingling sensation when measuring charged objects. If the resistance is lower, it is equivalent to touching the live wire with your hand, and the consequences are very serious.
summary
When purchasing a measuring pen, you can bring a multimeter to check the resistance of the internal resistor, which is generally above M Ω level, indicating that the quality is excellent and can be used for a long time.
