Power supply zero and live wire detection

刘小天

Power supply zero and live wire detection [Copy link]

     I need help with a zero-live detection circuit for power input. Its function is to detect whether the zero-live wire is plugged back.

btty038

There are many results when searching for Tik Tok online.

chunyang

That depends on whether it is manual detection or automatic circuit judgment. For manual detection, you can connect a neon bulb in series with a current-limiting resistor, connect one end to the power lead, and the other end to a metal contact, and touch the contact to see if the neon bulb glows. This method is best to use a single-pole double-throw switch to select the two power lines separately, so that you can determine which one is the live wire. To automatically detect through the circuit, there must be a ground wire (connected to the earth) loop, and the judgment is based on whether there is a leakage current to the ground. However, this method may misjudge when there is a large voltage to the ground on the neutral line, and excessive current to the ground may cause the leakage switch to operate, so you must carefully choose the appropriate detection current.

懒猫爱飞

Master Chunyang is right, this method can be used to detect

刘小天

OK, thanks for the tip: handshake

刘小天

chunyang posted on 2019-3-11 23:38 It depends on whether it is manual detection or automatic circuit judgment. Manual detection can be done by connecting a neon bulb in series with a current limiting resistor, one end connected to the power lead, and the other end connected to a metal contact...

Can you make an automatic detection schematic?

chunyang

Liu Xiaotian posted on 2019-3-12 11:39 Can you make an automatic detection schematic?

This depends on your system resources and the specific requirements of the application. There is no universal "schematic diagram".

美候王

The circuit diagram of the electric pen is a simple (live wire detection circuit) diagram.

PowerAnts

Meihou Wang published on 2019-3-17 14:31 The circuit diagram of the electric pen is a simple (live wire detection circuit) diagram.

The one with wool is used. The human body forms a loop with the earth. It is a three-wire system, which is much simpler. There must be a two-wire solution. The principle is very simple: get a large area of electrode, and use its distributed capacitance to form a loop with the earth. It is just an extended application of the principle of capacitive screen. As long as it is not far from the earth, this method is omnipotent.