"Safe Use of Electricity" is inseparable from the electricity PPT courseware

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"Safe Use of Electricity" is inseparable from the electricity PPT courseware

home circuit

Home circuits are the circuits that power household appliances, also called lighting circuits. For example, lights, televisions, washing machines, and refrigerators are all powered by household circuits.

Entrance line (live line, neutral line)

(1) The entrance line is led from the outdoor low-voltage transmission line and consists of two lines. One is connected to the ground outdoors and is called the neutral line, and the other is called the live line. When electrical appliances such as lights are connected between the two wires, the electrical appliances will work.

(2) The voltage between the live wire and the neutral wire is 220 volts. There is no voltage between the neutral wire and the ground wire, and there is 220 volts between the live wire and the ground wire.

(3) Household appliances are connected in parallel in the circuit. Each appliance has a switch connected in series between the live wire and the appliance to ensure that the turning on and off of each appliance does not affect the use of other appliances, thus ensuring normal operation. In this case, the voltage of each electrical appliance is 220 volts.

Meter

(1) Function: Measure the amount of electric energy consumed by the user within a certain period of time

(2) The electric energy meter should be installed on the trunk line of the household circuit.

(3) Electric energy meters have different specifications.

If there are many electrical appliances in the home, the current allowed by the electric energy meter should be larger, otherwise it will be burned out.

main switch

Located on the main road of household circuits, knife switches were commonly used in the past. With the development of science and technology, air switches are now used to replace knife switches and fuses.

It has automatic characteristics. When the circuit current is too large due to short circuit and other reasons, it will automatically disconnect and cut off the circuit to protect the safety of electricity.

Fuse: a safety device for a circuit.

(1) Fuses are made of lead-antimony alloy with high resistivity and low melting point.

(2) When the current in the circuit is too large, the fuse will blow first, thereby cutting off the power supply to ensure the safety of the circuit and electrical appliances and avoid fire. Fuses are generally installed in fuse boxes.

Lights and branch switches

Electric lights are essential in household circuits. One end of the lamp is connected to the neutral wire, one end is connected to the switch, and the other end of the switch is connected to the live wire. The lights in each room are connected in parallel between the live and neutral lines. Each light needs a switch control.

3. Safety voltage:

Only voltages no higher than 36V are safe for the human body and are called safe voltages.

Note: Human beings are conductors and can easily allow current to pass through. The harm of current to the human body is related to factors such as the size of the current and the length of time it is energized. When the current passing through the human body reaches 8-10 mA, it is difficult for the human body to get rid of the charged body; when the current passing through the human body reaches 100 mA, it only takes a short time to suffocate the person, stop the heartbeat, and cause an electric shock accident. The greater the current, the shorter the time from electrocution to death. A large number of experiments have shown that voltages below 36V are safe for the human body and are called safe voltages.

Common sense about safe electricity use

1. How people are electrocuted.

(1) Single line electric shock

(2) Double wire electric shock

(3) High voltage arc electric shock

(4) Step voltage electric shock

2. Principles of safe use of electricity

Do not come into contact with low-voltage charged objects.

Do not go near high-voltage charged objects,

Do not use electrical appliances when they get wet.

Does not damage the insulation layer.

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For more information about the PPT courseware "Electricity is inseparable from safe use of electricity", please click the Electricity ppt tag that is inseparable from safe use of electricity.

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Update Time: 2024-07-02

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