Three-phase electric water boiler final control and protection device

Abstract

The invention discloses a final stage control and protection device for a three-phase electric water boiler, comprising a working relay and a protection relay. One end of the electric heating pipe of the water boiler is connected to the zero line of the power supply, and the other end is connected with three wires in parallel, and each wire is provided with There are working relays and protection relays. The protection relay is located on the side close to the electric heating tube. The other side of the protection relay is connected with a working relay. The three phase wire ends are connected, the secondary of the transformer on each live wire is connected to a protection circuit through the winding wire, the three phase wire ends of the three-phase alternating current are connected to a power supply circuit, and the current output terminal of the power supply circuit is connected to the protection circuit. The input end and the current output end of the power supply circuit are also connected with the water boiler microcontroller control board. The protection device of the present invention can reliably protect any one phase line of the input or output of the three-phase protector, and completely prevent the occurrence of accidents.

Description

technical field [0001] The invention relates to a protection device for a water boiler, in particular to a final stage control protection device for a three-phase electric water boiler. Background technique [0002] At present, household and commercial water boilers have become very popular. Most of the control circuits use microcomputer single-chip intelligent control chips in the front stage. This part is relatively mature and stable, while the rear stage uses relays or AC contactors to connect to high-power electric heating tubes. The power of the electric heating tube ranges from two kilowatts to 12 kilowatts, and the working current is large. Once the relay contacts are stuck, the temperature of the water heater will inevitably be out of control. Although the CPU has issued an instruction to stop heating, the stuck relay will make the electric heating tube continue to work. If it is a sealed water tank, there is a danger of explosion. Even if the water tank with a steam...

AI Technical Summary

Problems solved by technology

The power of the electric heating tube ranges from 2kW to 12kW, and the working current is large. Once the contacts of the relay are stuck, the temperature of the water boiler will inevitably lose control. Although the CPU has issued an instruction to stop heating, the stuck relay will allow the electric heating tube to continue to work. If it is a sealed water tank, there is a danger of explosion. Even if the water tank with a steam exhaust pipe does not explode, a large amount of steam will leak out and cause burns.

In addition, through the fault analysis of "spontaneous combustion" commercial water boilers, we found that the main culprit for the "spontaneous combustion" of these water boilers is the aging or poor contact of the connection line between the relay control board and the electric heating tube. Once the circuit is aging or the contact is poor, a strong electric arc and electric spark will be enough to cause the water boiler to ignite spontaneously and cause a fire accident.

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