JPH10172720A - Heater short-water heating preventive mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily judge whether cutoff of a power source is caused by short- water heating of a heater or by the other apparatus by arranging a temperature sensing means, a relay means actuated by it and a means to display short-water heating by reclosing of a switch of an earth leakage breaker. SOLUTION: When an electric heater 3 is put in a shorwater heating condition, a surface temperature of the heater 3 rises, and a temperature fuse 11 is fused, and an exciting coil 25 of a relay means operates, and closes a contact point 15a. Therefore, an electric current exceeding a sensing current of an earth leakage breaker 9 flows to a fixed resistor 27, and the breaker 9 operates since a balance of an electric current passing through the inside of its coil is lost. Therefore, since a lamp 21 connected in parallel to the temperature fuse 11 is lighted when a switch 17 of the breaker 9 is closed again, the fact that the breaker 9 operates by short-water heating of the heater 3 can be known. In the case where it is operated by a power source of the other apparatus, when the switch 17 is closed again, the lamp 21 is not lighted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mechanism for preventing heating of an electric heater using an earth leakage breaker used to prevent damage to equipment, water leakage, etc. due to electric heating of an electric heater.

[0002]

2. Description of the Related Art Conventionally, an electric water heater 5 as shown in FIG. The electric water heater 5 includes a tank 1 for storing water, and an electric heater 3 which is charged into the tank 1 so as to heat the water in the tank 1.

[0003] Such an electric water heater 5 is provided with a shutoff system for shutting off the power supply to the electric heater 3 by an earth leakage breaker 9 for shutting off the power supply 7. That is, the shut-off system detects the change in the abnormal current when the electric heater 3 is in the state of idling, and the earth leakage breaker 9 detects the power supply 7 to the electric heater 3.
Is interrupted by the switch 17 of the earth leakage breaker 9.

[0004]

However, since the earth leakage breaker 9 is designed to shut off even when other equipment in the home is abnormal, when the power supply is cut off by the earth leakage breaker 9, the electric heater 3 is turned off. There is a problem that it is not possible to determine whether the cutoff is caused by the empty cooking or the cutoff by another device.

[0005] Therefore, an object of the present invention is to easily determine whether the power supply is cut off by an electric heater when the power supply is cut off by an earth leakage breaker or by another device. An object of the present invention is to provide a mechanism for preventing an electric water heater from being overheated.

Another object of the present invention is a mechanism for preventing a heater from being cooked by using an earth leakage breaker to prevent damage to equipment and water leakage due to the heater being cooked. Another object of the present invention is to provide a heater emptying prevention mechanism capable of preventing water leakage and the like.

[0007]

According to the present invention, there is provided an electric heater for heating a liquid, and an abnormality when the electric heater is in a baking state is sensed by a change in current to supply electric power to the electric heater. A heater for preventing overheating of the heater, comprising: an electric leakage breaker for interrupting supply; a temperature sensing means for sensing an increase in the temperature of the electric heater when the electric heater is in an idling state; and a temperature of the temperature sensing means. Relay means which operates by sensing, and display means for displaying that the earth leakage breaker has been cut off by the idling of the electric heater by turning on the switch of the earth leakage breaker again when the relay means has been operated. Thus, a mechanism for preventing the heater from being overheated is provided.

According to the present invention, the relay means includes an exciting coil connected in parallel with the electric heater and at both ends of the electric heater in series with the temperature sensing means, and a relay between the earth leakage breaker and the electric heater. A relay contact connected to one power supply line and the other power supply line between the earth leakage breaker and the power supply, and a specific resistance connected between the relay contact and the one power supply line. The current of the earth leakage breaker is maintained and the earth leakage breaker does not operate, and when the electric heater becomes empty, the relay contact is closed by a rise in the surface temperature of the electric heater. A cooking prevention mechanism is obtained.

[0009]

The power supply to the electric heater is safely shut off by using the thermal fuse and the earth leakage breaker. The test circuit of the earth leakage breaker is not operated and the earth leakage is not intentionally caused. The display means determines whether the earth leakage breaker has operated due to the earth leakage or the circuit of another device.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a mechanism for preventing a heater from being overheated according to the present invention.

Referring to FIG. 1, an electric water heater 5 for supplying hot water includes a tank 1 for storing water, and an electric heater 3 inserted into the tank 1 so as to heat the water in the tank 1.

The mechanism for preventing the electric water heater 5 from being cooked by the heater is to cut off the power supply to the electric heater 3 by the earth leakage breaker 9 that cuts off the power supply 7 when the electric heater 3 is in the idling state. And an earth leakage breaker 9 for interrupting the supply of the power source 7 to the electric heater 3 by sensing the change in the abnormal current.

[0013] The heater overheating prevention mechanism includes a temperature sensing means for sensing a rise in the temperature of the electric heater 3 when the electric heater 3 is in the baking state, a relay means operated by the temperature sensing of the temperature sensing means, and a relay means. The switch 17 of the earth leakage breaker 9 is turned on again when is operated, and a display means 21 is provided to indicate that the earth leakage breaker 9 has been cut off by the burning of the electric heater 3. The relay means operates the earth leakage breaker 9 from an external circuit without improving the earth leakage breaker 9.

More specifically, the relay means of the heater emptying prevention mechanism is provided in parallel with the electric heater 3 and at both ends of the electric heater 3 a temperature fuse 11 serving as a temperature sensing means.
An exciting coil 25 connected in series with the relay contact 15a connected to one power supply line A between the earth leakage breaker 9 and the electric heater 3 and another power supply line B between the earth leakage breaker 9 and the power supply 7; It has a relay contact 15a and a specific resistance 27 connected between the one power supply line A.

When the electric heater 3 is in a normal state,
Since no current flows through the circuit between the specific resistance 27 and the relay contact 15a, the current of the earth leakage breaker 9 is maintained, so that the earth leakage breaker 9 does not operate. The electric heater 3
Is in the state of being cooked, the temperature fuse 11 is blown by the rise of the surface temperature of the electric heater 3, and the exciting coil 25 of the relay means operates to close the relay contact 15a. Since a fixed resistor of 10 kΩ is attached to the circuit in which the relay contact 15a is closed, a 20 mA
Current flows. Since the sensing current of the earth leakage breaker 9 is 15 mA, the current flowing through the coil of the earth leakage breaker 9 is out of balance, so that the earth leakage breaker 9 operates.

As described above, in the mechanism for preventing the electric water heater from being overheated, the display means 21 connected in parallel with the temperature fuse 11 is turned on when the switch 17 of the earth leakage breaker 9 is turned on again. It can be seen that the earth leakage breaker 9 has been operated by the empty cooking.

In the operation at the time of electric leakage, the supply of the power supply 7 is cut off as a normal electric leakage breaker 9. That is, when the earth leakage breaker 9 operates due to earth leakage of another device on the load side,
When the switch 17 of the earth leakage breaker 9 is turned on again, the lamp as the display means 21 does not turn on, so that it is understood that the earth leakage breaker 9 has been operated due to earth leakage by another device.

As the temperature sensing means for sensing the temperature of the electric heater 3, a PCT thermistor which senses a rise in temperature and changes in resistance may be used in place of the temperature fuse 11.

[0019]

As described above with reference to the embodiment, according to the heater emptying prevention mechanism of the present invention, the temperature sensing means for sensing an increase in the temperature of the electric heater when the electric heater is in the idling state. And display means for indicating that the leakage breaker has been interrupted by the burnout of the electric heater by turning on the leakage breaker again when the relay means has been activated. When the supply is cut off, it is possible to easily determine whether the cutoff is caused by the empty heating of the electric heater or by another device.

In addition, an earth leakage breaker can be used to prevent damage to equipment and water leakage due to empty heating of the heater, and also to prevent damage to a liquid storage tank and water leakage.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of a mechanism for preventing an empty heater from being heated according to the present invention.

FIG. 2 is a circuit diagram showing a circuit configuration of a conventional electric water heater and a heater earth leakage breaker.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Tank 3 Electric heater 5 Electric water heater 7 Power supply 9 Leakage breaker 11 Thermal fuse 15a Relay contact 17 Switch 21 Display means 25 Excitation coil 27 Specific resistance

Claims (2)

[Claims] 1. An electric heater for heating a liquid, and an earth leakage circuit breaker for sensing an abnormality when the electric heater is in an idle state by a change in current and interrupting supply of power to the electric heater. A temperature sensing means for sensing a rise in the temperature of the electric heater when the electric heater is in a baking state, a relay means operating by sensing the temperature of the temperature sensing means, and the relay means. And a display means for displaying that the electric leakage breaker has been cut off by the burning of the electric heater by turning on the switch of the electric leakage breaker again when the power supply has been operated. Cooking prevention mechanism. 2. The heater emptying prevention mechanism according to claim 1, wherein said relay means is connected to said electric heater in parallel and at both ends of said electric heater in series with said temperature sensing means, and said leakage cutoff. A relay contact connected to one power line between the power supply and the electric heater and the other power line between the earth leakage breaker and the power supply, and a specific resistance connected between the relay contact and the one power line. When normal, the current of the earth leakage breaker is kept in balance and the earth leakage breaker does not operate, and when the electric heater is empty, the relay contact is closed by a rise in the surface temperature of the electric heater. A heater empty cooking prevention mechanism characterized by the above-mentioned.