JPH0241263B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a load selection device suitable for connecting two electrical devices to one electrical outlet and selecting one of the electrical devices.

BACKGROUND ART Conventionally, large-capacity electrical devices such as air conditioners and microwave ovens are usually connected to electrical outlets that are wired with dedicated wiring in a 1:1 correspondence with wiring connections and disconnectors. However, even if you want to use two electrical devices in a room or place such as a condominium where there is only one outlet with dedicated wiring, it is often not possible to easily add more dedicated wiring or outlets, and it is often difficult to use one electrical outlet. For safety reasons, it is not possible to energize two electrical devices at the same time, so the user must alternately insert the plug into a single outlet and operate the device, which is very inconvenient for the user.

Therefore, the present applicant proposed in an earlier application that it is possible to connect two electrical devices to one electrical outlet and select one of the electrical devices by providing a switch for each branch circuit branching from one electrical outlet. has been done.

However, in this proposal, since each branch circuit must be provided with a switch and a current detection means, the cost becomes relatively high.

An object of the present invention is to provide a load selection device that solves the above-mentioned problems and enables cost reduction.

To achieve this objective, the present invention provides that between a main circuit connected to a power supply and first and second branch circuits to which two loads are respectively connected, a common contact is connected to the main circuit and a normally open contact is connected to the main circuit. The double-throw switching section is arranged so that the normally closed contact is connected to the first branch circuit and the normally closed contact is connected to the second branch circuit, and a current detection means for detecting the load current is provided in the main circuit. A high-impedance voltage detection means is connected between the common contact and the normally open contact of the double-throw switching section, and when the current detection means does not detect the load current, the voltage is applied to the double-throw switching section according to the detection output of the voltage detection means. control means for outputting a normally open contact ON signal to the double-throw opening/closing section; The present invention is characterized in that it is equipped with on-state holding means that outputs an on-state, so that one double-throw switching section opens and closes two branch circuits, and one current detection means detects the load current of the load. shall be.

The present invention will be explained in detail below based on illustrated embodiments.

The drawing shows one embodiment of the present invention, in which one of two loads is selected. Two branch circuits 4a and 4b branched from the main circuit 3 are provided between the power supply side terminal 1 and the load side terminals 2a and 2b, and a double-throw switching section 5 is provided between the main circuit 3 and the branch circuits 4a and 4b. is provided. The double-throw switching section 5 includes a normally open contact 6a, a normally closed contact 6b, and a common contact 6c, and also has a contact that turns on between the normally open contact 6a and the common contact 6c by excitation of the relay coil 7. 8. As this double-throw opening/closing part, a switching contact of a relay that is switched by energizing or de-energizing the relay coil 7 is used. Load side terminal 2a,
Loads 9a and 9b are respectively connected to 2b.
When the load 9a or the load 9b is energized, the current flowing through the main circuit 3 is detected by the current transformer 10, respectively. A resistor 11 with an impedance higher than the impedance of the load 9a and a light emitting diode 1 are connected between the common contact 6c and the normally open contact 6a of the double-throw switching section 5.
2 and a photocoupler 14 consisting of a phototransistor 13 are connected in parallel. The output from the photocoupler 14 is input to a monostable multivibrator 16 via a logic converter 15 provided with a delay section.

An amplifier 17, a rectifier 18, and a comparator 19 are connected to the output side of the current transformer 10. Reference voltage generation circuit 20 generates a reference voltage for comparator 19a.
On the output side of the comparator 19, an AND gate 21, D
A flip-flop 22 and a monostable multivibrator 23 are connected. The OR gate 24 outputs a high level when a high level signal is input for a certain period of time from the monostable multivibrator 23, or when a low level signal is input from the initial reset section 25, and resets the D flip-flop 22. The OR gate 26 connects the switching circuit 27 when a high level signal is input to either input terminal.
Outputs a high level signal to.

When a high level signal is input from the OR gate 26, the switching circuit 27 excites the relay coil 7 and turns on the normally open contact 6a, and when a low level signal is input, the relay coil 7 is deenergized and becomes normally closed. Turn on contact 6b.

Next, the operation will be explained. When the relay coil 7 is not energized, the double-throw switching section 5 turns on the normally closed contact 6b and turns off the normally open contact 6a. First, when the load 9a is in the ON state, substantially the power supply voltage is applied between the common contact 6c of the double-throw switching section 5, the resistor 11 connected in parallel between the normally open contact 6a, and the photocoupler 14. Note that the resistor 11 has a considerably higher low resistance value than the impedance of the load 9a (impedance of the load 9a<<resistance 11).

When a power supply voltage is applied, a current flows through the light-emitting diode 12 and it emits light, and the light impinges on the phototransistor 13 and is converted to a logic level by the logic converter 15, which is input to the monostable multivibrator 16. A high-level signal is input from the monostable multivibrator 16 to one input terminal of the AND gate 21, and the other input terminal is not detected by the current transformer 10.
A low level signal is input through the amplifier 17, rectifier 18, and comparator 19, and therefore, the AND gate 2
A high level signal is output from 1. When a high-level signal is input, the switching circuit 27 excites the relay coil 7 and closes the double-throw opening/closing section 5.
The contact 8 switches from the normally closed contact 6b to the normally open contact 6a.

When the normally open contact 6a is turned on, the load 9a is energized and detected by the current transformer 10. This detection signal passes through an amplifier 17 and a rectifier 18 to a comparator 1.
9 outputs a high level signal. Due to the high level signal input, the output of the AND gate 21 becomes low level. The high level signal from the comparator 19 is input to the clock input terminal CK of the D flip-flop 22. At this time, since the high level signal from the monostable multivibrator 16 is input to the input terminal D, the high level signal from the D flip-flop 22 is input to the input terminal D.
The output of the output terminal Q is inverted to high level. Therefore, the output of the output terminal Q of the D flip-flop 22 becomes high level, and the switching circuit 27 continues to excite the relay coil 7 through the OR gate 26, and continues to energize the load 9a. still,
When the load 9a changes from the energized state to the switching state, the output of the comparator 19 is reversed from high level to low level, so that the monostable multivibrator 2
The pulse generated at step 3 is input to the input terminal R of the D flip-flop 22 and is reset, so that the relay coil 7 becomes non-energized.

Next, a case where the load 9b is in the on state will be explained. The double-throw switching section 5 is not switched, and the load 9b is energized, and the current is detected by the current transformer 10. The detection signal passes through an amplifier 17 and a rectifier 18b,
A high level signal from the comparator 19 is input to the AND gate 21, and its output becomes a low level. Furthermore, since a low level signal is input to the input terminal D of the D flip-flop 22, the output from the output terminal Q of the D flip-flop 22 is at a low level. Therefore, the output of the OR gate 26 becomes low level, the switching circuit 27 does not excite the relay coil 7, and the load 9b continues to be energized.

Next, a case where the loads 9a and 9b are in the on state at the same time will be explained. Since the relay coil 7 is not excited, the double-throw switching section 5 turns on the normally closed contact 6b, so that the load 9b is energized and the current is detected by the current transformer 10. In response to the detection signal, a high level signal is output from the comparator 19 via the amplifier 17 and the rectifier 18, and is input to the AND gate 21 and the D flip-flop 22, respectively. Due to the high level signal input, the output of the AND gate 21 becomes low level. , On the other hand, the photocoupler 14 operates due to the ON state of the load 9a,
The logic converter 15 includes a phototransistor 13.
However, since the logic converter 15 includes a delay section, the output of the logic converter 15 is delayed by a predetermined time. Therefore, at the time when the output of the comparator 19 is inverted to high level, the output of the monostable multivibrator 16 is still at low level, and the output terminal Q of the D flip-flop 22 is
The output of is held low. Therefore, the output of the OR gate 26 becomes a low level, the switching circuit 27 does not excite the relay coil 7, the normally closed contact 6b continues to be turned on, and the load 9b is energized preferentially.

According to this embodiment, the circuit can be configured by using one double-throw switching section 5 and one current transformer 10, so that cost reduction can be achieved.

In the illustrated embodiment, the current transformer 10 corresponds to current detection means, the resistor 11 and photocoupler 14 correspond to voltage detection means, the AND gate 21 and the monostable multivibrator 16 correspond to control means, and D
The flip-flop 22 and the monostable multivibrator 16 correspond to on-state maintaining means.

In this embodiment, a current transformer 1 is used to detect the current.
0 was used, but it is not limited to this, and a flow divider may also be used.
Also, a transformer may be used instead of the resistor and photocoupler. Note that the DC power supply section is omitted.

As explained above, according to the present invention, between the main circuit connected to the power supply and the first and second branch circuits to which two loads are respectively connected, a common contact is connected to the main circuit, and a normally open contact is connected to the main circuit. The double-throw switching section is arranged so that the normally closed contact is connected to the first branch circuit and the normally closed contact is connected to the second branch circuit, and a current detection means for detecting the load current is provided in the main circuit. A high-impedance voltage detection means is connected between the common contact and the normally open contact of the double-throw switching section, and when the current detection means does not detect the load current, the voltage is applied to the double-throw switching section according to the detection output of the voltage detection means. control means for outputting a normally open contact ON signal to the double-throw opening/closing section; The present invention is equipped with on-state holding means that outputs , so that one double-throw switching section opens and closes two branch circuits, and one current detection means detects the load currents of two loads. , as in the previous application, the circuit configuration is such that the cost is reduced compared to that in which two branch circuits are opened and closed by two switching parts and the load currents of two loads are detected by two current detection means. be able to.

[Brief explanation of the drawing]

The drawing is a circuit diagram showing an embodiment of the present invention. 1...Power supply side terminal, 3...Main circuit, 5...Double throw switching section, 7...Relay coil, 10...Current transformer,
11...Resistor, 14...Photocoupler, 21...
AND gate, 22...D-flipflop,
27...Switching circuit.

Claims (1)

[Claims] 1. Between a main circuit connected to a power source and first and second branch circuits to which two loads are respectively connected, a common contact is connected to the main circuit, and a normally open contact is connected to the first branch circuit. A double-throw switching section is arranged in the circuit so that the normally closed contact is connected to the second branch circuit, and a current detection means for detecting the load current is provided in the main circuit, and the common contact of the double-throw switching section and A high impedance voltage detection means is connected between the normally open contact and the current detection means does not detect the load current.
The control means is provided with a control means for outputting a normally open contact ON signal to the double-throw opening/closing part in response to the detection output of the voltage detection means, and further in response to the detection output of the current detection means subsequent to the detection output of the voltage detection means. A load selection device comprising on-state holding means for outputting an on-signal of a normally open contact to a double-throw opening/closing part.