JP2002300738A - Lamp load control device for single-phase three-wire type cable run - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device capable of controlling a passing current without blocking a controlled circuit as much as possible in the case that a current of a cable run exceeds a prescribed current value. SOLUTION: The device comprises: two current transformers A that detect passing currents having L1, L2 phases of the monitored cable run, respectively; a current transformer B that detects a passing current of the controlled circuit; a current- measuring circuit 3 that receives a signal from the current transformers AB and measures a passing current of each transformer; a current-setting circuit 4 that sets the upper limit of the passing current of the monitored cable run (hereinafter called as a set current value); a comparison arithmetic circuit 5 that performs a comparison operation of the passing current obtained by the current measuring circuit 3 and the set current value obtained by the current setting circuit 4; a load-control circuit 6 that receives a signal from the comparison arithmetic circuit 5 and controls a changeover means; the changeover means 7 that switches the connection of the controlled circuit to either an L1 side or an L2 side, or to blocking; a recovery-current setting circuit 8 that sets a recovery current that recovers the controlled circuit when the passing current of the monitored cable run is maintained below the prescribed current value for a certain time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling a current flowing through a monitoring circuit to less than a set current value, and a main circuit breaker when a current value flowing through the monitoring circuit exceeds the set current value. The present invention belongs to a technique for controlling the energized state of a control target circuit before the operation of the circuit, thereby preventing the entire circuit from going into a power failure state.

[0002]

2. Description of the Related Art There are the following devices for controlling the current flowing through a monitoring circuit to a value less than a set current value. FIG.
1 shows a block diagram of a conventional apparatus. The value of the current flowing in the monitoring circuit is input from the current transformer to the current measurement circuit, and the current value of the circuit is set by comparing the current value with the set current value determined by the current setting circuit by the comparison circuit. When the current value is exceeded, a predetermined control target circuit is automatically turned off by a current control circuit, thereby preventing a main circuit breaker from operating and causing a power outage of the entire circuit. . Further, when the return current setting circuit allows a sufficient amount of current to flow through the monitoring circuit with respect to the set current value, the circuit to be controlled, which has been cut off by the current control circuit, is turned on and returned.

[0003]

In the above-described conventional device for controlling the current supplied to the monitoring circuit to be less than the set current value, the L1 phase and the L2 phase in the circuit have not been distinguished. Therefore, the balance of the current flowing in both phases is lost due to the use condition of the load, and even if only one phase exceeds the set current value and the other phase has room for the set current value, In some cases, the circuit was shut down and the circuit could no longer be used. The present invention relates to a device for controlling the current flowing through a monitoring circuit to be less than a set current value, by measuring the currents of both phases of the circuit respectively to control as much as possible when the current of the circuit exceeds the set current value. It is an object of the present invention to provide a device capable of controlling a conduction current by switching a circuit to a phase having a sufficient current without interrupting a target circuit.

[0004]

Means for Solving the Problems Two current transformers A for detecting the currents flowing through the L1 and L2 phases of the monitoring circuit, current transformers B for detecting the currents flowing through the circuit to be controlled, and the current transformers AB And a current measuring circuit that measures the current flowing through each of the current transformers, a current setting circuit that sets the upper limit of the current flowing through the monitoring circuit (hereinafter referred to as a set current value), and a current measuring circuit. A comparison operation circuit that performs a comparison operation of the supplied current value and the set current value obtained by the current setting circuit, a load control circuit that receives a signal from the comparison operation circuit, and controls a switching unit;
Switching means for switching the connection of the control target circuit to one of the L1 side, L2 side, and disconnection state, and a return current for returning the control target circuit when the current flowing through the monitoring circuit continues to be a predetermined current value or less for a certain period of time. And a return current setting circuit for setting the current, when the current flowing in either the L1 phase or the L2 phase of the electric circuit exceeds the set current value by the comparison operation circuit, the switching is performed by the judgment of the comparison operation circuit. The means is configured to switch the connection of the control target circuit to a phase side having a sufficient current flow, or to switch the control target circuit to a cut-off state when the current flow of both phases does not have a margin with respect to a set current value. .

[0005]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an apparatus for controlling the current flowing through a monitoring circuit to less than a set current value according to the present invention. The target electric circuit is a single-phase three-wire electric circuit, and two current transformers A indicated by 1 in each phase of L1 and L2, a current transformer B indicated by 2 in the electric circuit of the control target circuit, and a current measuring circuit 3 A current setting circuit 4, a comparison operation circuit 5, a load control circuit 6,
It comprises a switching means 7 for the circuit to be controlled and a return current setting circuit 8. The first current transformer A detects a current flowing through the monitoring circuit 9 and outputs a signal of the magnitude. In the present invention, a single-phase three-wire electric circuit is assumed. In this case, two electric circuits are provided to detect the current amounts of the L1 phase and the L2 phase at both ends. The second current transformer B detects a current flowing through the control target circuit provided on the monitoring circuit and outputs a signal. The control target circuit is provided as a load of the monitoring circuit. Here, a plurality of control target circuits may be provided as appropriate according to the number of circuits to be controlled. The current measuring circuit 3 includes two current transformers A shown in 1 and current transformers B shown in 2
And a circuit for measuring the current flowing through the monitoring circuits L1 and L2 and the circuit to be controlled. Current setting circuit 4
Is a circuit for setting the upper limit of the energizing current in the monitoring circuit. Generally, the current is set to a value at which the main circuit breaker provided in the monitoring circuit is difficult to operate. The comparison operation circuit 5 performs a comparison operation on the current signals from the current measurement circuit 3 and the current setting circuit 4 and, if the current flowing through the L1 or L2 monitoring circuit exceeds the current set value, a control target circuit according to the situation. The switching signal is output to the load control circuit 6. Further, after the control target circuit is turned off,
The current value of the 1-phase or the L2-phase is compared with the current value set by the return current setting circuit 8, and if the state where the supplied current is less than the return current value is continued, a signal is output to the load control circuit 6, The control target circuit is reconnected to L1 or L2 of the monitoring circuit 9. The load control circuit 6 receives the control target circuit switching signal from the comparison operation circuit 5 and controls the switching means according to the signal. The control target circuit switching means 7 receives a signal from the load control circuit 6 and switches the connection of the control target circuit from the currently connected phase to another phase,
It is to be in a cutoff state. In the present embodiment, a switch is used to connect the L1 phase control target circuit,
Connection switching between three states, that is, connection of the control target circuit of the phase and complete disconnection is enabled.

The return current setting circuit 8 sets the return current value such that the current flowing through the monitoring circuit becomes less than the set current value when the control target circuit in the “OFF” control state is restored by the load control circuit. Set. For example, if the return current value is a value obtained by subtracting the energization current value of the control target circuit obtained by the current transformer B shown in 2 from the set current value, the energization current of the monitoring circuit even if the control target circuit returns. Obtains a return current value that does not exceed the current set value.

Here, the principle of the present invention will be described.
This will be described with reference to FIGS.

FIG. 2 shows the instantaneous flow of current depending on the use state of a load in a single-phase three-wire monitoring circuit. Reference numeral 10 denotes a main circuit breaker; 201, an L1 load indicating the entire load connected to the L1 phase; and 202, an L2 load indicating the entire load connected to the L2 phase. I have. The voltage between the L1 phase and the N phase and the voltage between the L2 phase and the N phase are each 100 V, and the voltage between L1 and L2 is 200 V. The phases of the currents flowing through the L1 and L2 phases are substantially the same. Assuming that the respective phases are balanced and the resistances of the L1 side load 12 and the L2 side load 13 are respectively 10Ω and the same, the current of the L1 side is 10A,
The current on the L2 side is 10 A, which is the same. Here, the current is canceled and does not flow through the N phase. Also, of the overcurrent elements provided at each pole of the main circuit breaker 10,
The same current flows through the elements corresponding to the L1 phase and the L2 phase.

FIG. 3 shows a case where there is a difference between the resistance values of the L1 load 12 and the L2 load 13 shown in FIG. Here, the L1 side load 201 is 4
The case where the Ω, L3 side load 202 is 10Ω is shown.
In this case, 25A flows to the L1 side, 10A flows to the L2 side, and 15A which is a difference obtained by subtracting 10A from 25A flows to the N phase. When the rated current of the main circuit breaker 11 is 20 A, the current on the L1 side exceeds the rating, so that the main circuit breaker 10 operates after a predetermined time. However, since the current on the L2 side is 10 A, there is a margin of 50% with respect to the rated current. In such a case, among the loads connected to the L1 side, a specific load is switched to the L2 side by the switching means, so that the current flowing through the loads between the respective phases is balanced and the main circuit breaker 10 is switched.
The current flowing through each overcurrent element can be balanced.
It is possible to control the current flowing through the monitoring circuit within the rated current of the main circuit breaker 10.

According to the present invention, the control is performed based on the principle described above. In the monitoring circuit 9 shown in FIG. 1, two current transformers 1 are used to detect the currents flowing in the L1 and L2 phases. A is connected to both primary and secondary poles of the main circuit breaker 11, and the output from the current transformer A shown in 1 is input to the current measuring circuit 3. Further, a current transformer B2 is provided between the switching means 7 and the control target circuit to measure the current flowing through the control target circuit, and an output signal thereof is input to the current measurement circuit 3. Each of the measured current values is input to the comparison operation circuit 5. The comparison operation circuit 5 is a current measurement circuit 3
, The input from the current setting circuit 4, and the input from the return current setting circuit 8, the current value of the L1 phase, the current value of the L2 phase, the current value of the control target circuit, the set current value, the return current By comparing the values, the phase switching is determined and the cutoff control is determined. When there are a plurality of control target circuits, a control target circuit to be controlled is determined. The cutoff control is performed when only the phase switching exceeds the set current value. Further, when the cutoff control is performed, a signal is sent to the load control circuit 6 when the current value of the monitoring circuit continues to be less than the return current value according to the return current value determined by the return current setting circuit 8; A signal is sent from the load control circuit 6 to the corresponding switching means 7 to restore the control target circuit.

FIG. 4 is a flowchart of an apparatus for controlling the current supplied to the monitoring circuit to less than a set current value according to the present invention. 5 shows an operation program of the comparison operation circuit 5, the load control circuit 6, and the return current setting circuit 8. Numeral 11 denotes a step of reading a current value supplied from the current measuring circuit 3 and a current value set from the current setting circuit 4. Specifically, the current value of the L1 phase, the current value of the L2 phase, and the current value of the control target circuit are read. 12 is a step of judging whether or not the energizing current of the monitoring circuit has reached a set current value. 13 is outputting a predetermined process so that the energizing current of the monitoring circuit becomes less than the set current value according to the amount of energizing current that has exceeded. It is a step to do. Specifically, it is determined whether control for phase switching or control for cutoff is performed. Here, the operator is referred to as "operator MAX (a, b) =
Definition is made by selecting the larger of a and b, operator M
IN (a, b) = defined to select the smaller one of a and b ”, ｛MAX (L1 current value, L2 current value) −set current value｝ <current value of control target circuit and Ｍ MIN (L1 current value, L2 current value) + current value of control target circuit｝ <set current value If the condition is satisfied, phase switching control is performed. If not, cutoff control is performed. Step 14 is a step of receiving a signal from 13 and outputting a signal for switching the phase of the circuit to be controlled. Reference numeral 15 denotes a step of receiving a signal from 13 and outputting a cutoff signal for cutting off a circuit to be controlled. 16 is based on the measured current flowing through the control target circuit.
This is the step of setting the return current. 17 is a step for judging whether or not the energizing current value of the monitoring circuit is lower than the return current value, and 18 is a step for outputting a return of the interrupted control target circuit. Step 1
If it is determined to be "NO" in steps 2 and 17, the processing is repeated through the route indicated by the arrow "NO" until the condition is satisfied.

[0013]

According to the present invention, in a device for controlling the conduction current of a monitoring circuit to be less than a set current value, by measuring the currents of both phases of the circuit, the current of the circuit becomes larger than the set current value. In this case, it is possible to obtain a device capable of controlling a phase current by switching a circuit to a phase having a sufficient current without interrupting a circuit to be controlled as much as possible, thereby controlling a conduction current.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a current flow according to a use state of a load in an electric circuit;

FIG. 3 is a diagram showing a case where there is a difference between resistance values of loads of both phases in an electric circuit;

FIG. 4 is a flowchart of the apparatus.

FIG. 5 is a block diagram of a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Current transformer A 2 Current transformer B 3 Current measuring circuit 4 Current setting circuit 5 Comparison operation circuit 6 Load control circuit 7 Switching means 8 Return current setting circuit 9 Monitoring circuit 10 Main circuit breaker 201 L1 side load 202 L2 side load

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5G064 AA04 AC06 AC09 CB08 CB11 DA05 5G066 GA01 KA01 KA11 KD01 KD10 5H410 BB05 CC03 DD03 DD05 EA28 EB38 FF05 FF25 HH00 LL06 LL15 LL20

Claims (1)

[Claims] 1. A current transformer A for detecting currents flowing through the L1 and L2 phases of the monitoring circuit, a current transformer B for detecting currents flowing through a circuit to be controlled, and a signal from the current transformer AB. And a current measuring circuit for measuring the current flowing through each current transformer, a current setting circuit for setting an upper limit (hereinafter referred to as a set current value) of the current flowing through the monitoring circuit, and a current flowing value obtained by the current measuring circuit. A comparison operation circuit that compares and calculates a set current value obtained by the current setting circuit, a load control circuit that receives a signal from the comparison operation circuit and controls the switching unit, and connects the control target circuit to the L1 side. Switching means for switching to either the L2 side or the cutoff state; and a return current setting circuit for setting a return current such that the control target circuit returns when the current supplied to the monitoring circuit continues to be equal to or less than a predetermined current value for a certain period of time. And the comparison operation circuit If the energizing current of either the L1 phase or the L2 phase of the road exceeds the set current value, the switching means switches the connection of the circuit to be controlled to the phase having more energizing current according to the judgment of the comparison operation circuit. An electric load limiter for a single-phase three-wire circuit, wherein the control target circuit is switched to a cut-off state when switching or when there is no allowance for a set current value in both phases.