JP5986525B2 - Power circuit monitoring system - Google Patents

Description

  The present invention relates to a power supply circuit monitoring system that monitors a power supply state from the three-phase power supply circuit of an auxiliary machine that is fed from a three-phase power supply circuit via the thermal relay of an auxiliary machine circuit having a thermal relay.

  In the auxiliary equipment (for example, auxiliary equipment provided in a generator such as an electric motor such as a motor or a cooling water pump) fed from a three-phase power supply circuit (for example, the system when performing grid connection) There are inconveniences.

  FIG. 4 is a circuit diagram showing an example of a power supply connection circuit 200 in which the auxiliary machine 30 is connected via the auxiliary machine circuit 20 to the three-phase power supply circuit 10 to which the loads Lrs, Lst, and Ltr are connected.

  In the power supply connection circuit 200 shown in FIG. 4, the three-phase power supply circuit 10 is a three-phase three-wire commercial power supply that outputs a voltage of 200 V AC here. In the power supply connection circuit 200 shown in FIG. 4, wiring breakers CB (main circuit breakers) are provided upstream of the loads Lrs, Lst, Ltr and the auxiliary circuit 20. Here, the auxiliary machine 30 is an auxiliary machine provided in a generator (for example, an engine generator) such as an electric motor such as a motor or a cooling water pump.

  In the power supply connection circuit 200, an open phase occurs in the three phases of the R phase, the S phase, and the T phase in the three phase power supply circuit 10, or the R phase-S phase, the S phase-T phase, The power Prs, Psr, Ptr consumed between the three phases of the R phase, the S phase, and the T phase becomes non-uniform depending on the usage state of the loads Lrs, Lst, Ltr connected between the T phase and the R phase. The interphase voltages Vrs, Vst, Vtr between the three phases of the phase and the T phase may become unbalanced. Then, an overcurrent flows from the three-phase power supply circuit 10 to the auxiliary machine 30, which causes the auxiliary machine 30 to overheat and cause the auxiliary machine 30 to burn out.

  In order to prevent such an overcurrent to the auxiliary machine 30, a thermal relay 21 is provided in the auxiliary machine circuit 20, which allows the electric circuit to be cut off (tripped) and restored when a current exceeding a predetermined value flows in the auxiliary machine circuit 20. Conventionally known is a configuration in which when the current exceeding a predetermined value flows and the thermal relay 21 generates heat, the power supply to the auxiliary machine 30 of the three-phase power supply circuit 10 is interrupted by the interruption of the electric circuit by the thermal relay 21.

  Specifically, the auxiliary circuit 20 includes a thermal relay 21 and an electromagnetic contactor 22. The thermal relay 21 is provided in an electric circuit (in this example, R phase, T phase) connected to the auxiliary machine 30 of the auxiliary machine circuit 20 in order to protect overheating of the auxiliary machine 30 due to overcurrent. The thermal relay 21 is also called a thermal relay, and operates the electromagnetic contactor 22 by generating heat by a current exceeding a predetermined value so that the current flowing through the auxiliary machine 30 does not exceed the allowable upper limit value. The magnetic contactor 22 interrupts power supply from the three-phase power supply circuit 10 to the auxiliary machine 30 by the operation of the thermal relay 21. That is, the auxiliary machine circuit 20 is used as an electromagnetic switch using the thermal relay 21 and the electromagnetic contactor 22.

  Specifically, the thermal relay 21 is provided between the two heat-generating parts 21r and 21t provided in the electric circuit (R phase and T phase in this example) connected to the auxiliary machine 30 of the auxiliary circuit 20 and between the two phases (this example). , The contact portion 21a is provided on the electric circuit L1 connected between the R phase and the S phase. In the thermal relay 21, the contact parts 21 a are turned on when the heat-acting parts 21 r and 21 t are not in operation, and the heat-acting parts 21 r and 21 t are activated by the heat generated by the current exceeding the predetermined value. In this way, it is turned off. The thermal motion parts 21r and 21t include a bimetallic thermal element and a heat element that generates heat by a current exceeding a predetermined value and heats the thermal element. A conventionally known thermal relay 21 can be used as the thermal relay 21, and detailed description thereof is omitted here.

  The electromagnetic contactor 22 includes an electromagnetic coil 22a provided in the electric circuit L1 and first contact portions 22r provided in each of the R phase, S phase, and T phase connected to the auxiliary machine 30 of the auxiliary circuit 20. 22s and 22t, and a second contact portion 22b provided in the electric circuit L2 connected in parallel to the first push button switch 23 described later with respect to the electric circuit L1. In the magnetic contactor 22, when the first push button switch 23 is in an off state and the electromagnetic coil 22a is not activated, the first contact portions 22r, 22s, 22t and the second contact portion 22b are in an off state, and the first contact state is in the off state. The contact portions 22r, 22s, 22t and the second contact portion 22b are turned on when the electromagnetic coil 22a is actuated by energization by the first push button switch 23.

  The auxiliary circuit 20 further includes a first push button switch 23 and a second push button switch 24 provided in the electric circuit L1 in addition to the thermal relay 21 and the electromagnetic contactor 22. The first push button switch 23 has a contact point that is closed by a pressing operation and returns to an open circuit when the pressing operation is released. The second push button switch 24 has a contact point that is opened by a pressing operation and returns to a closed state when the pressing operation is released.

  In the power supply connection circuit 200 described above, when the first push button switch 23 is pressed, a current flows through the electromagnetic coil 22a, the first contact portions 22r, 22s, 22t and the second contact portion 22b are closed, and the auxiliary machine 30 is supplied with power from the three-phase power supply circuit 10 through the first contact portions 22r, 22s, and 22t. At this time, even if the pressing operation of the first push button switch 23 is released, the second contact portion 22b performs the self-holding operation. Thereby, the ON state of the first contact portions 22r, 22s, 22t and the second contact portion 22b is maintained, and the power supply from the three-phase power supply circuit 10 to the auxiliary machine 30 is maintained. On the other hand, when the second pushbutton switch 24 is pressed, the energization of the electromagnetic coil 22a is released, the self-holding operation by the second contact portion 22b is released, and the first contact portions 22r, 22s, 22t and the second When the contact portion 22b is turned off, power supply from the three-phase power supply circuit 10 to the auxiliary machine 30 is stopped.

  When the auxiliary machine 30 is supplied with power from the three-phase power supply circuit 10 and a current exceeding a predetermined value flows through the thermal relay 21, the contact portion 21a in the on state of the thermal relay 21 is replaced with the thermal units 21r and 21t. Is turned off by the heat generation operation, and the energization of the electromagnetic coil 22a is released and the first contact portions 22r, 22s, 22t and the second contact portion 22b are turned off. The power supply to is cut off.

  By the way, in the structure which interrupts the electric power feeding to the auxiliary machine 30 of the three-phase power supply circuit 10 by the thermal relay 21, as a factor which interrupts the electric power feeding to the auxiliary machine 30 of the three-phase power supply circuit 10, R in the three-phase power supply circuit 10 A phase failure occurs in the three phases of the phase, S phase, and T phase, or the interphase voltages Vrs, Vst, Vtr between the three phases of the three-phase power supply circuit 10 become unbalanced, and the thermal relay 21 exceeds a predetermined value. In addition to the case where current flows, the thermal relay 21 itself may malfunction.

  Therefore, it was not possible to identify whether the factor that interrupted the power supply to the auxiliary machine 30 of the three-phase power circuit 10 was the factor on the three-phase power circuit 10 side or the factor on the thermal relay 21 side. .

  In this regard, in Patent Document 1, in order to accurately detect disconnection and short-circuit of the current transformer, the current of the secondary circuit of the current transformer is obtained and the received power or the received current from the commercial power source is less than a predetermined value. A configuration for detecting that this state has continued for a predetermined time or more is disclosed.

Japanese Patent No. 3908203 (Japanese Patent Laid-Open No. 2005-45859)

  However, even if the configuration described in Patent Document 1 is used, the reason why the power supply to the auxiliary equipment of the three-phase power circuit is interrupted is the factor on the three-phase power circuit side or the thermal relay side. Cannot identify the cause.

  Therefore, the present invention provides a power supply that can identify whether the factor that interrupts the power supply to the auxiliary equipment of the three-phase power supply circuit is a factor on the three-phase power supply circuit side or a factor on the thermal relay side. An object is to provide a circuit monitoring system.

In order to solve the above-mentioned problem, the present invention provides a power supply for monitoring the power supply state from the three-phase power supply circuit of an auxiliary machine that is fed from the three-phase power supply circuit via the thermal relay of the auxiliary circuit having a thermal relay. a circuit monitoring system, detection means for detecting the phase voltage among the three phases of the three-phase power supply circuit, provided a recording control means for recording the inter-phase voltage detected by said detecting means, said recording control means Monitoring the recorded interphase voltage, and when the power supply to the auxiliary machine of the three-phase power supply circuit is cut off, the factor that cuts off the power supply to the auxiliary machine of the three-phase power supply circuit is the three-phase power supply Provided is a power supply circuit monitoring system for identifying whether the factor is on the circuit side or the factor on the thermal relay side .

According to the present invention, the detecting means for detecting the interphase voltage between the three phases of the three-phase power supply circuit and the recording control means for recording the interphase voltage detected by the detecting means are provided , and the recording control means Monitoring the recorded interphase voltage, and when the power supply to the auxiliary machine of the three-phase power supply circuit is cut off, the factor that cuts off the power supply to the auxiliary machine of the three-phase power supply circuit is the three-phase power supply whether factor in circuit side, or in Rukoto identifies whether the factors in the thermal relay side, factors blocking the power supply to the auxiliary machine of the three-phase power supply circuit, in the three-phase power supply circuit side It is possible to identify whether it is a factor on the thermal relay side.

It is a system block diagram which shows schematic structure of an example of the power supply circuit monitoring system applied to the power supply connection circuit shown in FIG. FIG. 2 is a system block diagram mainly showing a second control device in the control unit shown in FIG. 1. It is a flowchart which shows an example of control operation by the 2nd control apparatus of the control part in a power supply circuit monitoring system. It is a circuit diagram which shows an example of the power supply connection circuit with which the auxiliary machine is connected via the auxiliary machine circuit with respect to the three-phase power supply circuit which connected the load.

  Embodiments according to the present invention will be described below with reference to the drawings.

  FIG. 1 is a system block diagram showing a schematic configuration of an example of a power supply circuit monitoring system 100 applied to the power supply connection circuit 200 shown in FIG.

  The connection configuration of the three-phase power supply circuit 10, the auxiliary circuit 20, the auxiliary device 30 and the loads Lrs, Lst, and Ltr and the circuit configuration of the auxiliary circuit 20 in the power supply connection circuit 200 are as described above. Here, the description is omitted, and the power supply circuit monitoring system 100 according to the embodiment of the present invention will be mainly described.

  A power supply circuit monitoring system 100 illustrated in FIG. 1 includes a voltage sensor 110 (an example of a detection unit) and a control unit 120.

  The voltage sensor 110 detects and outputs interphase voltages Vrs, Vst, and Vtr between the R phase and S phase, between the S phase and T phase, and between the T phase and R phase of the three-phase power supply circuit 10. The voltage sensor 110 may be a plurality of voltage sensors that individually detect and output the three-phase interphase voltages Vrs, Vst, and Vtr between the R-phase, S-phase, and T-phase of the three-phase power supply circuit 10. In this case, a single electric energy sensor (OM50 KM50-C) is used. This electric energy sensor not only detects and outputs electric power, but can also detect and output interphase voltages Vrs, Vst, and Vtr among three phases of R phase, S phase, and T phase. By using this electric energy sensor, there is an advantage that a plurality of voltage sensors need not be used and other data such as electric energy can be acquired.

  The control unit 120 includes a first control device 121, a second control device 122, and a third control device 123. The first control device 121, the second control device 122, and the third control device 123 are connected to each other via a communication line LN, and are configured to transfer data to each other based on a CAN (Controller Area Network) standard.

  The first control device 121, the second control device 122, and the third control device 123 include processing units 121a, 122a, and 123a such as a CPU (Central Processing Unit), a nonvolatile memory such as a ROM (Read Only Memory), and a flash memory. Storage units 121b, 122b, and 123b each including a rewritable nonvolatile memory and a volatile memory such as a RAM (Random Access Memory).

  The power supply circuit monitoring system 100 includes a control program stored in advance in the ROM of the storage units 121b, 122b, and 123b by the processing units 121a, 122a, and 123a of the first control device 121, the second control device 122, and the third control device 123. Various components are controlled by loading and executing on the RAMs of the storage units 121b, 122b, and 123b. The nonvolatile memories in the storage units 121b, 122b, and 123b store various system information such as operation parameters and setting data of the power supply circuit monitoring system 100.

  The first controller 121 is configured to transmit the interphase voltages Vrs, Vst, Vtr detected by the voltage sensor 110 to the second controller 122.

  The second control device 122 is configured to record the interphase voltages Vrs, Vst, and Vtr sent from the first control device 121.

  FIG. 2 is a system block diagram mainly showing the second control device 122 in the control unit 120 shown in FIG.

  As shown in FIG. 2, the second control device 122 includes recording control means P1 that records the interphase voltages Vrs, Vst, and Vtr sent from the first control device 121 in the storage unit 122b, and the first control device 121. To the unbalance determination means P2 for determining whether or not the interphase voltages Vrs, Vst, and Vtr that have been sent are unbalanced (including unphased, the same applies hereinafter) and the auxiliary machine 30 of the three-phase power supply circuit 10 When the power supply monitoring control means P3 for monitoring whether or not the power supply is interrupted and the unbalance determination means P2 determine that the interphase voltages Vrs, Vst, Vtr are unbalanced, or the power supply monitoring control means P3 And an alarm issue control means P4 that issues an alarm when it is determined that the power supply to the auxiliary machine 30 of the three-phase power supply circuit 10 is cut off.

  The power supply circuit monitoring system 100 further includes a display unit 124. The display unit 124 is electrically connected to the output system of the second control device 122 so that the display information from the second control device 122 is output.

  Specifically, the recording control means P1 records the interphase voltages Vrs, Vst, and Vtr sent from the first control device 121 in the nonvolatile memory of the storage unit 122b at predetermined sampling times. Here, there are a plurality of auxiliary machines 30. Therefore, the recording control unit P1 uses the interphase voltages Vrs, Vst, and Vtr sent from the first control device 121 together with information on the installation location (information indicating the location where the auxiliary machine 30 is installed) for a predetermined sampling time. Every time it is recorded in the non-volatile memory of the storage unit 122b. Note that the recording control means P1 may record the interphase voltages Vrs, Vst, Vtr together with the information on the installation location and the date and time (date and time).

The unbalance determination means P2 uses a predetermined determination formula (in this example, refer to [Formula 1] of the voltage unbalance rate [%] shown below) using the interphase voltages Vrs, Vst, and Vtr as parameters. When the value of the judgment formula [Formula 1] exceeds a predetermined threshold (for example, 5 [%]) calculated, the interphase voltages Vrs, Vst, and Vtr are regarded as unbalanced. Needless to say, the determination formula is not limited to [Formula 1] of the following voltage unbalance rate.
| MAX (Vrs−Va, Vst−Va, Vtr−Va) | / Va × 100 (Formula 1)
However, Va = (Vrs + Vst + Vtr) / 3
| MAX (α, β, γ) |: Select the maximum value among the absolute values of α, β, γ. The power supply monitoring control means P3 is the first of the electromagnetic contactor 22 (see FIG. 4) in the auxiliary circuit 20. An identification signal indicating whether the one contact portion 22r, 22s, 22t is on or off is detected.

  When the alarm generation control unit P4 determines that the interphase voltages Vrs, Vst, Vtr are unbalanced by the unbalance determination unit P2, the monitoring including the values of the interphase voltages Vrs, Vst, Vtr in the storage unit 122b is performed. Data is transmitted to the display unit 124 and / or the third control device 123. Specifically, the alarm notification control means P4 indicates that the values of the interphase voltages Vrs, Vst, Vtr in the storage unit 122b determined to be unbalanced and the interphase voltages Vrs, Vst, Vtr are unbalanced. The message is transmitted as monitoring data to the display unit 124 and / or the third control device 123 together with the information on the installation location. Information about which of the monitoring data is transmitted to the display unit 124 and the third control device 123 can be set in advance.

  Then, the second control device 122 displays the values of the interphase voltages Vrs, Vst, Vtr determined to be unbalanced by the alarm generation control means P4 and the message indicating that the balance is unbalanced together with the information on the installation location. When transmitted to the display unit 124, these monitoring data are displayed on the display screen of the display unit 124. The third control device 123 sends from the second control device 122 the values of the interphase voltages Vrs, Vst, and Vtr determined to be unbalanced and a message indicating that the balance is unbalanced together with information on the installation location. In such a case, the monitoring data is transmitted to a remote monitoring device 300 (see FIG. 1) described later.

  Further, when the power supply monitoring control unit P3 detects a signal indicating the off state of the first contact portions 22r, 22s, and 22t, the alarm issue control unit P4 detects the interphase voltages Vrs, Vst, and Vtr in the storage unit 122b. The monitoring data including the value is transmitted to the display unit 124 and / or the third control device 123. Specifically, the alarm notification control unit P4 is configured to output the interphase voltage in the storage unit 122b that is a predetermined time (predetermined number of samples) from the time when the power supply to the auxiliary machine 30 of the three-phase power supply circuit 10 is interrupted. The values of Vrs, Vst, and Vtr and a message that the power supply to the auxiliary machine 30 of the three-phase power supply circuit 10 has been cut off are displayed as monitoring data on the display unit 124 and / or the third control device 123 together with information on the installation location. Send. Information about which of the monitoring data is transmitted to the display unit 124 and the third control device 123 can be set in advance.

  Then, the second controller 122 sends the values of the interphase voltages Vrs, Vst, and Vtr that are traced back from the shut-off time by the alarm alert control means P4 and the message that the power feeding is cut off along with the information on the installation location. When transmitted to the display unit 124, these monitoring data are displayed on the display screen of the display unit 124. The third control device 123 sends from the second control device 122 the values of the interphase voltages Vrs, Vst, and Vtr that have been traced back from the shut-off time, and a message that the power supply has been cut off along with the information on the installation location. In this case, the monitoring data is transmitted to the remote monitoring device 300.

  The second control device 122 can be connected to a terminal device 125 such as a personal computer or a portable terminal, so that the terminal device 125 can capture the monitoring data stored in the second control device 122. It has become.

  The remote monitoring device 300 (see FIG. 1) is connected to the third control device 123 via a communication network 310 such as a public line network. The third control device 123 and the remote monitoring device 300 can exchange information with each other. The remote monitoring device 300 is disposed in a remote monitoring center located far away from the power supply circuit monitoring system 100, and collects and accumulates monitoring data from the power supply circuit monitoring system 100. The remote monitoring device 300 can be connected to terminal devices 330 to 330 such as personal computers and portable terminals via a network 320 such as a LAN (Local Area Network). The monitoring data accumulated in the monitoring device 300 can be captured.

  Next, an example of a control operation by the second control device 122 of the control unit 120 in the power supply circuit monitoring system 100 will be described with reference to FIG.

  FIG. 3 is a flowchart illustrating an example of a control operation by the second control device 122 of the control unit 120 in the power supply circuit monitoring system 100.

  As shown in FIG. 3, first, the second control device 122 acquires the interphase voltages Vrs, Vst, Vtr from the first control device 121 for each sampling time (step S1), and acquires the acquired interphase voltages Vrs, Vst, Vtr. Are recorded in the storage unit 122b together with information on the installation location (step S2).

Next, the second control device 122 calculates the voltage unbalance rate by substituting the interphase voltages Vrs, Vst, and Vtr into [Formula 1] of the voltage unbalance rate that is the determination formula (step S3), and the calculated value is It is determined whether or not a threshold value (for example, 5%) has been exceeded (step S4). When it is determined that the calculated value exceeds the threshold (step S4: Yes), the values of the interphase voltages Vrs, Vst, Vtr determined to be unbalanced and the interphase voltages Vrs, Vst, Vtr are unbalanced. A message to the effect is transmitted to the display unit 124 and / or the third control device 123 together with the information on the installation location (step S5), and the process proceeds to step S6, while the calculated value is determined not to exceed the threshold value. (Step S4: No), the process proceeds to Step S6 as it is. Next, in the second control device 122, the first contact portions 22r, 22s, and 22t of the electromagnetic contactor 22 (see FIG. 4) in the auxiliary circuit 20 are turned on. An identification signal indicating whether the first contact portion 22r, 22s, or 22t is on is detected (step S6). Or a signal indicating an off state (step S7). When the identification signal is a signal indicating the off state of the first contact portions 22r, 22s, and 22t (step S7: off state), the power supply to the auxiliary machine 30 of the three-phase power supply circuit 10 is cut off from the cutoff point. The values of interphase voltages Vrs, Vst, and Vtr that are traced back by a predetermined time (predetermined number of samples) and a message that power supply to the auxiliary machine 30 of the three-phase power supply circuit 10 is cut off are displayed together with information on the installation location. When the identification signal is a signal indicating the ON state of the first contact portions 22r, 22s, 22t (step S8), the process proceeds to step S9 (step S8). S7: ON state), the process proceeds to step S9.

  Next, the second control device 122 repeats the processes of steps S1 to S9 until an instruction to end the process (step S9: No), and ends the process when there is an instruction to end the process (step S9: Yes). To do.

  As described above, according to the power supply circuit monitoring system 100 according to the present embodiment, the recording control unit P1 records the interphase voltages Vrs, Vst, and Vtr detected by the voltage sensor 110, so that the The control unit 120 can monitor the interphase voltages Vrs, Vst, and Vtr, so that the factor that cuts off the power supply to the auxiliary machine 30 of the three-phase power supply circuit 10 is a factor on the three-phase power supply circuit 10 side. Or a factor on the thermal relay 21 side can be identified.

  For example, when the power supply to the auxiliary machine 30 of the three-phase power supply circuit 10 is cut off (step S7: OFF state), the supervisor or the control unit 120 performs the display unit 124 and / or the third control by the transmission operation in step S5. The interphase voltages Vrs, Vst, Vtr determined to be unbalanced sent to the device 123, and the predetermined time from the cutoff time sent to the display unit 124 and / or the third control device 123 by the transmission operation in step S8. By checking the interphase voltages Vrs, Vst, and Vtr that are traced back by the time (predetermined number of samples), an open phase has occurred in the three phases of the R-phase, S-phase, and T-phase in the three-phase power supply circuit 10, or Assuming that the interphase voltages Vrs, Vst, and Vtr between the three phases are unbalanced, the factor that cuts off the power supply to the auxiliary machine 30 of the three-phase power supply circuit 10 is a factor on the three-phase power supply circuit 10 side. It is possible to identify the Rukoto.

  Further, when the power supply to the auxiliary machine 30 of the three-phase power supply circuit 10 is cut off (step S7: OFF state), the supervisor or the control unit 120 performs the display unit 124 and / or the third control by the transmission operation in step S8. The interphase voltages Vrs, Vst, and Vtr between the three phases of the three-phase power supply circuit 10 are balanced with respect to the interphase voltages Vrs, Vst, and Vtr that have been sent to the device 123 by a predetermined time (predetermined number of samples) from the cutoff point. As a result of confirming that the power supply is maintained, the factor causing the power supply to the auxiliary device 30 of the three-phase power supply circuit 10 to be cut off is the factor on the thermal relay 21 side even if the thermal relay 21 itself malfunctions. Can be identified.

  Note that the configuration of the thermal relay 21 in the auxiliary circuit 20 is not limited to that shown in FIG. 4, and any configuration can be used as long as the overheating of the auxiliary device 30 due to overcurrent can be protected. Good. Further, here, a thermal type thermal relay is used as the thermal relay 21, but when a current exceeding a predetermined value is detected by separately providing a detection control means, a three-phase is detected by the electromagnetic contactor 22. An electronic thermal relay that cuts off the power supply from the power supply circuit 10 to the auxiliary machine 30 may be used.

  In the present embodiment, a three-phase three-wire circuit is used as the three-phase power supply circuit, but a three-phase four-wire circuit may be used.

  The present invention is not limited to the embodiment described above, and can be implemented in various other forms. Therefore, such an embodiment is merely an example in all respects and should not be interpreted in a limited manner. The scope of the present invention is shown by the scope of claims, and is not restricted by the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Three-phase power circuit 20 Auxiliary machine circuit 21 Thermal relay 21a Contact part 21r Thermal part 21t Thermal part 22 Electromagnetic contactor 22a Electromagnetic coil 22b Second contact part 22r First contact part 22s First contact part 22t First contact part 23 First push button switch 24 Second push button switch 30 Auxiliary machine 100 Power supply circuit monitoring system 110 Voltage sensor (an example of detection means)
120 control unit 121 first control device 121a processing unit 121b storage unit 122 second control device 122a processing unit 122b storage unit 123 third control device 123a processing unit 123b storage unit 124 display unit 125 terminal device 200 power supply connection circuit 300 remote monitoring device 310 communication network 320 network 330 terminal device L1 electric circuit L2 electric circuit LN communication line Lrs load Lst load Ltr load P1 recording control means P2 imbalance determination means P3 power supply monitoring control means P4 alarm reporting control means Prs electric power Pst electric power Ptr electric power Vrs phase voltage Vst Interphase voltage Vtr Interphase voltage

Claims (1)

A power circuit monitoring system for monitoring a power supply state from the three-phase power circuit of an auxiliary machine that is fed from the three-phase power circuit through the thermal relay of the auxiliary circuit having a thermal relay,
A detecting means for detecting an interphase voltage between three phases of the three-phase power supply circuit; and a recording control means for recording the interphase voltage detected by the detecting means ;
The interphase voltage recorded by the recording control means is monitored, and when the power supply to the auxiliary machine of the three-phase power supply circuit is cut off, the factor that cuts off the power supply to the auxiliary machine of the three-phase power supply circuit is A power supply circuit monitoring system for identifying whether the cause is on the three-phase power supply circuit side or on the thermal relay side .

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