JP2012061968A - Stationary power supply device unit for aircraft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stationary power supply device unit for aircrafts, capable of performing protection action by securely detecting an earth fault if the earth fault occurs, while maintaining a power supply state without performing earth fault detection if a loop circuit occurs, when power is supplied by a plurality of constant voltage constant frequency devices (CVCF) to one aircraft.SOLUTION: At least one set of a zero-phase-sequence current transformer 4, and an earth fault over-current relay 5 connected to the zero-phase-sequence current transformer 4, is prepared as a stationary power supply device unit X for aircrafts, which includes a plurality of three-phase four-line stationary power supply devices 1A and 1B for supplying power to an aircraft P under parking. When power is supplied to one aircraft P, all three-phase and neutral phase electric lines 2a, 2b, 2c and 3 of the stationary power supply devices 1A and 1B are connected to a load of the aircraft P, while the electric line 3 of the neutral phase is grounded to a body of the aircraft P, and a ground line 32 of each of the stationary power supply devices 1A and 1B is connected to the same ground electrode G through the common zero-phase-sequence current transformer 4.

Description

  The present invention relates to an aircraft static power supply unit including a plurality of static power supply devices.

  As a device for supplying electric power to an aircraft parked at an airport, a power conversion type static power supply device using a semiconductor is known (Non-Patent Document 1). If power is supplied to an aircraft with such a power conversion type static power supply device using a semiconductor, it is not necessary to drive the engine, and CO2 emissions can be greatly reduced.

  As shown in FIG. 6, such an environmentally friendly static power supply device has a three-phase four-wire power transmission circuit, a zero-phase current transformer (ZCT) 4 ′, and a ground fault excess. Examples thereof include a constant voltage constant frequency (CVCF) 1 ′ having a current relay 5.

  The constant voltage constant frequency device 1 'is one of control methods for a fixed voltage / fixed frequency inverter and supplies alternating current with a certain voltage and frequency. When power is supplied to the aircraft P by the constant voltage constant frequency device 1 ′ (hereinafter sometimes referred to as “CVCF1 ′”), as shown in FIG. 6, the three-phase electric wires 2a ′, 2b ′, 2c ′ , And the neutral phase wire 3 ′ connected to the neutral point N is connected to the load in the fuselage P, and the neutral phase wire 3 ′ is connected to the fuselage P to obtain the body ground (Pg) ( Body ground wire 31 '). Further, the neutral phase grounding wire 32 ′ is connected to the grounding electrode G outside the machine body P.

  In addition, ZCT 4 ′ through which the three-phase and neutral-phase electric wires 2a ′, 2b ′, 2c ′, 3 ′ (total of four wires) are collectively passed is secondary in a normal state where no ground fault has occurred. By utilizing the fact that current does not flow to the side, the current flowing to the secondary side of ZCT4 ′ when the three-phase current balance is lost, that is, when a ground fault occurs, is connected to this secondary side. The overcurrent relay 5 ′ detects and issues an alarm. In some cases, the contactor 6 'is opened to shut off the power transmission circuit (stop the power transmission state).

Sinfonia Technology Co., Ltd., “400Hz static power supply for aircraft”, November 2004

  By the way, with the recent increase in size of aircraft, a CVCF capable of supplying such a large amount of power is required for large aircraft that require a large-capacity power supply, but rather than increasing the power supply of a single CVCF. It is more realistic to supply power using a plurality of CVCFs having the conventional power supply capability. Accordingly, in accordance with the example shown in FIG. 6, as shown in FIG. 7, the three-phase and neutral-phase electric wires 2a ′, 2b ′, 2c ′ of a plurality (two in the figure) of CVCFs 1A ′, 1B ′. , 3 'are connected to the load of the airframe P, and the neutral phase wires 3' of the CVCFs 1A ', 1B' are branched to body ground wires 31 'which are respectively body-grounded (Pg) to the airframe P, and each CVCF1A When the ', 1B' ground line 32 'is connected to the separate ground poles G and Gx, the following problems may occur.

  That is, when an unbalance occurs in the neutral phase due to a difference in load on each CVCF 1A′1B ′, as shown by an arrow in FIG. 7, the ground line 32 ′ (ground pole G) of one CVCF 1A ′ → the other CVCF1B ′ ground line 32 ′ (ground pole Gx) → neutral phase body ground point Pg of the other CVCF1B ′ → neutral phase body ground point Pg of one CVCF1A ′ → ground line 32 ′ of one CVCF1A ′ A circuit that passes through (the ground electrode G) is formed, and the current of the neutral phase increases, so that the current flows to the secondary side of each ZCT 4 ′, and the current is detected by the ground fault overcurrent relay 5 ′. Thus, the ground fault overcurrent relay 5 ′ erroneously determines that a ground fault has occurred, and issues an alarm. In some cases, the contactor 6 'is opened to shut off the power transmission circuit (stop the power transmission state).

  The inventors of the present invention have a problem when a plurality of CVCFs are simply connected to the same aircraft, that is, the load on each CVCF is unloaded with a plurality of CVCFs connected to one aircraft. When a balance occurs, a circuit that wraps around each ZCT is formed, current flows to the secondary side of the ZCT, and the same processing as when a ground fault is detected (malfunction) In order to solve such problems, the inventors have come up with the stationary power supply unit for aircraft of the present invention.

  The main object of the present invention is that when a ground fault occurs when power is supplied to a single aircraft with a plurality of CVCFs, the ground fault can be reliably detected and a protection operation can be performed. A stationary power supply unit for aircraft that can maintain the power supply state without erroneously detecting that a ground fault has occurred when a turning circuit occurs, and that can simultaneously supply power to multiple aircraft depending on the situation. It is to provide.

  That is, the present invention relates to an aircraft static power supply unit including a plurality of three-phase four-wire static power supply devices that supply power to a parked aircraft. The aircraft static power supply unit of the present invention includes at least one set of a zero-phase current transformer and a ground fault overcurrent relay connected to the zero-phase current transformer. When supplying power, connect all three-phase and neutral-phase electric wires of each static power supply to the fuselage load, ground the neutral-phase electric wires to the fuselage, and ground the static power supply Are connected to the same grounding pole through a common zero-phase current transformer. Here, it is obvious that the grounding wire is a neutral phase wire, and “the grounding wire of each static power supply device” means “the neutral phase grounding wire of each static power supply device”.

  With such an aircraft static power supply unit according to the present invention, when power is supplied to one aircraft, a common ground line is used for each static power supply (hereinafter sometimes referred to as “CVCF”). This is a case where an unbalance occurs in the neutral phase of each CVCF by passing through a zero-phase current transformer (hereinafter sometimes referred to as “ZCT”), and a rotating circuit is formed due to this unbalance. However, the current flowing through the rotating circuit can be canceled by the current passing through the common ZCT in the opposite direction to this current, and no current flows on the secondary side of the ZCT. Thereby, it can prevent that a ground fault overcurrent relay detects a zero phase current (ground fault current) accidentally.

  In this way, the static power supply unit for an aircraft according to the present invention that can prevent erroneous detection of a ground fault, in the case of a ground fault, of the ground phase CVCF out of the neutral phase ground line passing through the ZCT, Since the current flows only in the neutral phase, the ground fault overcurrent relay detects the current flowing on the secondary side of the ZCT as a zero-phase current (ground fault current) and can perform a protection operation. Here, examples of the protective operation include an operation for issuing an alarm, and an operation for stopping the power supply state when an appropriate switch or circuit breaker is provided. Thus, when a ground fault occurs, a ground fault can be detected appropriately and a protection operation can be performed.

  In addition, in the present invention, each stationary power supply unit can be configured as an aircraft stationary power supply unit that includes a zero-phase current transformer and a ground fault overcurrent relay. When supplying power to one aircraft, connect the ground wire of each stationary power supply to the same grounding electrode through a common zero-phase current transformer, When power is supplied by the type power supply device, it is preferable that the ground line of each static power supply device is individually passed through the zero-phase current transformer of each static power supply device and connected to different grounding electrodes.

  As a result, when supplying power to one aircraft, the grounding wire of each stationary power supply device is connected to the same grounding electrode through a common zero-phase current transformer, thereby providing the above-described effects. Can be obtained. In addition, using the aircraft static power supply unit of the present invention, the ground wire of each static power supply device is individually passed through the zero-phase current transformer of each static power supply device and connected to different ground electrodes. Makes the relationship between each stationary power supply and each aircraft conform to the conventional relationship, and can transmit power to each aircraft, and if a ground fault occurs, the ground fault is detected appropriately Then, the protection operation is performed. As described above, with the aircraft static power supply unit of the present invention, for a large aircraft that requires a large capacity power supply, the single mode for supplying power to one aircraft is selected, and a large capacity power supply is required. For medium-sized and small aircraft that are not, it is preferable that a multi-mode that supplies power to a plurality of aircrafts can be selected so that power can be supplied individually by a stationary power supply device.

  To efficiently and smoothly select a zero-phase current transformer that passes the ground wire and a grounding electrode that connects the ground wire when power is supplied to one aircraft and when power is supplied to multiple aircraft To connect the ground wire of each static power supply unit to the same grounding electrode through a common zero-phase current transformer, and connect the ground wire of each static power supply device to the zero phase of each static power supply device It is preferable to provide a static power supply unit for aviation provided with a switching mechanism that selectively switches between a state in which the current is individually passed through a current transformer and connected to a different ground electrode. As an example of the switching mechanism, a single-mode electromagnetic contactor that can connect the ground wire of each static power supply device to the same ground electrode through a common zero-phase current transformer, and the ground wire of each static power supply device A multimode electromagnetic contactor that can be individually connected to a zero-phase current transformer of each stationary power supply unit and can be connected to different grounding poles, and supplying power to one aircraft, A configuration in which the electromagnetic contactor used (turned on) is switched between when power is supplied to each aircraft by each stationary power supply device.

  According to the present invention, when a plurality of static power supply units (CVCF) are connected to one aircraft at the same time, each circuit configuration sharing a zero-phase current transformer (ZCT) for ground fault detection Even when the neutral phase is unbalanced due to the difference in load with respect to the CVCF and a rotating circuit is formed, by canceling the current flowing through the rotating circuit, ground faults are prevented while preventing erroneous detection of ground faults. When it occurs, the ground fault current (zero phase current) is detected by ZCT, and a ground fault overcurrent relay can be used to perform a protection operation. In addition, each static power supply device is provided with a zero-phase current transformer and a ground fault overcurrent relay, and the ground wire of each static power supply device is individually passed through the zero-phase current transformer of each static power supply device to be different from each other. By connecting to the ground electrode, it is possible to simultaneously supply power to a plurality of aircraft by each stationary power supply.

1 is an overall configuration schematic diagram of an aeronautical static power supply unit according to an embodiment of the present invention. FIG. 1 is a diagram corresponding to FIG. 1 of a variation of an aeronautical static power supply unit according to the embodiment. FIG. 3 is a diagram corresponding to FIG. 2 in the multi-mode in the static power supply unit for aviation. FIG. 1 is a diagram corresponding to FIG. 1 of a variation of an aeronautical static power supply unit according to the embodiment. FIG. 5 is a diagram corresponding to FIG. 4 in the multi-mode in the static power supply unit for aviation. FIG. 2 is a schematic diagram of the overall configuration of a conventional static power supply device for aviation. FIG. 6 is a diagram corresponding to FIG. 6 when power is supplied to a common aircraft by using a plurality of conventional aeronautical static power supply devices.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, an aircraft static power supply unit X according to the present embodiment includes a plurality of static power supply devices 1A and 1B (hereinafter referred to as “CVCF1A and 1B”), and the plurality of CVCF1A and 1B. The electric power is supplied to the aircraft P that is parked.

  A structure common to the CVCFs 1A and 1B will be described. Each CVCF 1A, 1B is a three-phase AC power source using three-phase (first phase R, second phase S, third phase T) AC, and in this embodiment, one end of each of the three-phase R, S, T. Are connected to a common neutral point N (Y connection). That is, these CVCFs 1A and 1B are composed of three electric wires 2a, 2b and 2c of each of the three phases R, S and T and three electric wires 3 (neutral wires 3) connected to the neutral point N. The phase AC power can be supplied to the aircraft P. Further, the neutral wire 3 is branched into a body ground wire 31 connected to the body ground point Pg of the airframe P and a ground wire 32 connected to the ground electrode G outside the aircraft P.

  In addition, the static power supply unit X for an aircraft of the present embodiment is connected to a three-phase four-wire power transmission circuit 10 with a zero-phase current transformer 4 (hereinafter referred to as “ZCT4”) and a secondary side of the ZCT4. A ground fault overcurrent relay 5 is provided in association with it. Since ZCT4 and the ground fault overcurrent relay 5 can apply a well-known thing, detailed description is abbreviate | omitted. In addition, the circuit breaker which can interrupt | block an electric current is connected to the ground fault overcurrent relay 5 (illustration omitted).

  When the power supply unit X for aircraft according to the present embodiment supplies power to one aircraft P by a plurality of CVCFs 1A and 1B (2 systems in the illustrated example), four CVCFs 1A and 1B are used. Are connected to the load of the fuselage P, and the grounding wires 32 of the CVCFs 1A and 1B are connected to a common ZCT 4 as well as the three-phase electric wires 2a, 2b and 2c and the neutral phase electric wires 3 respectively. And are connected to the same ground electrode G. Further, neutral phase body ground wires 31 of the CVCFs 1A and 1B are connected to the body P (body ground). In the present embodiment, an ON state in which the electric wires 2a, 2b, 2c of the three-phase R, S, T and the electric wire 3 of the neutral phase can be connected to the load of the aircraft P by the magnetic contactor 6 (contactor 6). And can be switched between an OFF state incapable of connection.

  In the state where the four electric wires 2a, 2b, 2c, 3 of each CVCF 1A, 1B are connected to the load of the airframe P and the contactor 6 is set to the ON state, one aircraft P When power is supplied to the CVCF 1A and 1B, the neutral phase may be unbalanced in the neutral phase of the CVCF 1A and 1B. At that time, the neutral phase 3 of each of the middle CVCFs 1A and 1B forms a circuit around each body ground point Pg of the airframe P as indicated by an arrow in FIG. And, it is considered that the neutral phase current flowing through the circuit around the CVCFs 1A and 1B may be almost the same as the current at the time of grounding due to the difference in the load on each CVCF 1A and 1B.

  However, since the static power supply unit X of the present embodiment passes the ground line 32 of each CVCF 1A, 1B through the common ZCT 4, there is a case where a rotating circuit due to the unbalance of the neutral phase 3 is formed. Even in such a case, since the current of the circuit flowing through the neutral phase 3 passes through the ZCT 4 in both directions, the vector sum of the current flowing through the circuit can be made zero. As a result, no current flows on the secondary side of the ZCT 4, and it is possible to prevent the current from flowing to the ground fault overcurrent relay 5 connected to the secondary side of the ZCT 4 to prevent the protection operation from being erroneously performed. The power supply to P can be continued in a stable state.

  On the other hand, when a ground fault occurs in any of the electric wires 2a, 2b, 2c, current flows only through the grounded ground wires 32 of the grounded CVCFs 1A and 1B among the ground wires 32 passing through the common ZCT 4. A current flows through the secondary side of ZCT 4 and the ground fault overcurrent relay 5 detects the current (zero-phase current) by the ground fault overcurrent relay 5, so that the ground fault overcurrent relay 5 can perform a protection operation. Here, as a protection operation, an operation for issuing an alarm (in this case, the output may be manually interrupted by receiving the alarm (for example, pressing an output off button or an emergency stop button)), or an alarm is issued. Instead or in addition, an operation of opening the contactor 6 and automatically stopping the power supply state can be given.

  As described above, the static power supply unit X for aircraft of the present embodiment connects the ground line 32 of each CVCF 1A, 1B to the single ground pole G through the common ZCT 4, so that the CVCF 1A, 1B is connected to each CVCF 1A, 1B. When a rotating circuit is formed due to load imbalance, it is possible to prevent the ground fault overcurrent relay 5 from erroneously detecting a zero-phase current (ground fault current), and when a ground fault actually occurs. Can detect the ground fault current (zero phase current) by the ground fault overcurrent relay 5 and can appropriately perform the protection operation.

  In addition, this invention is not limited to embodiment mentioned above. For example, as shown in FIGS. 2 and 3, each CVCF 1A, 1B is provided with a separate ZCT 4, 4x and a ground fault overcurrent relay 5, 5x, respectively, to supply power to one aircraft P (see FIG. 2) and a multi-mode (see FIG. 3) for supplying power to a plurality of aircrafts P, the ZCT passing through the ground line 32 of each CVCF 1A, 1B can be changed, and each CVCF 1A, It can also be set as the static power supply unit X for aircrafts which can change (switchable) the ground pole which connects the 1B ground line 32. FIG. As an example of such an aircraft static power supply unit X, the ground line 32 of each CVCF 1A, 1B is connected to the same ground electrode G through a common ZCT 4, and the ground line 32 of each CVCF 1A, 1B. Is preferably provided with a switching mechanism for selectively switching between a state where each of the CVCFs 1A and 1B is individually connected to ZCT4 and ZCT4x and connected to different grounding electrodes G and Gx.

  Specifically, in the case of an aircraft static power supply unit X having a 1-system CVCF 1A and a 2-system CVCF 1B, the switching mechanism is provided in the 2-system CVCF 1B, and the ground line 32 of the 2-system CVCF 1B is connected. A first contactor 61 (“single-mode electromagnetic contactor”) for connecting to the same grounding pole G as the grounding pole G of the grounding line 32 of the CVCF1A through the ZCT4 common to the grounding line 32 of the 1-system CVCF1A; In addition, the ground line 32 of the second system CVCF 1B is passed through the ZCT 4x different from the ZCT 4 passing through the ground line 32 of the first system CVCF 1A, that is, the ZCT 4x provided in the second system CVCF 1B, and the ground pole G of the ground line 32 of the CVCF 1A Is a configuration in which the second contactor 62 (“multi-mode electromagnetic contactor”) for connection to a different ground electrode Gx is used. It can be. 2 and 3, when the first contactor 61 is used, the electric wires 2a, 2b, 2c, 3 of the second system CVCF 1B are connected to the electric wires 2a, 2b of the first system CVCF 1A. , 2c, 3 when connected to the same body P and the second contactor 62 is used, the wires 2a, 2b, 2c, 3 of the 2 system CVCF 1B are connected to the wires 2a, 2b, 2c, 3 of the 1 system CVCF 1A. It is configured to connect to a different body Px.

  When such a static power supply unit X supplies power to the same airframe P (single mode), as shown in FIG. 1, the first contactor 61 is used (the first contactor 61 is in the ON state). By setting the second contactor 62 to the OFF state (open state) in the (connected state), it is possible to obtain the same operational effects as those of the stationary power supply unit X for an aircraft described in the above-described embodiment.

  Further, when power is supplied to a plurality of airframes P and Px by the aircraft static power supply unit X (multi-mode), the second contactor 62 is used as shown in FIG. 3 (first contactor). 61 is turned off (open state), and the second contactor 62 is turned on (connected state). As a result, power is supplied to the corresponding airframes P in a state where the three-phase four-wire power transmission circuit 10 of the first system CVCF 1A and the three-phase four-wire power transmission circuit 10x of the second system CVCF 1B are electrically disconnected. In the relationship between each CVCF 1A, 1B and the airframes P, Px, power can be supplied in accordance with the conventional mode. When a ground fault occurs, the ground fault is caused by the ground fault overcurrent relays 5, 5x. The current (zero phase current) is detected, and the ground fault overcurrent relays 5 and 5x perform the protective operation.

  Further, as shown in FIGS. 4 and 5, in the case of configuring a static power supply unit X having three systems of CVCFs 1A, 1B, 1C, in addition to the configurations shown in FIGS. The ground wire 32 of the 3 system CVCF 1C is passed through the ZCT 4 common to the ground wires 32 of the 1 system and 2 systems CVCF 1A, 1B through the CVCF 1C of the 1 system and 2 systems CVCF 1A, 1B. A third contactor 63 (corresponding to the “single-mode electromagnetic contactor” of the present invention) for connecting to the same grounding electrode G as G, and the grounding wire 32 of the 3 system CVCF1C are connected to the grounding wire of the 1 system CVCF1A. The fourth and second CVCFs 1B and 4B are connected to a grounding pole Gy different from the grounding poles G and Gx of the grounding lines 32 of the 1st and 2nd CVCFs 1A and 1B through the ZCT 4y different from the grounding line 32 of the CVCF 1B. Contact 64 (corresponding to "multimode electromagnetic contactor" of the present invention) and may be provided. In addition, when the third contactor 63 is used, the stationary power supply unit X is configured so that the electric wires 2a, 2b, 2c, 3 of the 3 system CVCF 1C are connected to the electric wires 2a, 2b of the 1 system and 2 systems CVCF 1A, 1B, When the fourth contactor 64 is connected to the same body P as 2c, 3 and the fourth contactor 64 is used, the wires 2a, 2b, 2c, 3 of the 3 system CVCF 1C are connected to the wires 2a, 2b, 2c, 3 of the 1 system CVCF 1A. The electric wires 2a, 2b, 2c, 3 of the two-system CVCF 1B are connected to a different body Py.

  Then, as shown in FIG. 4, such a stationary power supply unit X uses the first contactor 61 and the third contactor 63 when supplying power to the same airframe P (single mode) (the first contactor 63). The contactor 61 and the third contactor 63 are turned on and the second contactor 62 and the fourth contactor 64 are turned off), so that the same effect as the stationary power supply unit X for an aircraft described in the above-described embodiment is obtained. Can be obtained.

  Further, when power is supplied to each of the three aircrafts P, Px, and Py (multimode), the second contactor 62 and the fourth contactor 64 are used as shown in FIG. 5 (the first contactor 61 and the first contactor 61). The third contactor 63 is turned off, and the second contactor 62 and the fourth contactor 64 are turned on (connected state). As a result, the 1-system CVCF1A, 2-system CVCF1B, and 3-system CVCF1C three-phase four-wire power transmission circuits 10, 10x, and 10y are individually connected to the corresponding airframes P, Px, and Py while being electrically disconnected from each other. Electric power can be supplied. And since it can supply electric power according to the conventional aspect in the relationship between each CVCF1A, 1B, 1C and each body P, Px, Py, when a ground fault arises, a ground fault overcurrent relay 5, The ground fault current (zero phase current) is detected by 5x, 5y, and the ground fault overcurrent relays 5, 5x, 5y perform the protective operation.

  In addition, a static power supply unit using three or more CVCFs can be configured by appropriately adjusting the number of ZCTs, ground fault overcurrent relays, and contactors according to the above-described configuration.

  In the above-described embodiment, the switching mechanism includes a plurality of electromagnetic contactors, and an example in which the electromagnetic contactor to be used is switched depending on whether the aircraft to be fed is one or a plurality of aircrafts is exemplified. Instead of, or in addition to, the electromagnetic contactor, the switching mechanism can be configured using other devices (such as a switch or a circuit breaker for wiring).

  In addition, the specific configuration of each part is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

1, 1A, 1B, 1C ... Static power supply (CVCF, 1 system CVCF, 2 systems CVCF, 3 systems CVCF)
2a, 2b, 2c ... three-phase wire 3 ... neutral phase wire 32 ... ground wire 4, 4x, 4y ... zero phase current transformer 5, 5x, 5y ... ground fault overcurrent relay P, Px, Py ... aircraft G , Gx, Gy ... Grounding electrode X ... Static power supply unit for aircraft

Claims (3)

This is a static power supply unit for aircraft equipped with multiple three-phase, four-wire static power supply units that supply power to a parked aircraft.
At least one set of a zero-phase current transformer and a ground fault overcurrent relay connected to the zero-phase current transformer,
When supplying power to one aircraft,
Connect all the three-phase and neutral-phase wires of each static power supply to the fuselage load, ground the neutral-phase wires to the fuselage, and connect the ground wire of each static power supply to the common zero A stationary power supply unit for aircraft, which is connected to the same grounding electrode through a phase current transformer. Each of the static power supply devices includes the zero-phase current transformer and the ground fault overcurrent relay,
When supplying power to one aircraft, connect the ground wire of each static power supply device to the same ground electrode through the common zero-phase current transformer,
When supplying power to a plurality of aircrafts by the respective static power supply devices, the grounding wires of the respective static power supply devices are individually passed through the zero-phase current transformers of the respective static power supply devices so that different ground electrodes are provided. The stationary power supply unit for aircraft according to claim 1, wherein the stationary power supply unit is configured to be connected to the aircraft. A state in which the ground wire of each stationary power supply device is connected to the same grounding electrode through the common zero-phase current transformer, and the ground wire of each stationary power device is connected to the zero phase of each stationary power device. The stationary power supply unit for an aircraft according to claim 2, further comprising a switching mechanism that selectively switches between a state of being individually connected to the current transformer and connected to different grounding poles.

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