JP6184294B2 - Condensation prevention device and condensation prevention method - Google Patents

Description

  The present invention relates to a dew condensation prevention device and a dew condensation prevention method.

  If condensation occurs in an internal mechanism such as an electric device due to a temperature change or the like, it may cause a failure or malfunction. Patent Document 1 describes that condensation is evaporated by applying a weak current to generate heat even when an electrical device is not in operation.

JP 2002-230961 A

  However, for example, when a coil of a rotating machine such as a generator connected to a large-capacity AC power source is caused to generate heat by passing a weak current from the AC power source to prevent condensation, the current is increased if the voltage is too high. Becomes too large and the fuse blows. Therefore, it is conceivable to reduce the voltage of the AC power supply by providing a transformation mechanism. However, if the voltage is too small, the current is insufficient and condensation cannot be prevented. When an anti-condensation device having such a transformation mechanism is to be provided between the AC power supply and the rotating machine, the degree of voltage to be stepped down by the anti-condensation device depends on the voltage of the AC power supply or the AC power supply and the rotation speed. It depends on the length and thickness of the cable connecting the machine. Therefore, it is desirable to provide a dew condensation prevention device that can be used for general purposes even when such a situation is different.

  This invention is made | formed in view of such a condition, and provides the dew condensation prevention apparatus which prevents the dew condensation of a rotary machine.

To solve the problems described above, one aspect of the present invention is a condensation prevention device for preventing dew condensation of a rotary machine having a coil connected to an AC power source, in parallel with the rotating machine with respect to the AC power source is connected to, and the AC said rotating machine is configured to be supplied a transformer the voltage steps down to a predetermined voltage of the power supply, and a measuring unit for measuring an electrical physical quantity in the transformer and between the rotating machine, wherein And a controller that controls the degree of step-down in the transformer based on the electrophysical quantity measured by the measuring unit.

  Further, according to one aspect of the present invention, the transformer unit includes at least one of a primary side circuit connected to the AC power source, a secondary side circuit connected to the coil of the rotating machine, and the primary side circuit and the secondary side circuit. And an adjustment unit for adjusting the voltage after transformation.

  In one embodiment of the present invention, the adjustment unit includes a first adjustment unit that adjusts the voltage in the primary circuit, and a second adjustment unit that adjusts the voltage in the secondary circuit.

  One embodiment of the present invention is the other of the first adjustment unit and the second adjustment unit based on the physical quantity of electricity obtained by adjusting the voltage with either one of the first adjustment unit or the second adjustment unit. The control part which adjusts further is provided.

Further, according to one embodiment of the present invention, the transformer unit is a transformer, the primary side circuit and the secondary side circuit each include a primary side coil and a secondary side coil, and the adjustment unit includes a primary side coil and a primary side coil , of a tap provided at a plurality of different positions Oite turns on at least one hand.

Another embodiment of the present invention, there is provided a rotary machine having a coil connected to an AC power source, which is connected rotary machine and in parallel, and step down the voltage of the AC power supply to a predetermined voltage to the AC power source A dew condensation prevention method for preventing dew condensation of the rotating machine using a transformer that can be supplied to the rotating machine, a measuring step of measuring an electrical physical quantity between the transformer and the rotating machine, and the measurement And a control step of controlling the degree of step-down in the transformer based on an electrical physical quantity.

  Further, according to one aspect of the present invention, in the above dew condensation prevention method, the transformer included in the dew condensation prevention device includes a primary side circuit connected to an AC power source, a secondary side circuit connected to a coil of a rotating machine, A first adjustment unit that adjusts the voltage in the primary circuit and a second adjustment unit that adjusts the voltage in the secondary circuit, and adjusts the voltage by either the first adjustment unit or the second adjustment unit. The step of further adjusting the other of the first adjustment unit and the second adjustment unit based on the physical quantity of electricity acquired in this way is provided.

  As described above, according to the present invention, the dew condensation preventing device for preventing the dew condensation of the rotating machine having the coil is connected to the AC power source and connected in parallel to the output system to the coil of the rotating machine. The transformer has a transformer that steps down the voltage of the AC power supply to a voltage that can supply a predetermined range of current to the coil of the rotating machine, and the transformer can adjust the voltage after transformation. Condensation can be prevented.

It is a figure which shows the structural example of the dew condensation prevention apparatus by one Embodiment of this invention. It is a figure which shows the structural example of the transformation part by the 1st Embodiment of this invention. It is a flowchart which shows the operation example of the dew condensation prevention apparatus by the 1st Embodiment of this invention. It is a figure which shows the structural example of the secondary side circuit by the 1st Embodiment of this invention. It is a figure which shows the structural example of the transformation part by the 2nd Embodiment of this invention. It is a figure which shows the structural example of the transformation part by the 3rd Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, an outline of the present embodiment will be described. FIG. 1 is a diagram illustrating a configuration example of a dew condensation prevention device 50 according to the present embodiment.
The motor generator 100 is a rotating machine having coils, and is a three-phase motor generator having three coils z that are impedance elements. The motor generator 100 is connected to an AC power source via a terminal u, a terminal v, and a terminal w. Terminal u and terminal v are connected to transformer 200 by terminals 5 and 10, respectively, and transformer 200 is connected to terminals 1 and 8 by terminals 4 and 9, respectively. Terminal 1 and terminal 8 are connected to terminal U and terminal V, respectively. Terminal u and terminal 5 are connected via switch 6 and fuse 7. The terminal 4 and the terminal 1 are connected via the switch 2 and the fuse 3. In parallel with this, the terminal u is connected to the terminal 1 via the switch 11, and the terminal v is connected to the terminal 1 via the switch 12. The terminal w is connected to the terminal W through the switch 13. The terminal U, the terminal V, and the terminal W are connected to an AC power source (for example, 400V).

  A path where the terminal u is connected to the terminal 1 via the switch 11, a path where the terminal v is connected to the terminal 8 via the switch 12, and a path where the terminal w is connected to the terminal W via the switch 13. Is an output system, and while the motor generator 100 is operating, the switch 2 and the switch 6 are in an OFF state, and the switch 11, the switch 12 and the switch 13 are in an ON state. On the other hand, when the operation of the motor generator 100 is stopped, the switch 2 and the switch 6 are turned on, and the switch 11, the switch 12 and the switch 13 are turned off. Thereby, only the path | route which goes through the transformation part 200 will be in an energized state. In the present embodiment, while the operation of the motor generator 100 is stopped, only the path passing through the transformer 200 is energized, and the voltage of the AC power supply is reduced to energize the motor generator 100 with a weak current. As a result, heat is generated to prevent dew condensation, and a decrease in insulation capacity is suppressed.

The dew condensation prevention device 50 includes a transformer 200, a measuring instrument 300, and a controller 400.
The transformer 200 is connected to an AC power source via the terminal 1 and the terminal 8, and is connected in parallel to the output system to the coil z of the motor generator 100 via the terminal u and the terminal v. The voltage of the AC power supply is lowered to a voltage that can supply a predetermined range of current to the coil z of the motor generator 100. The voltage capable of supplying a predetermined range of current is, for example, 10V. As a result, a weak current is applied to the motor generator 100 to generate heat, thereby preventing condensation of the coil z in the motor generator 100. Here, if the voltage is too high and the current flows too much, the fuse 7 is blown. On the other hand, if the voltage is too low and the current is insufficient, the coil and its surroundings are brought to a temperature sufficient to prevent condensation of the motor generator 100. The temperature cannot be raised. Moreover, when connecting the dew condensation prevention apparatus 50 provided with such a transformation part 200 between the motor generator 100 and AC power supply as a general purpose apparatus, the voltage of AC power supply, AC power supply and motor generator 100, The degree of voltage to be stepped down by the transformer 200 varies depending on the length, thickness, etc. of the cable connecting the cables. Therefore, the transformer 200 according to the present embodiment can adjust the voltage after transformation in order to step down the voltage to an appropriate range so that the voltage is not too high and not too low even in such a situation. It is. Here, the transformer 200 can also adjust the degree of transformation in both the primary side circuit on the input side connected to the AC power source and the secondary side circuit on the output side connected to the motor generator 100. .

  The measuring device 300 is a device that is connected between the transformer 200 and the motor generator 100 and measures and outputs a physical quantity of electricity between the secondary circuit of the transformer 200 and the motor generator 100. The physical quantity of electricity is, for example, power, voltage, current, potential difference, voltage ratio, current ratio, and the like. The measuring instrument 300 is an oscilloscope, for example.

The control part 400 is a computer apparatus, for example, and controls the adjustment part with which the voltage transformation part 200 is provided. For example, when the transformer 200 adjusts the degree of transformation in both the primary side circuit and the secondary side circuit, the control unit 400 adjusts the voltage by either the primary side circuit or the secondary side circuit. Based on the acquired physical quantity of electricity, the other of the primary side circuit and the secondary side circuit is further adjusted.
Hereinafter, an embodiment of such a dew condensation prevention device 50 will be described in detail.

<First Embodiment>
With reference to the drawings, a dew condensation preventing apparatus 50 in the first embodiment will be described. FIG. 2 is a diagram illustrating a configuration example of a transformer unit 200a that is the transformer unit 200 included in the dew condensation prevention device 50 according to the present embodiment.
The transformer 200a includes a primary side circuit 200a-1 connected to an AC power source and a secondary side circuit 200a-2 connected to the coil z of the motor generator 100, and the primary side circuit 200a-1 Both the secondary side circuit 200a-2 are provided with the adjustment part which adjusts the voltage after transformation. In the present embodiment, the transformer 200a includes a tap terminal 201, a tap terminal 202, a tap terminal 203, a tap terminal 204 (first adjustment unit) that adjust the voltage in the primary circuit 200a-1, and a secondary circuit 200a-. 2 includes a tap terminal 205 for adjusting a voltage, a tap terminal 206, a tap terminal 207, and a tap terminal 208 (second adjustment unit). By providing such a plurality of tap terminals, it is possible to step down while adjusting the output voltage.

  In the present embodiment, the transformer unit 200a is a transformer, and the primary side circuit 200a-1 and the secondary side circuit 200a-2 include a coil. The primary side circuit 200 a-1 is connected to the AC power supply via the terminal 4 and the terminal 10. The secondary side circuit 200 a-2 is connected to the motor generator 100 via the terminal 5 and the switch 11. The tap terminal 201, the tap terminal 202, and the tap terminal 203 are taps provided at a plurality of positions having different numbers of turns in the coil of the primary side circuit 200a-1. The tap terminal 204 is connected to any one of the tap terminal 202, the tap terminal 202, and the tap terminal 203 to adjust the voltage. For example, the tap terminal 201 is provided at the position of the number of turns corresponding to 500V, the tap terminal 202 is provided at the position of the number of turns corresponding to 300V, and the tap terminal 203 is provided at the position of the number of turns corresponding to 200V.

  The tap terminal 205, the tap terminal 206, and the tap terminal 207 are taps provided at a plurality of positions having different numbers of turns in the coil of the secondary side circuit 200a-2. The tap terminal 208 is connected to any one of the tap terminal 205, the tap terminal 206, and the tap terminal 207 to adjust the voltage. For example, the tap terminal 205 is provided at the position of the number of turns corresponding to 8V, the tap terminal 206 is provided at the position of the number of turns corresponding to 7V, and the tap terminal 207 is provided at the position of the number of turns corresponding to 6V.

Next, an example of a method for controlling the dew condensation prevention device 50 according to the present embodiment will be described with reference to the drawings. FIG. 3 is a flowchart showing an operation example of the dew condensation prevention apparatus 50 according to the present embodiment.
The control unit 400 receives an input of a target value that is a voltage value necessary to prevent condensation of the coil z of the motor generator 100 (step S1). The target value may be a value such as “8V” or a range such as “6V to 9V”. Moreover, the control part 400 receives the input of the impedance estimated value of the secondary side circuit 200a-2 (step S2). Based on the target value input in step S1 and the estimated impedance value input in step S2, the control unit 400 taps the tap terminal 201, the tap terminal 202, and the tap in the secondary side circuit 200a-2. It is determined which of the terminals 203 is connected to the tap terminal 204, and the tap terminal 204 is connected to the determined tap terminal (step S3). For example, the control unit 400 determines the number of turns of the coil for stepping down the voltage of the AC power supply to the target value, and determines the tap terminal corresponding to the determined number of turns.

  And it supplies with electricity from AC power supply, and the measuring device 300 performs the test confirmation which measures the electricity supply state with respect to the motor generator 100 (step S4). Based on the measurement result of the measuring instrument 300, the control unit 400 adjusts the voltage by changing the connection of the tap terminals of the primary side circuit 200a-1 and the secondary side circuit 200a-2. For example, when the current is too large and exceeds the current capacity, or when the current saturation is caused by the magnetic saturation of the transformer core or the current waveform is distorted or becomes asymmetric between positive and negative, the tap terminal needs to be changed. First, the control unit 400 performs large adjustment of the degree of step-down by the secondary side circuit 200a-2 based on the measurement result by the measuring instrument 300. For example, if the measurement result is not 10% or more away from the target value, the control unit 400 proceeds to the next step. On the other hand, if the obtained measurement result is 10% or more away from the target value, in order to make the measurement result within 10% of the target value, the tap terminal 205, the tap terminal 206 in the secondary side circuit 200a-2, It is determined which of the tap terminals 207 is connected to the tap terminal 208, and the tap terminal 208 is connected to the determined tap terminal (step S5).

  Furthermore, the control unit 400 performs adjustment with a small degree of step-down by the primary side circuit 200a-1. For example, the control unit 400 calculates the estimated value of the voltage applied to the motor generator 100 after the adjustment in step S5, and further reduces the difference of 10% or less between the estimated value and the target value, so that the primary side circuit 200a. It is determined which of the tap terminal 201, the tap terminal 202, and the tap terminal 203 is connected to the tap terminal 204, and the tap terminal 204 is connected to the determined tap terminal (step S6).

In this manner, the dew condensation prevention device 50 adjusts the voltage of the AC power supply to a voltage that can supply a predetermined range of current to the coil z of the motor generator 100 and step down the voltage. As a result, a weak current with an optimal voltage can be applied to prevent condensation of the coil z of the motor generator 100.
The dew condensation prevention device 50 according to the present embodiment can be applied as, for example, a space heater circuit of a motor generator in a supercharger with a motor generator of a ship, and the dew condensation prevention device 50 is provided between an AC power source and a motor generator. It can be applied to prevent condensation of the motor generator coil. Here, particularly in a high-speed motor generator, the coil impedance (the vector sum of resistance and reactance) is very small, so it is necessary to step down the voltage to reduce the applied voltage.

  It is possible to step down the AC power supply by investigating the situation such as the voltage of the AC power supply in the ship in advance and bringing a transformer that performs a predetermined step-down. However, if a transformer cannot be installed in the immediate vicinity of the motor generator, it may be installed in the panel of an inverter or converter that controls them. In this case, if not only the internal impedance of the motor generator but also the impedance of the cable to the panel is not accurately taken into account, current shortage and overcurrent will occur, and the desired heat generation / heater effect cannot be obtained, The capacity of the fuse may be exceeded. The impedance of the cable differs depending on uncertain factors such as the installation location of the motor generator and the transformer, the wiring route, the length and thickness (cross-sectional area) of the cable, and the twisting method, and thus it is difficult to predict in advance. For this reason, even if a transformer is installed based on previously investigated information, if it cannot be stepped down to the optimum range due to the influence of such uncertain factors, a different transformer is manufactured, brought back and installed again. Such work is necessary.

  On the other hand, according to the dew condensation prevention device 50 of this embodiment, after bringing the dew condensation prevention device 50 into the ship and installing it, it is possible to perform an optimal step-down while measuring the actual voltage value, etc. It is possible to perform the optimum step-down in consideration of the uncertain factors corresponding to. In order to prevent the condensation of the coils of the motor generator in railway vehicles, airplanes, large vehicles, etc., the condensation prevention device 50 can be similarly applied.

  Further, for example, as in the above-described example, the AC power supply is 400V, and the primary circuit 200a-1 has a tap terminal of the tap terminal 201 (500V), the tap terminal 202 (300V), and the tap terminal 203 (200V). If the voltage measured by the measuring instrument 300 is 6V, the output is 12V by using the tap terminal 203 (200V), and the output is 4.8V by using the tap terminal 201 (500V). According to the dew condensation prevention device 50 of the present embodiment, the output voltage can be adjusted by such various combinations. Further, if the step of the tap terminal in the primary side circuit 200a-1 is reduced, the voltage can be adjusted more finely than the adjustment in the secondary side circuit 200a-2.

  In the above-described example, for example, the secondary side circuit 200a-2 includes the tap terminal 205 provided at the position of the number of turns corresponding to 8V and the number of turns corresponding to 7V in the coil of the secondary side circuit 200a-2. The input side tap terminal of the tap terminal 206 provided at the position and the tap terminal 207 provided at the position of the number of turns corresponding to 6V is provided, and one of these input side tap terminals is an output side tap terminal. The example in which a certain tap terminal 208 is connected to adjust the voltage has been described. Here, a plurality of output side tap terminals may be provided, and the degree of step-down may be adjusted according to the potential difference between the input side tap terminals to which the respective output side tap terminals are connected.

  FIG. 4 is a diagram illustrating a configuration example of the secondary side circuit 200a-2a which is such a secondary side circuit 200a-2. The secondary side circuit 200a-2a has, for example, a tap terminal 210 provided at a position of the number of turns corresponding to 7V, a tap terminal 211 provided at a position of the number of turns corresponding to 6V, and a position of the number of turns corresponding to 4V. An input-side tap terminal having a tap terminal 212 provided and a tap terminal 213 provided at the position of the number of turns corresponding to 0V is provided. Further, the secondary side circuit 200 a-2 a includes an output side tap terminal including a tap terminal 214 and a tap terminal 215. In this way, by connecting the output side tap terminals of the tap terminal 214 and the tap terminal 215 to any two input side tap terminals, the voltage can be flexibly reduced by the potential difference between the two input side tap terminals. The degree can be controlled.

For example, the first tap terminal 214 on the output side is connected to any one of the tap terminal 210 (7V), the tap terminal 211 (6V), and the tap terminal 212 (4V), and the second tap on the output side If the terminal 215 is connected to the tap terminal 213 (0V), the potential differences are 7V, 6V, and 4V, respectively. Alternatively, for example, if the first tap terminal 214 on the output side is connected to the tap terminal 210 (7V) and the second tap terminal 215 on the output side is connected to the tap terminal 211 (6V), the potential difference is 1V. Alternatively, for example, if the first tap terminal 214 on the output side is connected to the tap terminal 211 (6V) and the second tap terminal 215 on the output side is connected to the tap terminal 212 (4V), the potential difference is 2V. Alternatively, for example, if the first tap terminal 214 on the output side is connected to the tap terminal 210 (7V) and the second tap terminal 215 on the output side is connected to the tap terminal 212 (4V), the potential difference is 3V. The control unit 400 can adjust the degree of step-down by adjusting such a connection.
Similarly, the primary side circuit 200a-1 can be controlled by providing a plurality of input side tap terminals and a plurality of output side tap terminals.

  Alternatively, in either or both of the primary side circuit 200a-1 and the secondary side circuit 200a-2, a variable self-winding transformer capable of changing the number of turns of the coil is applied to form a continuously variable mechanism. it can.

  In the above-described example, the example in which the adjustment unit in the secondary side circuit 200a-2 is adjusted after the adjustment unit in the primary side circuit 200a-1 is adjusted has been described. However, the secondary side circuit 200a-2 is illustrated. After the adjustment unit is adjusted, the adjustment unit in the primary circuit 200a-1 can be adjusted.

  Moreover, in the above-mentioned example, the example provided with the adjustment part which adjusts the voltage after transformation in both the primary side circuit 200a-1 connected to the coil of the motor generator 100, and the secondary side circuit 200a-2. Although demonstrated, the adjustment part which adjusts the voltage after transformation | transformation should just be provided in at least one of the primary side circuit 200a-1 and the secondary side circuit 200a-2. For example, only the primary side circuit 200a-1 or only the secondary side circuit 200a-2 may be provided with a tap and stepped down by changing the number of turns.

In the above example, in step S1, the voltage value after stepping down by the transformer 200a is input as the target value. However, the target value may be a current value or the like, and represents a physical quantity of electricity. If it is.
In the above-described example, the example in which the control unit 400, which is a computer, automatically adjusts the degree of step-down by the transformation unit 200 in accordance with the measurement result by the measuring instrument 300 has been described. Information such as a measurement result by the device 300 may be output to a display, and the degree of step-down by the transformer 200 may be adjusted according to an instruction from a worker input according to the output information. Alternatively, an operator may adjust the transformer unit 200 directly.

<Second Embodiment>
Next, the dew condensation preventing apparatus 50 according to the second embodiment will be described with reference to the drawings. FIG. 5 is a diagram illustrating a configuration example of the transformer unit 200b that is the transformer unit 200 included in the dew condensation prevention device 50 according to the present embodiment.
The transformer 200b in the present embodiment is an AC / AC power converter, and the voltage is variable by the power converter. In this case, only the voltage may be changed without changing the frequency, or the frequency may be changed. In the case of alternating current, the reactance component is proportional to the frequency. Therefore, even if the voltage is the same, the higher the frequency, the smaller the flowing current.
Even in this case, the voltage applied to the motor generator 100 can be stepped down by the same control method as in the first embodiment.

<Third Embodiment>
Next, a dew condensation preventing apparatus 50 according to the third embodiment will be described with reference to the drawings. FIG. 6 is a diagram illustrating a configuration example of a transformer 200c that is the transformer 200 included in the dew condensation prevention device 50 according to the present embodiment.
The transformer 200c in the present embodiment is an AC / DC / AC power converter, and the voltage is variable by the power converter. The transformer 200c includes an AC / DC converter 220 that is a primary side circuit, a capacitor 221, and a DC / AC converter 222 that is a secondary side circuit.
Even in this case, the voltage applied to the motor generator 100 can be stepped down by the same control method as in the first embodiment.

  Note that a program for realizing the function of the processing unit in the present invention is recorded on a computer-readable recording medium, and the program recorded on the recording medium is read into a computer system and executed to prevent condensation. May be. Here, the “computer system” includes an OS and hardware such as peripheral devices. Further, the “computer system” may include a plurality of computer devices connected via a network including a communication line such as the Internet, WAN, LAN, and dedicated line. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” holds a program for a certain period of time, such as a volatile memory (RAM) inside a computer system that becomes a server or a client when the program is transmitted via a network. Including things. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, what is called a difference file (difference program) may be sufficient.

  In addition, some or all of the functions described above may be realized as an integrated circuit such as an LSI (Large Scale Integration). Each function described above may be individually made into a processor, or a part or all of them may be integrated into a processor. Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. Further, in the case where an integrated circuit technology that replaces LSI appears due to progress in semiconductor technology, an integrated circuit based on the technology may be used.

  DESCRIPTION OF SYMBOLS 1 ... Terminal 2 ... Switch 3 ... Fuse 4 ... Terminal 5 ... Terminal 6 ... Switch 7 ... Fuse 8 ... Terminal 9 ... Terminal 10 ... Terminal 11 ... Switch 12 ... Switch 13 ... Switch 50 ... Condensation prevention device 100 ... Motor generator 200 ... Transformer unit 200a ... Transformer unit 200a-1 ... Primary side circuit 200a-2 ... Secondary side circuit 200b ... Transformer unit 200c ... Transformer unit 201 ... Tap terminal 202 ... Tap terminal 203 ... Tap terminal 204 ... Tap terminal 205 ... Tap terminal 206 ... Tap terminal 207 ... Tap terminal 208 ... Tap terminal 300 ... Measuring instrument 400 ... Control unit

Claims (9)

A dew condensation prevention device for preventing dew condensation of a rotating machine having a coil connected to an AC power source ,
Said connected rotary machine and in parallel, the rotating machine is configured to be supplied a transformer the voltage steps down to a predetermined voltage of the AC power to the AC power source,
A measuring unit for measuring an electrical physical quantity between the transformer and the rotating machine;
A control unit that controls the degree of step-down in the transformer based on the electrical physical quantity measured by the measurement unit;
Condensation prevention device. 2. The dew condensation prevention device according to claim 1, wherein the control unit controls the transformation unit so that the degree of the step-down changes so that the electrophysical quantity input as an initial value falls within a predetermined range. . The transformer is a transformer including a primary side circuit and a secondary side circuit,
Each of the primary side circuit and the secondary side circuit is configured to be capable of switching the primary side voltage and the secondary side voltage of the transformer unit in stages by providing taps at different positions of the winding. And
The dew condensation prevention device according to claim 1 or 2, wherein the control unit controls the degree of step-down by switching the tap in at least one of the primary side circuit and the secondary side circuit.   The dew condensation prevention device according to claim 3, wherein the control unit switches the tap of the primary side circuit after switching the tap of the secondary side circuit.   The dew condensation prevention device according to any one of claims 1 to 4, wherein the rotating machine is a motor generator in a supercharger with a motor generator of a ship. A rotary machine having a coil connected to an AC power source, which is connected rotary machine and in parallel, can be supplied to the rotating machine by lowering the voltage of the AC power supply to a predetermined voltage transformer to the AC power source A dew condensation preventing method for preventing dew condensation of the rotating machine using a part,
A measuring step of measuring an electrical physical quantity between the transformer and the rotating machine;
A control step of controlling the degree of step-down in the transformer based on the measured electrical physical quantity;
Condensation prevention method comprising: The dew condensation prevention method according to claim 6, wherein in the control step , the transformer is controlled such that the degree of step-down changes until the electrophysical quantity input as an initial value falls within a predetermined range. The transformer unit includes a primary side circuit and a secondary side circuit that are capable of switching the primary side voltage and the secondary side voltage of the transformer unit in stages by providing taps at different positions of the winding,
Each of the primary side circuit and the secondary side circuit is configured to be capable of switching the primary side voltage and the secondary side voltage of the transformer unit in stages by providing taps at different positions of the winding. And
The dew condensation prevention method according to claim 6 or 7, wherein, in the control step , the degree of step-down is controlled by performing a switching operation on the tap in at least one of the primary side circuit and the secondary side circuit.   The dew condensation prevention method according to claim 8, wherein, in the control step, the tap of the primary circuit is switched after the tap of the secondary circuit is switched.

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