JP5923971B2 - Transformer for movement - Google Patents

Description

  The present invention relates to a moving transformer, and more particularly, to a moving transformer that can be easily transported by reducing the size and weight by improving the cooling of the transformer body.

  In general, mobile transformers are used for emergency when inspecting transformers used in power facilities at power plants and substations, when they break down due to long-term use, or when they break down due to a disaster. . The moving transformer moves from the storage location to the power facility and is connected to the power system instead of the existing transformer, so that the power system can be operated immediately.

  The transformer for transportation is mounted on a low-floor trailer towed by a truck or a loading platform extending behind the truck driver's seat, so there are restrictions on width and height, and weight is also possible It is required to be as light as possible. For this reason, it has been proposed that the winding is made compact and the width of the transformer main body is made shorter than the vehicle width of the transporting vehicle to form a moving transformer, and that the transporting vehicle is easily and safely transported (for example, Patent Document 1).

  In addition, when using a low-floor trailer that is towed at the truck driver's seat, a common base that has a beam part that contacts the low floor surface of the trailer and that avoids the rear wheel of the low-floor trailer is used. The equipment is loaded on the common base low floor surface, and the auxiliary equipment is loaded on the beam, and the transformer and auxiliary equipment are integrated to enable transportation with a general-purpose low floor trailer. It has also been proposed to facilitate installation on site (see, for example, Patent Document 2).

  Since it is difficult to reduce the weight of the low-floor trailer towed at the truck driver's seat, it is desirable to make the moving transformer as light as possible. The main measures to reduce the weight of mobile transformers are, for example, use aluminum that is lighter than iron in the tank, and reduce the amount of insulating oil enclosed inside the tank by making it suitable for the transformer contents. Insulating materials with high heat resistance that can be used even at high temperatures are used in the transformer. The temperature rises, but the current density is increased to reduce the windings and the number of cooling devices.

By the way, in general, a transformer uses mineral oil as an insulating oil to be enclosed in a tank. Recently, however, a plant raw material palm palm oil (palm palm fatty acid ester, PFAE = Palm Fatty Acid Ester) is encapsulated in place of mineral oil. It has been proposed. Transformers using palm palm oil can reduce CO ₂ emissions significantly compared to transformers using mineral oil, making them suitable for measures against environmental impacts and reducing transformer installation area by improving cooling performance Can be made more compact than in the past.

JP 2004-221333 A JP 2005-348490 A

  In the moving transformers of Patent Documents 1 and 2 described above, as the insulating oil sealed in the tank, mineral oil having a low kinematic viscosity suitable for cooling the windings and the iron core constituting the transformer is used. However, when mineral oil is used for the insulation oil of the transformer, each manufacturer manufactures the coil in order to prevent the static electricity phenomenon caused by the flow of the solid surface such as insulating paper used for the winding, that is, the flow charge. In addition, the oil flow velocity in the oil passages above and below the winding is limited to a maximum value as known in various documents.

  Although it is desirable that the transformer for movement is small and lightweight, the mineral oil is limited to a flow rate that does not cause flow electrification. In addition, when using mineral oil in a transfer transformer tank, the above-described current means almost limit the weight reduction. In particular, in a truck-mounted transfer transformer, since a weight reduction of about 100 kg is valuable, another means for reducing the weight is required to overcome the limit of the weight reduction.

  An object of the present invention is to provide a moving transformer that can improve cooling performance and can be reduced in weight.

The transfer transformer according to the present invention is configured by placing the transformer contents in the tank and enclosing the insulating oil therein, and the cooler for cooling the insulating oil on a movable loading platform, When a transformer and the cooler are connected by an oil feeding pipe and an oil feeding pump for circulating insulating oil in the oil feeding pipe is provided, palm oil is used as the insulating oil, and the oil feeding pump is made of the palm palm oil. The maximum value Vmax of the flow velocity is 100 cm / s ≦ Vmax ≦ 500 cm / s , and it is characterized in that it is configured so as to ensure the oil flow of the palm palm oil in a turbulent flow region . Preferably, the oil feeding pump includes one or more oil feeding pumps provided in the oil feeding pipe.

  According to the transfer transformer of the present invention, palm oil that can suppress environmental load is used as the insulating oil, and palm oil that has a low kinematic viscosity at a much faster flow rate than that of mineral oil is transferred into the tank by an oil feed pump. Therefore, the cooling performance of the transformer can be improved. For this reason, since the current density of the winding can be increased by the amount that can cool the transformer contents, and the transformer contents can be made smaller, the weight of the entire moving transformer can be reduced.

It is a side view which shows one Example of the transformer for a movement of this invention. It is a schematic sectional drawing of the transformer for a movement of FIG. It is a figure which shows the trial calculation of the effect of a palm palm oil containing movement transformer. It is a graph which shows the relationship of the rate of the heat-transfer rate increase with respect to the flow velocity of FIG. Winding weight reduction, iron core weight reduction, winding and iron core weight reduction, oil pump weight increase, weight reduction effect by improving cooling performance, effect of palm palm oil being lower density than mineral oil for the flow velocity in FIG. It is a graph which shows the relationship of the weight reduction effect which combined both the effect by cooling performance improvement.

The present invention is a moving transformer in which a transformer in which a transformer is housed and an insulating oil is enclosed and a cooler that cools the insulating oil is placed on a movable carrier, and the transformer And the cooler are connected by an oil feed pipe, and an oil feed pump for circulating insulating oil through the oil feed pipe is provided. Palm oil is used as the insulating oil, and the oil pump has a maximum flow velocity Vmax of 100 cm / s ≦ Vmax ≦ 500 cm / s , and the oil flow of the palm palm oil is ensured in a turbulent flow region . It has what it can do.

  Hereinafter, the transfer transformer of the present invention will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, the transformer for movement according to the present invention is configured such that a transformer 10 and a cooler 20 for cooling insulating oil are placed on a loading platform 2 extending rearward from a truck driver's seat 1 so as to be movable. Yes.

  As shown in FIG. 2, the transformer 10 encloses a palm coconut oil 14 capable of accommodating the contents of the transformer including the iron core 12 and the winding 13 in the tank 11 and suppressing the environmental load as an insulating oil. In this example, the cooler 20 includes an air-cooled type that can sufficiently cool the palm palm oil 14.

  The transformer 10 and the cooler 20 are connected by an oil feeding pipe 15 connected to the upper and lower sides of the tank 11, and an oil feeding pump 16 that circulates palm palm oil 14 is provided in the oil feeding pipe 11. In the transfer transformer of the present invention, when palm palm oil 14 is used as the insulating oil sealed in the tank 11, the oil feed pump 16 provided in the oil feed pipe 11 has a flow rate described later that is much faster than the case of mineral oil. What can circulate the palm palm oil 14 from the cooler 20 in the tank 11 is used.

  The transformer 10 shown in FIG. 2 is an example in which a tap changer 17 is provided in a part of the tank 11, and oil entered from the lower part of the tank 11 is sufficiently utilized for cooling the winding 13. In order not to impair the cooling efficiency, an oil guide 18 for regulating the flow of oil is provided.

  Palm palm oil used as insulating oil has characteristics as shown in Table 1 in comparison with physical properties of mineral oil, that is, density is about 2% smaller, specific heat is about 8% larger, and kinematic viscosity is about 40% smaller. In addition, there are advantages that the relative dielectric constant is about 30% larger and the volume resistivity is three orders of magnitude smaller.

  In the case of mineral oil, the flow velocity v is limited by countermeasures against flow electrification, so the oil flow in the winding 13 is a Reynolds number Re = v × d / ν <1000 and is a laminar flow (where d is a hydraulic diameter). ). Since v × d is unchanged, when palm palm oil 14 is used, although the ratio of kinematic viscosity ν in Table 1 above 8.13 / 5.06 = 1.6 increases slightly at Re <1600, It is a laminar state. In addition, since palm palm oil 14 has a small volume resistivity, it is difficult to flow and charge, so it is possible to increase the Reynolds number Re by increasing the flow velocity v and use it in a turbulent flow region.

When the Sieder-Tate equation is used, Nussel number Nu of laminar heat transfer in the forced convection tube is Nu = 1.86 × (Re × Pr) ^Λ (1/3) × (d / L) ^Λ (1/3) × (μ / μ _W ) ^Λ 0.14 (length L, bulk average temperature and viscosity at wall temperature μ, μ _W ), and heat transfer coefficient α is α = Nu × λ / d∝ (V × ρ × c) ^Λ (1/3). From the ratio of (ρ × c) ^Λ (1/3) in Table 1, ((0.86 × 2.02) / (0.88 × 1.86)) ^Λ (1/3) = 1.02 When palm palm oil is used instead of mineral oil, an increase in heat transfer coefficient α (effect due to a difference in physical property values excluding the 1/3 power of flow velocity v) can hardly be expected.

Therefore, in the laminar basin, the heat transfer coefficient α is determined by the 1/3 power of the flow velocity v, and due to the characteristics of palm palm oil, it is possible to increase the flow velocity without being restricted by the flow charge flow velocity. Heat transfer coefficient α is almost unchanged (difference in oil type has little effect on heat transfer coefficient α, only by flow rate difference)
The Nusselt number Nu of the turbulent heat transfer in the forced convection tube can be expressed as Nu = 0.023 × Re ^Λ 0.8 × Pr ^Λ 0.4 using the Ditus-Boelter equation. The heat transfer coefficient α is given by α∝v ^Λ 0.8 × (ρ × c) ^Λ 0.4 × λ ^Λ 0.6 / ν ^Λ 0.4. The ratio of (ρ × c) ^Λ 0.4 × λ ^Λ 0.6 / ν ^Λ 0.4 in Table 1, ((0.86 × 2.02) / (0.88 × 1.86)) ^Λ 0 .4 × (1.26 / 1.23) ^Λ 0.6 / (5.06 / 8.13) From ^Λ 0.4 = 1.256, heat transfer coefficient when palm oil is used instead of mineral oil The rate of increase of α (effect due to the difference in physical property value excluding the 0.8th power of the flow velocity v) is 1.256 times.

  Therefore, in the turbulent region, the heat transfer coefficient α is determined by the 0.8th power of the flow velocity v, and due to the characteristics of palm palm oil, in addition to being not subject to flow charge flow velocity limitation, the heat transfer coefficient is higher than that of mineral oil at the same flow velocity. α is increased 1.256 times, and the temperature rise can be reduced to 80% when mineral oil is used at the same flow rate. However, it is necessary to consider the increase in the mass of the oil pump.

The above compares the difference in heat transfer coefficient due to the difference in oil type under the same flow rate, but under the same oil feed pump, palm palm oil, which has a lower kinematic viscosity than mineral oil, has a lower pressure loss and a higher flow rate. The heat transfer coefficient α is further increased. For example, in the case of laminar flow, when roughly evaluated by trial calculation of only pipe friction, the flow velocity is 8.13 / 5.06 = 1.6 times the inverse ratio of kinematic viscosity ν in Table 1, and the heat transfer coefficient α is 1.6 ^Λ. (1/3) = 1.17 times, and considering the presence of pressure loss other than pipe friction, it is considered that approximately 10% of the heat transfer coefficient of palm palm oil is larger than that of mineral oil.

  The present inventor examines the optimum flow velocity of the palm palm oil 14 from the trial calculation of the effect of the transformer for moving palm palm oil shown in FIG. 3, and the maximum value Vmax of the flow velocity is in a range of 100 cm / s ≦ Vmax ≦ 500 cm / s. Found out what is desirable. Note that the maximum value Vmax of the flow velocity here is the maximum value of the flow velocity in the winding 13 and the oil passage above and below the winding 13. In general, the flow rate is determined and analyzed. In an actual transformer, the flow rate in the oil feed pipe 15 is measured, and the maximum value of the flow rate in the winding 13 and the oil path above and below the winding 13 is taken into account in consideration of the pressure loss of each part. presume.

  The oil feed pump 16 that secures the maximum velocity Vmax of the palm palm oil 14 described above is provided with one unit in the oil feed pipe 11 in consideration of this increase in weight, or a plurality of units that can suppress the increase in weight are used. They can be used in parallel.

  FIG. 3 shows the result of trial calculation of the weight reduction effect when the pressure loss is assumed only by pipe friction and the maximum value Vmax of the flow velocity is used at 100 to 900 cm / s in the transformer for movement containing palm palm oil. . FIG. 4 shows the relationship between the results of the increase in the heat transfer coefficient, the increase in the current density, and the rate of reduction in the temperature rise with respect to the maximum value Vmax of the flow velocity, and FIG. 5 shows the relationship between the maximum velocity Vmax and the weight that can be reduced. ing. As is clear from these, when the maximum value Vmax of the flow velocity is in the range of 100 to 500 cm / s, the effect of weight reduction due to the use of low-density palm coconut oil and the improvement of the cooling performance of the windings may be set to a preferable value. it can.

  For example, if a truck-mounted transfer transformer is used with an oil volume of about 4000L, the weight will be reduced by several tens of kilograms or more when palm oil is used compared to mineral oil due to the difference in density. Can be planned. Further, since the current density of the winding can be increased by the amount of the improvement of the cooling performance, the content of the transformer composed of the iron core and the winding can be reduced, and similarly, the weight can be reduced by several tens of kg or more.

  In the above-described embodiment shown in FIG. 1, the transformer and the cooler are described as an example of a truck-mounted transfer transformer in which the transformer and the cooler are mounted on the loading platform extending rearward from the truck driver's seat. The present invention can be similarly applied to a trailer-loading type moving transformer that is placed on a loading platform of a trailer that is towed and moved in a seat portion.

DESCRIPTION OF SYMBOLS 2 ... Loading platform, 10 ... Transformer, 11 ... Tank, 12 ... Iron core, 13 ... Winding, 14 ... Palm coconut oil, 15 ... Oil feeding pipe, 16 ... Oil feeding pump, 20 ... Cooler.

Claims (2)

A transformer that contains the contents of the transformer in a tank and in which insulating oil is sealed, and a cooler that cools the insulating oil are placed on a movable carrier, and an oil feed pipe is provided between the transformer and the cooler. In the transfer transformer having an oil feed pump that is connected by the oil feed pipe and circulates the insulating oil in the oil feed pipe, the palm oil is used as the insulating oil, and the oil feed pump sets a maximum value Vmax of the flow rate of the palm palm oil to 1. It is 00cm / s <= Vmax <= 500cm / s, Comprising: The transformer for a movement characterized by including the thing which can ensure the oil flow of this palm palm oil in a turbulent flow area was comprised.   2. The moving transformer according to claim 1, wherein the oil feeding pump includes one or more oil feeding pumps provided in the oil feeding pipe.

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