Expansion of line-up of stand-alone gas-insulated voltage transformers
for power plants and split-type transformers for outdoor use

A stand-alone gas-insulated instrument transformer is proposed as a measuring instrument to be assembled in a limited space of power generation equipment.

Murakami:Originally, we made a gas-insulated grounding type instrument transformer for gas-insulated switchgear of up to 0.5 million volts. Based on this technology, the insulators (devices that insulate between the electric wires and the supporting posts) were stacked toward the top to meet the need for space-saving equipment that can additionally be installed independently in existing equipment. They were designed into a tower shape. The insulator of the instrument transformer is 3.5m in size, so adding the main body of the instrument transformer is about 5m as a whole. A long insulator is absolutely necessary for high voltage insulation. This time, we have incorporated a newly developed high-precision instrument transformer, especially for weighing.

In the past, TAKAOKA TOKO did not have a track record of providing such a single-installation type gas insulated voltage transformer, but by developing instrument transformers for voltages from 110,000 to 275,000 V, the product lineup has increased. We believe it is our strength to have a product lineup ranging from low pressure to ultra-high pressure using solid, liquid, and gaseous insulators. In the future, we intend to propose and develop optimal delivery methods while meeting the needs of our customers.

It is mandatory to install measuring devices at all power plants by around 2023, and until then, development will continue to meet the needs of customers. After that, periodic updates are started to maintain the accuracy of the measuring instruments, so the instruments are designed to be installed and removed as easily as possible.

Murakami studied machinery and materials at the university and was interested in designing and joined the company in 2007. Now, when he sees the devices he designed being actually used by customers, he says that he has a sense of reality and a sense of rewarding. Murakami also has some thoughts about a low-carbon society. It is to make products as small as possible and contribute even a little to low-carbon manufacturing. He also says he considers using environmentally friendly insulators.

Redevelopment of existing products based on Measurement Act
In addition, high-precision, high-current cables are also supported.

Kobayashi:Outdoor split type current transformer existed in TAKAOKA TOKO’s lineup before the separation of power generation and transmission. However, it was for a protective circuit, and was used as a device to detect a large current, such as a short-circuit current, when it flowed. We have improved the accuracy so that it can be used for measurement in conjunction with the separation of electricity generation and transmission, and we have reconsidered the design so that it can be tested based on the standards set by the Measurement Act set by the government.

In a household, electric power consumption is measured by a single meter. However, if the meter is used to measure it at a high voltage such as that handled at a substation, the meter may be damaged. For this reason, we are converting to a level that can be measured. However, if the accuracy of the conversion ratio is poor, the measured value will change significantly. Therefore, we are creating a device with high conversion accuracy.

In addition, we have newly developed a larger one to handle thick cables, which cannot be handled by conventional split type current transformers. Originally, the current transformer must be connected only after the cable has been disconnected. However, this split-type current transformer allows the current transformer to be installed later on the existing cable. This is a great advantage in terms of efficiency and cost.

There were many times when we struggled. The most important point is whether the accuracy measured at the plant is reproduced when installing on-site. If the divided body is combined on-site, the accuracy will change if the combination makes a slight shift. Therefore, it is designed to minimize misalignment even if anyone combines it. Then, after installation, it is structured so that it cannot be disassembled with a "sealing cover" to prevent unauthorized modification. If the "sealing cover" is opened, it cannot be used as a measuring instrument. The moment this is safely sealed, I feel relieved. Another feature of this product is that it contributes to noncombustibility. Insulators can be solid, liquid, or gaseous, but this product employs nonflammable epoxy resin for solid insulation.

Kobayashi studied power system engineering in the electrical department in college. He joined TAKAOKA TOKO with the desire to do important work that supports society. He says that when he gives instructions on how to install split current transformers, he feels a sense of "supporting the infrastructure." His future dream is to realize decarbonization in design. With the conventional method of making and verifying many prototypes, a large amount of CO2 is generated at the prototype stage. To suppress this, we are replacing prototypes with computer-based simulations and reducing the number of prototypes.

Work to support electricity, an important social infrastructure. We continuously make trial and error every day to keep such infrastructure protected firmly. While clearing the challenges of a low-carbon society for the future, the two engineers are working hard today with a sense of satisfaction.