KYN61-40.5 Type Switchgear

Just as Cabinet 28 is the abbreviation for KYN28-12 air insulated 12kV switchgear, Cabinet 61 is KYN61-40.5 air insulated 40.5kV switchgear.

KYN - Industry standard model rules for serial numbers, K metal armor, Y detachable, N for indoor use.

In the 1990s, small-scale handcart style 40.5kV switchgear was introduced by foreign-funded enterprises such as Schneider, ABB, AREVA, TAMCO, etc. Among them, floor standing circuit breaker switchgear was the main type, with a width of generally 1.2 meters, and the most typical ones were ZS3.2 and VH3 switchgear.

With the increasing demand for 40.5kV switchgear in urban power grids and industrial users, the industry has invested in product research and development. Xigao Institute has led industry enterprises to jointly develop the KYN61 switchgear, which is equipped with circuit breaker ZN85 and grounding switch JN22.

KYN61 can be said to be the larger ZS3.2, with larger width, depth, and height. The contact box form is consistent, but the depth and height have been increased.

The design of KYN61 is technologically advanced and highly reliable compared to  domestic products such as KYN58 of the same period.

40.5KV switchgear is a miniaturized and withdrawable product that emerged in the late 1990s. In the early days, advanced circuit breakers and switchgear were introduced from abroad, such as Eaton Westinghouse's 405W-VACW and Merlin Gerin's CEI circuit breaker. These products are small in size and have high reliability, but their voltage level is 36kV (70kV power frequency withstand voltage, 170kV lightning impulse) according to foreign standards, which cannot meet the requirements of the national standard of 40.5kV (95kV power frequency withstand voltage, 185kV lightning impulse). By strengthening insulation and other designs, measures are taken to supplement where necessary to meet the requirements.

The design of 40.5kV switchgear is mostly based on 12kV, such as increasing the size and climbing distance of the contact box, without electric field analysis and actual use verification. These products have insulation problems after one or two years of use, and have to replace the contact box, or even replace the contact box mounting board from metal to insulation board to solve the problem.

The design of KYN61 fundamentally solves the problem of unreliable switchgear mentioned above. The cabinet is 1.4 meters wide with a phase spacing of 300/350mm. It is equipped with an ABB type contact box, and the grounding steel plate supports the contact arm to maintain a large electrical distance, further deepening the contact box to form a larger creepage distance. The rectangular busbar processing and installation are simpler, and the main busbar is arranged in a cross shape with a large spatial distance.

Many 40.5kV grounding switches extend the moving blade on the basis of 12kV, using high insulators to support the static contacts to ensure that the distance between the static contacts and the ground is greater than 300mm. This structure does not change the spring mechanism. The extension of the moving blade increases the moment of inertia, and the insufficient work of the spring slows down the closing speed, making it impossible to close the short-circuit current.

KYN61 has newly designed the JN22 grounding switch, with an increased size and base. Three thickened compression springs are sufficient to ensure sufficient closing speed of the moving knife and meet the requirement of short-circuit closing twice. Due to the increased size of the spring, the operating force has significantly increased, and the standard 2/1 and 3/1 bevel gears cannot meet the small operating force requirements. Therefore, KYN61 has designed an operating mechanism with further increased transmission ratio, which meets the standard operating force requirement of less than 250N.

The earliest designed KYN61 still had excellent performance and high reliability. However, due to the increasing number of manufacturers and fierce price competition, many manufacturers did not follow the original design and adopted alternative grounding switches, making it impossible to guarantee product quality.