Flanged Big Current Transformer Bushing Full Range: BLFW / BDFW 12~40.5kV, 100~5000A, 55 Specifications at a Glance

Product Overview

This page presents the full range of XD flanged big current transformer bushings: four voltage classes, two structure types, 55 specifications. The bushing features brown porcelain sheds with an integral drilled mounting flange that mounts directly onto the transformer tank cover or side wall — no separate flange seat is required. Brass flag terminals are graded by current: 300A uses a 4-Φ10.5 flag, 400~600A a 4-Φ12.5 flag, 800~1200A a 4-Φ14.5 flag, 1600~3150A a 4-Φ16.5 flag (or 8-Φ14 equally distributed), and 4000~5000A a heavy 2-Φ18 flag.

Two structure types: ① BLFW cable type — the cable passes through the central tube (suffix L); ② BDFW threaded type — the conductor rod carries a bottom thread and is clamped from inside the tank with a nut (suffix D). Some BDFW ratings are further offered in standard-creepage (D0xx) and reinforced-creepage (D00xx) versions with taller sheds.

Four voltage classes: 12kV (300~600A, creepage 380mm), 24kV (300~5000A, creepage 744mm), 40.5kV (100~5000A, creepage 1260 / 1600mm). Bushing flange sizes: Φ148/Φ170 (12kV), Φ210/Φ250 (24kV), Φ260/Φ300 (40.5kV), mounting holes 8-Φ14 equally distributed. The mating welding flange on the transformer oil tank (Φ300~Φ120 series, 8-M12×15 or 8-M12 equally distributed) is to be provided by the user.

Model naming: BLFW / BDFW - Voltage / Current (e.g. BDFW-24/3150). Code format: XD.FLTG.voltage.Lxx / Dxx / D00xx. All dimensions listed are for conventional products; shaped specifications can be customized, and the bushing height can be freely selected according to customer requirements. Standard sealing material is nitrile rubber or acrylate rubber; fluorine rubber is available on request.

Models & Specifications

Table 1 | BLFW / BDFW-12kV flanged bushings (300~600A, 6 specifications)

※ Dimensions in mm. BLFW cable type per Figure 1, BDFW threaded type per Figure 2. Blank h2 (BLFW rows) and blank d2 (BDFW rows) are as printed in the original catalogue (structural difference). Bushing flange Φ148/Φ170, 4-Φ12.5 equally distributed. 2L2S = 2 large + 2 small sheds.

Table 2 | BLFW-24kV flanged cable-type bushings (300~1200A, 6 specifications)

※ Bushing flange 4 large + 1 small holes, Φ210/Φ250, 8-Φ14 equally distributed; tank welding flange Φ250/Φ210/Φ186/Φ136/Φ120, 8-M12×15 equally distributed (to be provided by the user).

Table 3 | BDFW-24kV flanged threaded-type bushings (300~3150A, 9 specifications)

※ The t1 column is filled only for 1600A and above (14/14/16); it is blank in the original catalogue for 300~1200A. Terminal plates 95~100 wide with 4-Φ16.5 holes for 1600A+.

Table 4 | BDFW-24kV flanged threaded-type big-current bushings (800~5000A, 9 specifications, suffix D10~D18)

※ This table is the deepened 24kV big-current version (h1=350; d1/d2/d3 one size larger than Table 3). Two rows exist for the 4000A rating (D16/D17, different H) as printed in the original catalogue. 4000~5000A use the heavy 2-Φ18 flag (8-Φ18 terminal plate).

Table 5 | BLFW-40.5kV flanged cable-type bushings (100~1200A, 7 specifications)

※ The 100~600A and 800~1200A groups use different flange diameters (210 / 250), with correspondingly larger d3, d4 and t. In the original catalogue the shed column of row L07 is printed "7L S" and the "6S" appears to be missing — to be confirmed with the engineering department.

Table 6 | BDFW-40.5kV flanged threaded-type big-current bushings (800~5000A, 18 specifications: standard creepage D01~D09 + reinforced creepage D001~D009)

※ D01~D09: standard creepage version (7L6S sheds, creepage 1260mm). D001~D009: reinforced creepage version (10L9S sheds, h1 deepened from 485 to 595, creepage 1600mm); all other dimensions are identical in both versions. Bushing flange Φ260/Φ300, 8-Φ14 equally distributed; tank welding flange Φ300/Φ254/Φ194/Φ154/Φ120, 8-M12 equally distributed (to be provided by the user). 7L6S / 10L9S = number of large / small porcelain sheds.

Mounting & Accessories

① Mounting: the integral cast-iron flange mounts directly onto the drilled tank cover or side wall (holes 8-Φ14 equally distributed); the reinforcing welding flange inside the tank is to be provided by the user, sized per the notes above. ② Terminals: brass flags are supplied by current rating — 300A (4-Φ10.5), 400~600A (4-Φ12.5), 800~1200A (4-Φ14.5), 1600~3150A (4-Φ16.5 or 8-Φ14 equally distributed), 4000~5000A (2-Φ18); the bottom cable hole Φd2 or conductor thread Md matches the cable / lead size. ③ Sealing: nitrile or acrylate rubber gaskets as standard; fluorine rubber available for special oil/temperature requirements. ④ Customization: bushing height can be freely selected; non-standard holes, terminal plates and shed arrangements are all customizable.

Typical Applications

Why XD

Flanged big current bushings are produced in-house by Tianjin Xingda (XD): four voltage classes and 55 specifications with complete tooling and stable supply. Within each voltage class, cable type and threaded type run in parallel, and standard or reinforced creepage can be selected; height, terminals and hole patterns are all customizable to customer drawings. This series is produced in the same factory as the five porcelain standard lines (GB BD/BJ, ANSI, NBR, DIN, EN) and the dry epoxy-resin bushings, so HV and LV bushings for all types of oil-immersed transformers can be sourced in one order. Gaskets are supplied with each bushing for direct assembly on the tank opening.