3EK8 Surge Arresters according to IEC 60099-4 — Mini-Catalog Data Sheet

Overview

The 3EK8 is a medium-voltage surge arrester family qualified to the IEC 60099-4 standard. This data sheet (a spread from the medium-voltage surge arrester mini-catalog) covers the full IEC-rated line-up: 15 catalog variants from 3.0 kV to 36 kV rated voltage, all sharing a 10 kA nominal discharge current, a charge transfer rating Qrs of 0.4 C, a thermal charge transfer rating Qth of 1.1 C, and a rated short-circuit current of 20 kA.

Each variant is defined by its rated voltage, continuous operating voltage, and housing type (designated by a letter in the type code, e.g. P, Q, R, S, T, V, W, X), which sets the height, creepage distance, insulation withstand values and permissible mechanical loads. Two housing options exist at 15 kV (153 mm and 180 mm height) and at 36 kV (332 mm and 390 mm height, with flashover distances of 344 mm and 402 mm respectively), giving extra creepage or flashover margin where needed.

Electrical characteristics

The table below reproduces the electrical ratings for all 3EK8 IEC variants. Residual voltages are maximum values at the stated discharge current and impulse shape. All variants share In = 10 kA, Qrs = 0.4 C and Qth = 1.1 C; the designation is DH throughout.

Mechanical characteristics

Mechanical and insulation data per variant: height H, creepage distance, housing insulation withstand voltages (lightning impulse 1.2/50 µs and power-frequency 1 min wet), specified short-term load (SSL) and specified long-term load (SLL) — each given for the arrester alone and with insulating bracket — approximate weight without accessories, flashover distance, and the required insulating bracket size. Rated short-circuit current Is is 20 kA for all variants.

How to order — type code

The order code is built from the family, rated voltage, standard, housing and shed configuration. Worked example 3EK8 360-1CW4: '3EK8' identifies the medium-voltage surge arrester family; '360' is the rated voltage (36 kV); '1C' denotes the IEC version; the letter (here 'W') selects the housing type (W corresponds to H = 332 mm); '4' means alternating sheds. A code without the -Z suffix ships with the standard M12 internal thread terminals.

Accessories are appended after a -Z suffix. Example: 3EK8 360-1CW4-Z M50 P50 M81, where M50 is a bolt M12x53 for the line terminal (M), P50 is a bolt M12x53 for the ground terminal (P), and M81 is a bird protection cap.

Dimensions

The dimensional drawing shows the 3EK8 IEC silicone-housed arrester: overall height H (per the mechanical table), shed diameter Ø 104 mm, M12 threaded connections at both the top (line) and bottom (ground) ends, each with a 20 mm thread engagement depth.

Figures & drawings

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