Medium-voltage surge arresters — Siemens Energy catalog (online edition)

Catalog scope and portfolio

Surge arresters protect electrical equipment — transformers, circuit-breakers, bushings, generators, motors, capacitors, traction vehicles and complete switchgear — against overvoltages from direct or nearby lightning strikes, electromagnetic pulses, electrostatic discharge and switching operations. The surge current is diverted through the arrester, in most cases to earth; effective protection requires different arrester types depending on the application.

Siemens Energy has designed and manufactured medium- and high-voltage surge arresters since 1925, from 3 kV up to 1,200 kV including HVDC and FACTS applications. Within medium voltage (up to 72.5 kV) the catalog covers: the 3EK distribution class (3EK7 up to 60 kV with very high mechanical performance, 3EK8 up to 36 kV) for transformers, circuit breakers, MV switchgear/panels and distribution lines; the 3EJ cage-design high-energy family (3EJ2/3EJ3/3EJ4 up to 54 kV plus the very-low-protection-level 3EJ0 and 3EJ9) for generators, motors, arc furnaces and arc furnace transformers, dry-type transformers, airfield lighting, cable sheath, capacitor banks and drive converters; the 3EP-G porcelain arrester for generator/motor protection with short-circuit capability up to 300 kA; and the 3EH4 plug-in arrester (connector sizes 2 and 3 per EN 50180/EN 50181, IP66) for encapsulated switchgear and transformers up to 52.5 kV operating voltage.

This online catalog edition also points buyers to the Siemens Energy Energy-Shop (shop.siemens-energy.com/transmission/en), where the arresters can be configured and ordered directly.

Main technical data according to IEEE C62.11 (selection matrix)

Under IEEE C62.11 all listed product lines carry a maximum rated (duty-cycle) voltage of 36 kV. The energy classes assigned per product line are tabulated below. Rated short-circuit currents: 3EK7 20 kA, 3EK8 21 kA, 3EJ2 50 kA, 3EJ3 65 kA, 3EJ4 50 kA. High current impulse is 100 kA for all lines. Indoor versions are available for 3EK7 and 3EJ4.

The companion IEC 60099-4 selection matrix (same catalog spread) assigns designations DH (In 10 kA, Qth 1.1 C, Qrs 0.4 or 0.5 C), DM (In 5 kA), and energy-rated designations SL (10 kA, Wth 5.0 kJ/kVr, Qrs 1.2 C), SM (10 kA, 4.0 or 7.0 kJ/kVr, 2.0 C) and SH (20 kA, 4.0–18 kJ/kVr, Qrs 2.8–6.0 C) across the lines, with maximum IEC rated voltages 3EK7 60 kV, 3EK8 36 kV, 3EJ2/3EJ3/3EJ4 54 kV, 3EJ0 15 kV, 3EJ9 12 kV, 3EP-G 51 kV, 3EH4 52.5 kV.

3EK7 SL according to IEC 60099-4 (electrical characteristics)

The 3EK7 SL variant is the higher-energy version of the 3EK7 distribution arrester: designation SL, nominal discharge current In = 10 kA, charge transfer rating Qrs = 1.2 C, energy rating 4.5 kJ/kVr as printed in this table (the catalog's IEC selection matrix lists SL at Wth 5.0 kJ/kVr — both values transcribed verbatim from the source). Rated voltages 3–42 kV.

Mechanical characteristics for the SL series: housing heights 170–510 mm, creepage 372–1,595 mm, rated short-circuit current 20 kA throughout, lightning impulse withstand 104–302 kV, power-frequency withstand (wet) 49–140 kV, specified short-term load 980–2,940 N (arrester only), weights 1.5–5.4 kg.

3EK7 specifications according to IEEE C62.11 (electrical characteristics)

IEEE C62.11 ratings for the 3EK7: energy class B, lightning impulse classifying current In = 10 kA, single impulse charge transfer withstand rating 0.6 C, switching surge energy rating 4.5 kJ/kVMCOV. Each duty-cycle voltage is offered in two builds — order code '-3A…' (IEEE heavy-duty classification) and '-4A…' — with different protective levels and housings. Discharge voltages are crest values (kV cr).

Mechanical characteristics (imperial units in the source): heights 6.7–20.1 inches, leakage distance 14.6–62.8 inches, rated short-circuit current 20 kA, recommended minimum clearances 4–10 inches to ground and 6–15 inches between phases, maximum design cantilever load 123–370 lbf (arrester only), weights 2.8–8.9 lbs.

Ordering example 3EK7 360-3AH4: 3 = IEEE classification heavy duty, A = IEEE, H = housing type (H = 400 mm), 4 = alternating sheds; accessories are appended after '-Z' (e.g. M11 line clamp, P12 NEMA insulating bracket, M81 bird protection cap).

3EK7 indoor version specifications according to IEC 60099-4 (electrical characteristics)

The 3EK7 indoor version is a shedless cage-design arrester (order suffix '0' = shedless instead of '4' = alternating sheds) with identical residual voltages to the outdoor DH series: designation DH, In = 10 kA, Qrs = 0.5 C, Qth = 1.1 C, rated voltages 3–60 kV.

Mechanical characteristics: heights 170–470 mm, creepage 162–456 mm (indoor housings need far less creepage than outdoor), rated short-circuit current 20 kA, lightning impulse withstand 93–263 kV, power-frequency withstand (dry) 51–145 kV, weights 1.1–4.4 kg, flashover distance 161–455 mm. The catalog additionally tabulates a 3EK7 SL indoor series (3–42 kV) and a 3EK7 indoor IEEE series (duty-cycle voltages 3–36 kV); those tables follow the same pattern and are not reproduced here.

3EK8 HD according to IEEE C62.11 (electrical characteristics)

The 3EK8 heavy-duty (HD) wrap-design distribution arrester per IEEE C62.11: energy class A, lightning impulse classifying current 10 kA, single-impulse charge transfer rating Qrs = 0.4 C, switching surge energy rating 3.0 kJ/kVMCOV. Duty-cycle voltages 3–36 kV. Discharge voltages are crest values.

Mechanical characteristics (imperial): heights 3.2–12.7 inches, leakage distance 7.1–36.6 inches, rated short-circuit current 20 kA, recommended minimum clearances 3.0–12.8 inches (ph-gnd) and 4.3–16.3 inches (ph-ph), MDCL 98–384 lbf (arrester only), weights 2.3–6.9 lbs.

3EK8 RP (riser pole) according to IEEE C62.11 (electrical characteristics)

The 3EK8 RP riser-pole series offers lower protective levels than the HD series for cable-riser applications: lightning impulse classifying current 10 kA, single-impulse charge transfer rating Qrs = 0.4 C, switching surge energy rating 3.0 kJ/kVMCOV, duty-cycle voltages 3–27 kV (order code '-4A…'). No energy class column is printed for the RP series in the source.

Mechanical characteristics (imperial): heights 5.2–12.7 inches, leakage distance 13.0–36.6 inches, rated short-circuit current 20 kA, clearances 3.0–10.8 inches (ph-gnd) / 4.3–13.0 inches (ph-ph), MDCL 98–237 lbf, weights 2.9–6.4 lbs.

3EJ3 specifications according to IEC 60099-4 (electrical characteristics)

The 3EJ3 cage-design arrester offers high energy discharge capability at a low protection level and the silicone family's highest rated short-circuit current, 65 kA. Designation SH, In = 20 kA; two energy builds are offered at most rated voltages: Qrs = 2.8 C with Wth = 10.0 kJ/kVr (order code '…4 1 - 4') and Qrs = 3.6 C with Wth = 14.0 kJ/kVr (order code '…5 1 - 4'). Rated voltages span 1.4–54 kV, including sub-3 kV types unique to this line.

Mechanical characteristics: heights 172–498 mm, creepage 390–1,800 mm, rated short-circuit current 65 kA throughout, lightning impulse withstand 105–290 kV, power-frequency withstand (wet) 50–135 kV, specified short-term load 3,010–8,720 N, weights 5.0–18.5 kg, flashover distance 182–501 mm. An IEEE C62.11 companion table (energy classes G at 13 kJ/kVMCOV and J at 18 kJ/kVMCOV) covers duty-cycle voltages up to 36 kV.

3EJ0 specifications according to IEC 60099-4 (electrical characteristics)

The 3EJ0 provides a very low protection level for switching-overvoltage protection, normally in cable systems up to 15 kV. Designation DM, nominal discharge current In = 5 kA, Qrs = 0.5 C, Qth = 1.1 C, thermal energy rating Wth = 1.0 kJ/kVr. Note the different residual-voltage impulse set for this line: 30/60 µs at 125 A, 250 A, 500 A and 1 kA, plus 8/20 µs at 5 kA and 10 kA.

Mechanical characteristics (shedless indoor housings, order suffix '-0'): heights 170–200 mm, creepage 162–191 mm, rated short-circuit current 20 kA, lightning impulse withstand 93–110 kV, power-frequency withstand (wet) 51–60 kV, weights 0.5–1.2 kg. Ordering example 3EJ0 007-2CB71-0: B = housing type (H = 170 mm), 7 = energy class Wth = 1 kJ/kVr, 1 = 1 unit, -0 = shedless.

3EJ9 specifications according to IEC 60099-4 (electrical characteristics)

The 3EJ9 serves station service systems of power stations and extensive cable systems, combining a very low protection level with higher energy absorption than the 3EJ0. Two designations are offered: SM (In 10 kA, Qrs 2.0 C, Wth 4.0 kJ/kVr) and SH (In 20 kA, Qrs 6.0 C, Wth 4.0 kJ/kVr). The '-4A' suffix denotes the alternating-shed outdoor build offered in exchange for the legacy 3EF3-0; '-4B' is the higher-energy SH build. Residual voltages use the 30/60 µs 125/250/500 A/1 kA plus 8/20 µs 5/10 kA impulse set.

An indoor version (types 3EJ9 007-2CB71-0B and 3EJ9 012-0CC71-0B, designation SH) carries electrical values identical to the corresponding '-4B' outdoor types. Mechanical characteristics, outdoor series: heights 166–232 mm, creepage 430–660 mm, rated short-circuit current 50 kA, lightning impulse withstand 100–140 kV, specified short-term load 4,730–10,630 N, weights 3.3–10.9 kg; indoor series: heights 188/232 mm, creepage 220/260 mm, weights 7.8/9.6 kg.

3EP-G porcelain surge arresters — specifications according to IEC 60099-4

The 3EP-G porcelain-housed arrester protects generators and motors that require very high short-circuit current capability — up to 300 kA. Directional pressure relief devices at top and bottom let the arc escape in an overload without internal pressure buildup or ejection of parts. Nonporous sulfur cement (instead of corrosive Portland cement) bonds and protects the MO resistors against aging, and an FRP-rod cage holds the resistor column tightly in place.

All types share designation values In = 10 kA, Qrs = 2.0 C, Wth = 7.0 kJ/kVr and rated short-circuit current Is = 300 kA. Mechanical characteristics are identical across the series: height 665 mm, creepage 1,035 mm, lightning impulse withstand 206 kV, power-frequency withstand (wet) 78 kV, specified short-term load 51,120 N, specified long-term load 20,450 N, flashover distance 350 mm, weights 80.1–84.1 kg. Ordering suffix '-Z K83 P2G R2G' denotes enhanced 300 kA short-circuit performance, 13 mm terminal plate and insulated mounting; packing: single 80×80×130 mm, triple 150×80×130 mm.

Ordering-code system, accessories and packing

3EK ordering codes follow the pattern family + rated-voltage digits + build code, e.g. 3EK7 360-4CH4: 4 = LD class 1 (5 = LD class 2), C = IEC (A = IEEE), H = housing type (H = 400 mm), final digit 4 = alternating sheds (0 = shedless indoor). Accessories are appended after '-Z', e.g. 3EK7 360-4CH4-Z M11 P12 M81 = line clamp + NEMA insulating bracket + bird protection cap. 3EK line-terminal spare parts include the M11 line clamp Ø8–18 mm (3EX4 063-0A for 3/8-inch thread, 3EX4 063-0C for M12).

3EJ accessories: L-bracket (3EX4 500-1L), flat DIN/NEMA terminal 402×502 mm (3EX4 500-1X); insulated mountings Ø190–260 mm / 170×170 / 200×200 / 310×310 mm (3EX4 500-2A/-2B/-2C/-2D) and grounded mountings in the same sizes (3EX4 500-3A/-3B/-3C/-3D — the 170×170 grounded mounting is printed 'EX4 500-3B' in the source). Packing dimensions 3EJ: 3EJ0 housing B 270×220×142 mm, housing C 300×220×142 mm; 3EJ2/3EJ3/3EJ4/3EJ9 all housings 290×280×560 mm.

The glossary defines the key rating symbols used throughout: Uc/MCOV (permissible continuous power-frequency voltage), Ur (rated / duty-cycle voltage, reference for operating characteristics, applied 10 s or 100 s in the operating duty test), Us (highest system voltage), In (nominal discharge / lightning impulse classifying current), Is (rated short-circuit current withstood without violent housing shattering), residual/discharge voltage and the lightning (8/20 µs), switching (30/60 µs) and steep-current (1/2 µs) protective levels, creepage/leakage distance, specific creepage distance (mm/kV of Us), and temporary overvoltage (TOV).

Figures & drawings

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