Manual · DE/EN — Official Siemens operating instructions (Order No. 927 00210 174 E, Siemens AG 2000, Schaltwerk Hochspannung Berlin) for the 3AP1 FG outdoor SF6 self-compression circuit breaker for rated voltages up to 170 kV. The triple-pole breaker uses SF6 gas for insulation and arc quenching and has one common spring drive mechanism for all three poles, making it suitable for triple-pole auto-reclosing. The manual covers the full lifecycle: technical data (insulation ratings, electrical data, operating times, SF6 filling values), mechanical design (pole columns, interrupter unit, arc quenching, spring drive mechanism, control and gas monitoring), installation and commissioning (erection, coupling of operating mechanisms, SF6 filling, test switching, commissioning report), operation (SF6 pressure monitoring, lockouts, permissible number of interruptions), and maintenance (12-year routine inspection, 25-year major inspection, contact-system check, detailed work steps). Bilingual German-English original; the English column was used for this digitization.
These operating instructions apply to the type and version of the 3AP1 FG circuit breaker stated on the title page and familiarize operating personnel with its mechanical design, function, operation, erection and maintenance. All pressure values quoted are gauge values unless absolute pressure is expressly stated. The manual is organized into chapters General (0), Description (1), Installation and Commissioning (2), Operation (3) and Maintenance (4), with a chapter-section-subsection numbering scheme for precise references.
During operation, parts of the breaker are electrically live and under SF6 gas pressure. Pure SF6 is colourless, odourless, tasteless, non-toxic and non-flammable, and is safe with adequate oxygen in inhaled air. For transport and delivery the breaker poles are pre-filled with SF6 at 0.3–0.5 bar / 0.03–0.05 MPa / 4.5–7.5 psig. Non-observance of the warnings can result in death, severe personal injury and substantial property and environmental damage; the operator must keep safety accessories and the complete operating instructions available and adhere to the specified maintenance intervals.
The 3AP1 is a triple-pole outdoor self-compression circuit breaker using SF6 gas for both insulation and arc quenching. One spring drive mechanism is common to all three phases, so the breaker is suitable for triple-pole auto-reclosing. It conforms to IEC Publication 60056 and VDE 0670 Parts 101–108, and is designed for ambient temperatures from -20 °C to +40 °C. The data applying to an individual delivered breaker are stated on its rating plate and in the appended documentation.
For installation at altitudes above 1000 m, the dielectric strength of the external air insulation is corrected by a divisor ka = e^(m·(H-1000)/8150), with H the altitude in metres and m = 1 for power-frequency and lightning withstand voltage (and switching impulse between phases), m = 0.9 for switching impulse across the interrupter unit, and m = 0.75 for switching impulse to earth (from IEC 60694 05/96).
| Insulation rating as per IEC | Unit | 170 |
|---|---|---|
| Rated frequency | Hz | 50 |
| Rated power frequency withstand voltage (rms) — to earth | kV | 325 |
| — across the open circuit-breaker | kV | 325 |
| — between phases | kV | 325 |
| Rated lightning withstand voltage (1.2/50 µs) — to earth | kV | 750 |
| — across the open circuit-breaker | kV | 750 |
| — between phases | kV | 750 |
| Flashover distance — to earth | mm | 1500 |
| — across the open circuit-breaker | mm | 1400 |
| — between phases | mm | 1510 |
| Min. creepage distance — to earth (25 mm/kV) | mm | 4250 |
| — to earth (31 mm/kV) | mm | 5270 |
| — across the open circuit-breaker (25 mm/kV) | mm | 4250 |
| — across the open circuit-breaker (31 mm/kV) | mm | 5270 |
The headline electrical ratings at 170 kV are 50 Hz, 3150 A rated current, 40 kA rated short-circuit breaking current, transient recovery voltage under terminal fault conditions per IEC/VDE, 100 kA rated making current, 1 s rated short-circuit duration, and an operating sequence of O - 0,3 s - CO - 3 min - CO or CO - 15 s - CO.
Operating times are given for standard and quick tripping devices. The auxiliary switch is type 3SV 92 (rated 220/110/60/48 V DC, 10 A continuous; switching capacity 2.5/5/9/10 A resistive and 2/4/7/9 A ohm-inductive at time constant 20 ms). Data for trip coils, control voltage, SF6 pressure monitoring and the charging motor are enclosed in the breaker documentation; the anti-condensation heating of the operating mechanism unit draws approx. 115 W and must always be switched on. Breaker weights: see dimension drawing.
| Tripping device | Unit | standard | quick |
|---|---|---|---|
| Minimum command duration | ms | 80 | 80 |
| Closing time | ms | 55 ± 8 | 46 ± 8 |
| Opening time | ms | 30 ± 4 | 23 ± 3 |
| Arcing time | ms | ≤ 23 | ≤ 23 |
| Break time at | ms | ≤ 57 | ≤ 49 |
| Close-open-time | ms | 30 ± 10 | 30 ± 10 |
| Dead time | ms | ≥ 277 | ≥ 277 |
The SF6 filling curve and the density monitor operating values are temperature-dependent; the manual reproduces the filling curve (nominal density line), the 'Loss of SF6' signal line, the SF6 general lockout line and the liquefaction curve from -40 °C to +50 °C (Fig. 2 of section 1-0080). All monitoring values are gauge pressures at 20 °C.
| SF6 data (rated voltage 170 kV) | Unit | Value |
|---|---|---|
| Weight per breaker | kg | 12.3 |
| Volume per breaker | dm3 | 206.4 |
| Nominal pressure at 20 °C | bar / MPa | 8.0 / 0.8 |
| Filter material per pole | kg | 0.5 |
| Alarm "Loss of SF6" (at 20 °C) | bar | 7.2 |
| General lockout SF6 (at 20 °C) | bar | 7.0 |
| Minimum gas pressure for mechanical operating | bar | 3.0 |
The three identical pole columns rest on a common breaker base (11) with the operating mechanism unit (18) fastened to it. Each interrupter unit (22) is mounted on a post insulator (16) providing insulation to earth; the three pole columns are connected by piping to a single gas compartment whose SF6 density is monitored by a density monitor and whose pressure is indicated by a gauge. The switching movement is transmitted from the spring drive mechanism at earth potential via an operating linkage, the torque shaft and an operating rod of insulating material to the interrupter unit at high-voltage potential. The corner gear houses filter material that collects SF6 decomposition products and moisture.
Inside the gas-tight porcelain jacket, the main current path consists of the upper high-voltage terminal, the contact carrier, contact fingers arranged in a ring, the heat cylinder, the base and the lower terminal. Parallel to it runs the arcing current path formed by the pin in the contact carrier and the moving arcing contact (tube contact) in the heat cylinder, both made of materials with especially high erosion resistance. The tube contact, piston and heat cylinder are mechanically interconnected, coupled with the pull rod, and form the moving part of the interrupter; the rear of the piston carries a valve plate which together with the valve group makes up the compression unit for arc quenching.
On opening, the main contact (contact fingers and heat cylinder) opens first while the arcing contact (pin and tube contact) remains closed, commutating the current to the arcing contact. As the arcing contact then opens and draws an arc, the heat cylinder moves downward and compresses the quenching gas between cylinder and valve group; the gas is forced through the non-return valve into the heat cylinder and through the gap between moving arcing contact and arc-quenching nozzle, quenching the arc.
With large short-circuit currents, the quenching gas around the pin is heated by the arc's own energy and driven into the heat cylinder at high pressure; as the current passes through zero, the gas flows back through the nozzle and quenches the arc. The non-return valve in the heat cylinder prevents this high pressure from entering the compression chamber between piston and valve group.
Switching energy is stored in one closing spring common to all three poles and one opening spring, both located in the operating mechanism unit. Pole column B is driven directly via a corner gear and is connected to the corner gears of columns A and C by coupling rods. The closing spring is charged by the motor and charging gear via the charging shaft; a free-wheel decouples the gear once the shaft is latched by the closing latch. Actuating the CLOSE trip coil releases the closing latch: the discharging closing spring drives the cam plate, lever and operating shaft, closing the interrupter contacts and simultaneously charging the opening spring. The closing damper and backstop absorb residual energy and prevent backswing of the charging shaft.
The closing spring is completely recharged in less than 15 s, and a mechanical closing interlock prevents re-closing of the mechanism before an opening operation. Actuating the OPEN trip coil releases the opening latch and the opening spring separates the contacts via the connecting rod, operating mechanism rod and coupling linkage; the opening damper absorbs the motive energy and acts as end stop. In the closed position both springs are charged, so the breaker can perform O-C-O switching sequences.
The operating mechanism unit contains all components for operation, monitoring and control, arranged in function groups in a climate-proof, ventilated and heated cubicle of degree of protection IP 55. Circuit functions include a general SF6 lockout (blocks all switching at too-low SF6 pressure), a closing lockout while the closing spring is being charged, and an anti-pumping feature that prevents repeated open-close cycling under simultaneous ON and OFF commands. The breaker is equipped with an operating cycle counter, free auxiliary switch contacts for the customer, and anti-condensation heaters that must be in continuous operation.
The monitored gas compartment encompasses all three pole columns, each with a non-return valve, plus a density monitor B4, a pressure gauge, filling connection W1 and test connection W2. The density monitor compares the density of the SF6 in the compartment with a reference gas enclosed inside the monitor, both exposed to the same ambient temperature; it responds to pressure changes caused by leaks but ignores changes due to temperature. It is set at the works to the required limit density — resetting is neither necessary nor possible.
The breaker is delivered as pretested modular assemblies: the breaker frame with mechanism and control fully assembled, springs relaxed, pole columns pre-filled with SF6 to transport pressure, and SF6 gas supplied in cylinders. Crates can be stored outdoors on wooden planks under tarpaulins, with the anti-condensation heater energized during storage; after one year, Tectyl 506-treated surfaces need a second coating. For assembly, only the bolts supplied may be used (grade 8.8 or higher, minimum tensile strength 800 N/mm2, yield 640 N/mm2), with prescribed torques M6: 8 ± 1 Nm, M8: 20 ± 2 Nm, M10: 40 ± 4 Nm, M12: 70 ± 7 Nm, M16: 170 ± 20 Nm, and union nuts at 40 ± 4 Nm.
Erection proceeds by separating the shipping unit, craning the breaker base with mechanism onto the foundation pillars (8 bolts M16, levelled with a spirit level), leak-testing each pre-filled pole column via the non-return valve (an audible hiss confirms the priming filling), erecting pole column B (identified by the double lever on its corner gear) and then columns A and C, coupling the operating mechanism rods and coupling rods, and connecting one SF6 line per pole column (union nuts to 40 Nm). For transport of a fully assembled breaker the gas gauge pressure must not exceed 0.5 bar/0.05 MPa/7.3 psig and transport beams must be used against toppling.
After earthing the base and connecting high-voltage leads (contact surfaces steel-brushed bright and coated with acid-free vaseline; Kupal spacers with copper connectors) and control cables, the breaker is filled with SF6 from cylinders using filling device W 423 with a mandatory safety valve (operating pressure 8 bar/0.8 MPa/116 psig), observing the temperature-dependent filling curve; the filling tolerance is up to 0.3 bar over the nominal pressure curve. All new pipe joints must then be leak-tested with a leak detector. First mechanical test operations must be performed as remote-controlled safety switching operations with no persons within 60 m, never without gas filling (minimum 3.0 bar/0.3 MPa/44 psig); 5 close-open operations per pole are performed. Commissioning checks cover the anti-condensation heaters, all command and signalling paths, paintwork, and completion of the commissioning report to be returned to the manufacturer.
A breaker connected to high voltage may only be operated from the control room or from the local control cabinet; operating the trip coils directly bypasses the switchgear interlock and the SF6 interlocking. If SF6 pressure drops unduly, a 'Loss of SF6' signal is initiated and the breaker must be isolated and topped up to nominal pressure via flange W1 (thread M26 x 1.5 or M45 x 2); recurring signals require leak location and sealing, or notification of the nearest Siemens representative. Below the lockout density a general lockout blocks all further operation, and a mechanical reclosing lock-out in the mechanism prevents re-closing when the breaker pole is already closed. For test switching in the dead state, a minimum SF6 pressure of 3 bar/0.3 MPa/44 psig is required.
The permissible number of interruptions n depends on the breaking current I: type tests covered 10 000 mechanical operating cycles, and the diagram allows about 6000 operations up to roughly 4 kA falling to about 6 at the full 40 kA rating (per pole of a triple-pole breaker; three times the single-pole count applies, e.g. 18 single-pole openings at 40 kA). The remaining permissible interruptions are computed with a weighting factor k as nx = (6000 - Σ ni·ki)/kx; a worked example shows a breaker with 250 interruptions at 5 kA and 2 at 20 kA still has 13 interruptions at 30 kA available.
For irregularities the manual tabulates signal/lock-out, effect, possible causes and remedies: 'Loss of SF6' (signal only, leaks are generally slow) — locate fault, seal leak and top up to nominal pressure; general SF6 lockout (no switching possible) — treat as loss of SF6; closing lock-out longer than 15 s (closing spring not charged) — provide motor power supply or replace the defective motor. Work on the operating mechanism may only be done with opening and closing springs relaxed.
The 3AP1 FG is an environmentally compatible product; at end of life priority is given to material re-use (steel, copper, aluminium, PTFE, cast resin, glass-fibre-reinforced plastics, sealing rubbers, ceramics, greases). The synthetic hydraulic fluid (Anderol BDH 15) in the mechanism damper must be drained before disposal, SF6 must be drained/evacuated for reconditioning and re-use, and solid switching decomposition products in opened gas compartments require the prescribed protective measures.
The wear reserve is dimensioned so that inspection and maintenance can normally follow fixed intervals; only very frequently operated breakers may need earlier service once the permissible number of mechanical or fault-current operations is exceeded. Services are offered individually by Siemens AG and may only be carried out by or under supervision of qualified personnel; maintenance kits with the spare parts for each service are supplied by Siemens, and stocking them customer-side is discouraged because parts such as O-rings age. The schedule clock starts on the date the filter material is installed and the breaker evacuated and gas-filled — normally the year of production — regardless of when the breaker actually enters service.
Key safety rules for maintenance: relax the springs in the defined 5-step sequence (switch off motor power, open, close, re-open the breaker, disconnect control voltage); relieve pole-column pressure before opening interrupter units; SF6 is about five times heavier than air and concentrations above 19 vol.-% demand special protective measures; arc decomposition products and switching dust are toxic and, combined with moisture, caustic — use dust masks, gas-tight goggles and protective clothing, and follow IEC 376 / DIN VDE 0373 Part 1 and IEC 480 / DIN VDE 0373 Part 2 for handling SF6.
| Service | Due after time | Due after wear | Remarks |
|---|---|---|---|
| Routine inspection | 12 years | after 3000 operating cycles I ≤ I rated | Breaker taken out of service and isolated. Gas compartments need not be opened. |
| Major inspection | 25 years | after 6000 operating cycles I ≤ I rated | Breaker taken out of service and isolated. Gas compartments are opened. |
| Contact system check | — | permissible number of fault current operations equalled (see 3-100) | Breaker taken out of service and isolated. Gas compartments are opened. |
The general check is a visual inspection without dismantling: SF6 pressure against the temperature-corrected filling curve (top up if no more than 0.3 bar/0.03 MPa/4.4 psig below the curve; below that, find and repair the leak first), contamination of insulating parts, porcelain damage, and the operations counter. SF6 is drawn off with a service unit for near-complete re-use. For the contact system check, only the contact carrier with pin and contact fingers is removed: in new state the pin protrudes 9.5 mm beyond the nozzle guide, and if the remaining length 'a' is below 7 mm — or if spatter marks on the contact-finger front edge exceed 2 mm axial width — the contact carrier and moving contact must be replaced (contact Siemens Service Berlin).
On reassembly, sealing faces are cleaned and greased (sealing rings with Vaseline 8420; flange faces inside the rings with WD 40, outside with Tectyl 506) and new sealing rings fitted. Filter bags in the corner gear are replaced, never exposed to open air for more than one hour, and fitted at most one hour before evacuation. The breaker is evacuated to ≤ 20 mbar/0.002 MPa/0.29 psig and refilled per the filling curve, with the filling device's 8 bar safety valve mandatory. Further checks: breaker pressure gauge divergence from a class 0.6 test gauge not more than 0.3 bar/0.03 MPa/4.4 psi (note divergence above 0.2 bar on the gauge); density monitor function and operating values via test connection W2 (3/4-inch thread) with filling device W424; leak search on the operational breaker with a leak detector, spray or soap solution; dampers inspected for yellowish oil traces; trip coil plate (M6x40, 8 ± 1 Nm) and latching blocks (M10x70, 40 ± 4 Nm) checked for firm seating; functional checks of trip circuits, reclosing lockout, SF6 lockout, anti-pumping feature and motor control; SF6 humidity (critical dew point limit -5 °C/+23 °F; maximum permissible during commissioning/operation -10 °C/+14 °F — dry the gas if exceeded) and air content (max. 5%, SF6 volumetric portion at least 95%, measured e.g. with DILO percentage instrument 3-027); anti-corrosion touch-up; and review of special occurrences since the last maintenance.
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