At Beckton Sewage Treatment Works — one of Europe’s largest — a modernisation project replaced the actuators on 12 large penstocks at the coarse screen outlets with AUMA SAV variable-speed (inverter-driven) actuators: the motor now runs at the optimum speed at each stage of travel and slows down for a soft landing near the closed position, cutting mechanical stress and extending penstock life. The 2026 case answers a common question — do large gates justify variable-speed actuation? The heavier the gate and the longer the stroke, the higher the cost of constant-speed hard seating.
Beckton STW sits in the east-London borough of Newham, covers over 100 hectares and serves much of London north of the Thames. The 12 large penstocks at the coarse screen outlets previously ran on single-speed actuators, hammering into position at each end of travel — high mechanical stress, fast wear on gates and seats. AUMA recommended SAV variable-speed actuators: the motor runs at the optimum speed at each stage of the stroke, combining fast travel with reduced speed in the critical zone — a "sympathetic" approach to working with the existing penstocks.
Penstocks at the coarse screen outlets, Beckton STW (source: AUMA)
| Item | Details and value |
|---|---|
| Automatic greasing | Every SAV actuator has an individual automatic greasing cartridge on the thrust base; one cartridge lubricates both the bearings and the penstock rising stem on each gate — timed release extends the life of the whole system and removes manual greasing |
| Controls & interfaces | Standard parallel controls with 24 V DC commands and 4–20 mA position feedback; plus Profibus interfaces — currently unused, but no hardware or software changes needed to upgrade to Profibus later |
| Variable-speed value | Motor speed per travel stage: fast travel plus soft landing at the ends; less impact damage to gate and seat, longer service life |
AUMA SAV variable-speed actuator (source: AUMA)
(1) Large gates — especially at coarse screens or high-head inlets — justify variable speed: end-of-travel hammering is a main cause of seat damage; soft landing extends overhaul intervals. (2) Automatic greasing is low-cost, high-return: rising-stem lubrication is easily neglected; timed cartridges beat manual greasing. (3) Reserve a fieldbus interface: parallel + analogue today, Profibus fitted — SCADA/digital-twin upgrades later need zero rework. Chinese inverter-driven actuators (Chuanyi M8000, SJMC M-series) suit the same duty.
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Source: AUMA newsroom, "AUMA variable speed actuators prolong penstock lifetime" (2026); compiled by actuators.cn. SAV = AUMA’s built-in inverter-speed range; "variable speed" in English, commonly called inverter actuators in Chinese.
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