Submersible Sewage PumpsStarting Large Submersible Pump Motors: Four Methods Compared
Direct-on-line, star-delta, soft-start and VFD starting compared for 45-250kW submersible sewage pump motors, with the trade-offs that actually matter on site.

Model: WQ/QW
GAK-series auto-coupling accessory system for WQ/QW submersible sewage pumps, sized GAK-50 through GAK-500, for pit-free fixed installation.
| Flow Rate | 7-2650m³/h |
|---|---|
| Head | 7 – 60m |
| Power | 0.55-250kW |
| Inlet / Outlet Diameter | 25-500mm |
| Material | Cast Iron,SS304,SS316L |
Every fixed-installation model in this catalogue references a GAK coupling size. Here’s what that’s actually built from: a flange fixed to the pit’s discharge foundation, guide rails cut to the pit’s depth, and a lifting chain. Lower the pump down the rails and it seats and seals under its own weight; pull the chain and it comes back up the same way. Nobody enters the pit either direction.
Sizes run from GAK-50 through GAK-500, matched one-to-one against pump outlet diameter. That matching isn’t flexible across sizes, so confirm it before ordering. The base, rails and chain are priced as separate line items from the bare pump, which catches a fair number of first-time buyers who assume it’s bundled. Retrofitting an existing pump already on-site is usually straightforward, as long as outlet caliber and pit depth are both confirmed up front.
Submersible Sewage PumpsDirect-on-line, star-delta, soft-start and VFD starting compared for 45-250kW submersible sewage pump motors, with the trade-offs that actually matter on site.
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