Keep the intake clear by raking the trash rack every day and after every storm, and in freezing weather either keep water moving through the system or drain the penstock, because water that freezes in a full pipe can split it. Bury the penstock under 0.5 to 1 meter of cover for frost protection, as the installation page advises, and treat any ice on the intake as a reason to inspect the plant that day.
Part of Micro-Hydro Turbine
Leaves, sticks and stones in autumn and storm flows, and ice in winter, are the two things that stop an otherwise sound plant; both arrive at the intake first.
Debris Arrives With Storms And Leaf Fall
The carrier makes the rack a daily check, especially after rain, and says to clean it after every storm. One stick lodged in the turbine can halt production for hours, so the rack’s job is to catch it first (Intake & Trash Rack).
Method: A Rack Routine
Step 1: Fit a rake that matches the bars. A long-handled rake with tines at the same spacing as the bars (2-3 cm on the carrier’s coarse rack) lifts debris up the bars without bending them.
Step 2: Rake from the bank or a platform, with the intake gate shut if the rack is hard to reach. Never step into the flow.
Step 3: Put the debris well away from the channel, where a rising stream cannot carry it back.
Step 4: Mark a water-level line on the rack frame. If the water upstream of the rack stands visibly higher than the water below it, the rack is blocking and the flow to the penstock is falling. Hydro power is proportional to flow, so a rack that passes half the water gives half the power (Power Calculation).
Step 5: After a storm, check the whole path in order: rack, basin (it fills with sand), and the penstock for rocks or soil washed against it (Penstock Leak Repair).
Ice Stops Water In Three Places
- At the intake. Ice that forms on the rack and the weir blocks the flow just as leaves do. In very cold, turbulent streams, small ice crystals can form in the water itself and clog a rack even while the surface is open; this is a recalled effect, not from the corpus. Rake more often, and look for it first when output falls on a cold morning.
- In the penstock. Water in a pipe that stops moving can freeze. The installation page buries the pipe with 0.5 to 1 meter of cover to protect it from frost and damage; that depth is a minimum for mild frost, not a guarantee for a hard one. Freezing water expands, and a full rigid pipe can split. In a long freeze either keep the plant running, so water flows all the time, or close the intake gate, open the drain at the low point and the air valves at the high points, and empty the pipe.
- In the powerhouse. A frozen bearing or wet insulation causes faults. The dump load that holds the generator steady produces heat; in a cold powerhouse, a water-heater-type element inside the building turns waste power into frost protection (Load Control). A 350 W plant produces 350 × 24 = 8,400 Wh of heat a day if all of it goes to the dump load.
When The Stream Itself Freezes
If the stream flow drops sharply in a freeze, the plant’s output drops too; this is the seasonal low flow in Seasonal Variation. Plan the winter loads for that low and not for the autumn peak.
Common Mistakes
- Raking only when output has already fallen — a daily routine catches the block earlier.
- Draining the penstock without opening the high-point air valves — a pipe that cannot take in air drains slowly and can be damaged.
- Leaving a full pipe unattended through a long freeze.
Safety
Ice and water near the intake
Ice over a stream is thinnest near an intake and a weir, where flowing water undercuts it. Do not walk on it. Rake from firm ground with a second person watching, and close the intake gate before reaching toward the rack. Slippery banks need cleats or ash on the steps.
What’s Next
- Learn next: Penstock Leak Repair for what a frozen or stone-struck pipe may need
- Combine with: Maintenance & Troubleshooting for the full routine