水电运维管理

Unit 2 has been running for 18,000 hours since the last major overhaul. The vibration levels at the turbine guide bearing have been trending up — from 45 μm to 78 μm over the past 6 months. The DGA on the thrust bearing oil showed elevated metal particles. It's time for the A-class overhaul. Let's plan the disassembly sequence.

We start with the generator disassembly — disconnect the bus, remove the upper bracket, pull the rotor. Then the turbine: drain the spiral case and draft tube, remove the head cover, lift the runner and shaft as an assembly. The key inspection items: runner cavitation damage — we've repaired pitting on 7 of 13 blades in the last overhaul, let's see how the repairs held up. Guide vane end clearances — specification is 0.15-0.25 mm; if any gap exceeds 0.40 mm, we replace the wearing plates. Wearing rings on the runner and stationary parts — the radial clearance should be 0.8-1.2 mm; above 2.0 mm, we need re-machining or replacement.

And the thrust bearing? That's the most expensive single component to repair if it fails. We need to inspect the thrust pads — look for scoring, wiping, or babbit metal fatigue. Measure the pad thickness and compare with the as-built records. If any pad has lost more than 0.05 mm of babbit, we re-pour or replace. Also, the oil bath must be thoroughly cleaned and filtered — metal particles circulating in the oil will damage the new pads. I want the oil analyzed before and after cleaning to confirm zero particle count above 5 microns.

The rainy season forecast is out — the meteorological agency predicts 30% above-average precipitation in the catchment area over the next 3 months. We need to review the dam safety monitoring data and prepare the flood control plan. Let me walk you through the current monitoring readings.

Go ahead. I'm particularly concerned about the seepage trend through the left abutment. Last season we had a slight increase there.

The seepage monitoring shows: total seepage through the dam body currently at 12 L/s — that's stable compared to the same period last year. The left abutment uplift pressure at piezometer P-12 is reading 0.32 MPa — that's actually 8% lower than last year, suggesting the grouting work we did in January has been effective. Displacement monitoring: the crest has moved 3.2 mm downstream from the zero reading — normal seasonal variation, well within the 15 mm warning threshold. Pendulum readings in the gallery show no anomalous deformation. Overall, the dam is in good condition.

That's reassuring. Now the operational plan for the rainy season: we need to pre-release water to bring the reservoir level from the current 245 meters down to the flood control level of 240 meters before the heavy rains arrive. That's about 18 million cubic meters to release through the turbines over the next 10 days — we can generate while lowering the level. At 240 meters, we have 45 million cubic meters of flood storage capacity. The spillway gates must be tested this week — open each of the 5 radial gates through a full cycle and verify the emergency power supply for gate operation.