Extrusion Equipment in the Rainy Season

 

 

 

1. Prevent backflow of rainwater, ensure cable trench drainage, and apply firestop sealing. Consider temporarily raising the cabinet for waterproofing if needed.
2. Raise the threshold at the distribution room entrance. Minor seepage in cable trenches is usually fine since cable sheathing is waterproof. Keep trench covers on to prevent large-scale flooding and submerged cables.
3. To prevent short circuits or blowouts, cut power immediately at the main switch and post someone to watch. Warning: if water is already around the cabinet, don't pull the switch by hand-use an insulated rod or dry wooden stick, wear insulating gloves and safety glasses, and stand on an insulating mat to avoid arc flash and electric shock.

 

 

 1. First inspect the pipe production line cabinet. If there's obvious moisture or flooding, do not power it up. A qualified electrician must:

    a. Use a voltage tester to check if the cabinet shell is live.

 

    b. Check low-voltage components-control circuits, breakers, relays, terminal blocks-for moisture. Dry them promptly if damp. Replace any obviously rusted parts.

 

 2. Before powering up, measure insulation on every load cable-phase-to-phase and phase-to-ground. For rated voltage below 500V, use a 500V megohmmeter; insulation must be at least 0.5MΩ. Dry and air-dry every component inside the cabinet.

 

 

First thing: a VFD getting wet isn't the real problem-getting wet and powered up is. That's usually beyond repair, and you're lucky if it doesn't explode. If it's flooded while not powered, it can be fully recovered. If flooded while running, damage is certain, but cut power immediately to prevent internal wiring from burning and causing a fire. Fire precautions must be in place.

Steps for a flooded but unpowered VFD:

1. Never power it up. Open the panel and wipe down all parts.
2. Use a hair dryer on cool setting to dry the display, PC boards, power components, fans, etc. Don't use hot air-excessive heat can damage components.
3. Wipe the above parts with 95% ethanol, then blow-dry again with cool air.
4. Air-dry in a ventilated, shaded spot for one hour, wipe with ethanol again, and blow-dry with cool air.
5. Alcohol evaporation carries away most moisture. Now use low-heat setting to blow-dry the components again.
6. Focus on these parts: potentiometers, switching power supply transformers, displays (buttons), relays, contactors, reactors, fans (especially 220V), electrolytic capacitors, power modules. Use low heat and dry multiple times. Transformers, contactors, and power modules are the priority.
7. After the six steps, check for residual water in the module. Wait 24 hours, check again for moisture return, and dry the key components once more.
8. After drying, try powering up-but switch it off immediately after. Watch the VFD's response. If normal, it can be used.

 

If you can't disassemble it, just let it air-dry for several days. Once fully dry, blow filtered compressed air through the gaps to clear dirt left by rainwater, which can cause poor heat dissipation and alarm shutdowns.

 

Bottom line: as long as a flooded VFD isn't powered up, it's usually fine. The same method applies to PLCs, switching power supplies, AC systems, and other boards.

 

 

1. Remove the motor, wrap the power cable, detach the coupling, fan cover, fan blades, and end caps. Take out the rotor, open the bearing covers, and clean bearings with gasoline or kerosene. Replace bearings if severely worn, then re-grease. Grease amount: half the bearing capacity for 2-pole motors, two-thirds for 4- and 6-pole motors. Use calcium-sodium base high-speed grease.
2. Check stator windings with a 500V megohmmeter for insulation resistance between phases and to ground. If below 0.5MΩ, dry the windings. Clean oil stains with gasoline. If insulation is aged (brown color), preheat the windings, apply insulating varnish, and dry. Drying methods:

    a. Light bulb method: aim infrared bulbs at the windings, heating one or both ends.

    b. Electric stove or coal stove method: place a stove below the stator with a thin iron plate between them for indirect heating. Cover the stator with an end cap and burlap. Flip the stator midway through drying. Watch for fire-varnish and its vapors are flammable.

 

 

Moisture is a major cause of pipe production line motor failure. Splash water or condensation can get into motors, especially after months of idle storage. Always check coil insulation before use, or you risk burning the motor. Methods for damp motors:

1. Circulating hot air drying: build a drying chamber (e.g., firebrick), with an air outlet on top and inlet on the side. Keep hot air around 100°C.
2. Light bulb drying: place one or several high-wattage incandescent bulbs (e.g., 100W) inside the motor cavity. Keep bulbs away from coils to avoid burning them. Cover the motor shell with canvas for insulation.
3. Desiccants:

    a. Quicklime desiccant. Main component is calcium oxide. It absorbs moisture through chemical reaction-irreversible. It maintains absorption capacity greater than 35% of its own weight regardless of humidity, works well at low temperatures, and is cheap.

    b. Silica gel desiccant. Moisture-permeable bags of various silica gel types. Main material is highly microporous hydrated silica-non-toxic, odorless, chemically stable, with strong moisture absorption. More expensive.

 4. Self-heating air drying: for those without tools or experience. Takes longer. Always test motor insulation before powering up.

 

Also: to avoid electric shock from residual water inside the pipe production line, after confirming the equipment is fully dried, leave it in a ventilated, dry place for about a week before use. Check the grounding wire-water can cause short circuits in grounding.

 

If you can't handle it yourself, contact us for inspection and repair to prevent worsening the damage.