Top 3 common faults of GW5 outdoor isolation switch

2025-07-15 13:40:15

The following are the root solutions for the three high-frequency faults (heating, refusal to move, and insulator flashover) of GW5 outdoor isolation switches. Based on the analysis of fault mechanisms, standardized processing procedures, and prevention strategies, they are strictly formulated in accordance with industry standards and engineering practices:

1、 Contact point heating: a radical solution for oxidation and insufficient pressure

Root Causes of Failure

1. Contact oxidation: The outdoor environment causes oxidation of the contact surface between the contact finger and the contact finger holder, resulting in an increase in resistance.   

2. Insufficient spring pressure: High current impact causes the spring to anneal, resulting in a decrease in tension and forming a vicious cycle of "heating → annealing → hotter".   

3. Overload or poor contact: Insufficient effective contact area of the contact or loose connecting bolts.   

Radical Steps

1. Sandpaper polishing+contact surface treatment

-Power off operation: Use "0-0" fine sandpaper to remove the contact oxide layer, and avoid using coarse sand or files (to avoid damaging the flatness).   

-Cleaning and protection: After alcohol cleaning, apply neutral Vaseline or conductive paste (for oxidation prevention and resistance reduction).   

2. Spring pressure testing and adjustment

-Standard value: The initial pressure of the contact should reach 18-22N (250A level), which can be detected using a spring scale or pressure sensor.   

-Insufficient stress treatment:

-Replace the annealed spring (choose high temperature resistant material);   

-Install copper shunt tape: Drill holes to fix laminated soft copper tape between the contact finger and the contact finger seat, sharing more than 50% of the current.   

3. Overload and connection reinforcement

-Load reduction operation: If the current exceeds the set value, limit the load or replace the high-capacity switch.   

-Bolt tightening: Use a torque wrench to tighten according to specifications (such as 45N · m for M10 bolts), and apply thread locking adhesive to prevent loosening.   

>Case: The contact of GW5-126 in a coastal substation generates an annual heat of over 70 ℃, and after adding a current strip, the temperature drops below 45 ℃. The maintenance cycle is extended to 3 years.

2、 Operating mechanism refusal to move: precise troubleshooting of jamming and motor faults

Root Causes of Failure

1. Mechanical jamming: rusting of the transmission shaft pin, disengagement of the bevel gear, and freezing of the vertical connecting rod (due to water ingress in winter).   

2. Motor malfunction: phase loss, burnt AC contactor contacts, or broken control circuit.   

Five step investigation process

1. Power off inspection lock: Confirm that the mechanical lock has been released (the main knife and ground knife lock plates are separated).   

2. Manual resistance testing:

-When operated with a shaking handle, it is judged to be stuck when the resistance is greater than 250N · m;   

-Focus on checking the corrosion of the bearing seat (accounting for 60% of the blockage) and the meshing status of the bevel gear.   

3. Lubrication and maintenance:

4. Motor circuit detection:

-Measure the three-phase resistance of the motor (deviation ≤ 10%);   

-Check the contact points of the opening and closing contactors, and replace them if the erosion area is greater than 30%.   

5. Anti freezing treatment: Drill drainage holes (Φ 6mm) at the bottom of the vertical connecting rod to prevent water accumulation and frost heave.   

>Warning: Do not forcefully operate when stuck! In a certain case, strong pulling caused the fracture of the porcelain pillar, resulting in a short circuit of the busbar.

3、 Integrated prevention and control of insulator flashover: pollution and wet flashover

Root Causes of Failure

1. Accumulation of pollution: Salt spray/industrial dust forms a conductive layer when exposed to moisture, causing a surge in leakage current.   

2. Insufficient climbing distance: The standard climbing distance for ceramic columns is 20-22mm/kV, and for Class IV polluted areas, it must be ≥ 25mm/kV.   

3. Failure of RTV coating: Loss of hydrophobicity due to UV aging or mechanical damage.   

Triple protection scheme

1. Construction of RTV anti fouling flash coating

-Clean the surface: Wipe the porcelain surface with anhydrous ethanol, free of oil and dust.   

-Coating process:

-Spray twice, with a thickness of 0.3~0.5mm;

-Hydrophobicity test (HC1~HC3 level qualified), valid for 5 years.   

2. Cleaning and Creepage Enhancement

-Cycle: twice a year in Grade IV polluted areas (before rainy season+before snowmelt), and once in other areas.   

-Climbing measures:

-Replace the anti fouling ceramic pillar (with a crawling distance of ≥ 31mm/kV);   

-Install a climbing skirt (with a 30% increase in umbrella diameter to block sewage curtains).   

3. Fracture prevention

-Ultrasonic testing: Annual inspection to detect internal cracks in ceramic columns (replace if>1cm);   

-Cement adhesive surface protection: modified silicone rubber adhesive (crack resistant+hydrophobic).   

>Case: After applying RTV to GW5-126 of a power plant in Hebei, the pollution flashover voltage increased from 48kV to 72kV without any further flashover.

4、 Preventive Maintenance Cycle Table and Cost Comparison

>Economic conclusion: Preventive investment can reduce annual maintenance costs by 60%.

Ultimate suggestion: full lifecycle management

1. Selection stage: GW5-126W anti fouling type (climbing distance 31mm/kV+stainless steel bearings) is directly selected for heavy pollution areas.   

2. Operation and maintenance monitoring:

-Quarterly inspection of infrared temperature measurement (warning for contact point temperature rise>35K);   

-The compulsory inspection mechanism is jammed after rainstorm/icing.   

3. Technical transformation:

-Renovation of the entire flow band at high-risk fever points;   

-Upgrade the operating mechanism to an electric version (such as CJ12A-G, to reduce manual operation injuries).   

>Root cure essence: Heat generation relies on diversion and load reduction, refusal to move relies on precise lubrication, flashover relies on RTV+climbing - the three in one can improve the service life of GW5 to 25 years.