Ano ang mga pruebas nga kinahanglan i-conduct alang sa load switches?
Isipagtagad nga teknisyano nga may dugang kaayo nga karanasan sa on-site power testing, nagsabot ko sa importansya ug komplikado sa load switch testing. Sa ubos, gisulbaran nako ang akong praktikal nga karanasan aron mas maablihan ang buhata nga proseso sa load switch testing, gikan sa mga item sa pagtest ug mga paraan hangtod sa mga equipment ug espesipikasyon sa proseso.
I. Pormal nga Electrical Performance Testing
(1) Loop Resistance Test
Ang loop resistance mao ang core indicator aron masukat ang conductivity sa load switch. Ang GB/T 3804 ug GB 1984 standards adunay miyembrohon, ang DC voltage drop method gamiton gyud kon ang test current dili mahimong labaw sa 100A. Para sa 10kV load switches, ang standard values naglisan depende sa current rating: ≤50μΩ sa 630A ug ≤20μΩ sa 3150A.
Sa panahon sa pagtest, gamiton nako ang SW-100A dedicated loop resistance tester ug masinop nga isulbad ang test fixture sa contacts. Ang resulta sa pagtest dili dapat mogasak sa 120% sa factory value; kung gasak na, posible nga may poor contact o mechanical damage. Ginatuman nako ang mga pagtest sa stable nga temperatura aron malihok ang mga pagbag-o sa temperatura.
(2) Power Frequency Withstand Voltage Test
Kini nga test nagpakita sa insulation strength sa load switches. Para sa 10kV switches, i-apply nako ang 42kV/1min tali sa phases ug sa ground, ug 48kV/1min sa break, ug ang leakage current ≤0.5mA.
Para sa 24kV switches nga gigamit sa high-altitude environments, ang withstand voltage giadjust sa altitude (7% increase in electrical clearance per 1000m). Gamiton nako ang WGD-40kV withstand voltage tester aron masiguro ang stable nga waveform sa test voltage. Kung may breakdown o flashover, immediate stop ang pagtest aron matubag ug repairo ang insulation defects.
(3) Active Load Current Breaking Test
Kini nga test nag-evaluate sa breaking capability sa load switches batasan sa GB/T 3804. Ginatuman nako ang test sa rated active load conditions, kasagaran sa 100% sa rated current (e.g., 630A).
Sa panahon sa pagtest, gitantanan nako ang transient recovery voltage (TRV) peak ug time coordinates aron masiguro nga nahimong ang design requirements. Para sa E1-class switches (mechanical life ≥100,000 cycles), kinahanglan 10 breaking tests; E2 (≥300,000 cycles) ug E3 (≥1,000,000 cycles) kinahanglan 20 tests. Importante kini sa assessment sa long-term operational performance.
II. Mechanical Condition Testing
(1) Mechanical Life Test
Ang mechanical life mao ang key indicator sa long-term reliability, classified as M1 (≥100,000 cycles) ug M2 (≥300,000 cycles) batasan sa GB/T 3804.
Ginatuman nako ang no-load opening/closing operations ngadto sa SWT11 mechanical characteristic tester aron masulbad ang parameters sama sa operation time, stroke, ug speed hangtud magka-jamming o abnormal movement. Para sa frequently operated switches, gi-recommend nako ang semi-annual mechanical life tests aron masukat ang remaining service life.
(2) Opening/Closing Synchronism Test
Ang synchronism importante sa three-phase switch reliability. Batasan sa GB 1984-2003, ang opening synchronism dapat ≤1/6 cycle sa rated frequency (3.3ms sa 50Hz), ug closing synchronism ≤1/4 cycle (5ms).
Gamiton nako ang high-precision mechanical characteristic tester aron masulbad ang time difference sa three-phase contact operations. Para sa switches nga may arcing contacts, ginadistingyun nako ang main ug arcing contact signals aron malihok ang misjudgment. Kung ang results mogasak sa standards, gi-adjust o replace nako ang components sa operating mechanism.
(3) Contact Pressure and Wear Test
Ang contact pressure ug wear direktang nakapulong sa conductivity. Conventional load switch contact pressure kasagaran ~200N, naglisan depende sa type: plug-in switches (e.g., GW4, GW5) ≥130N per finger, clamp switches (e.g., GW6, GW16) ≥300N, ug clapper switches (e.g., GN2 series) ≥200N.
Gamiton nako ang ZSKC-9000 contact pressure tester aron masukat ang contact pressure sa each finger pinaagi sa simulated contact sensors. Gitantanan usab nako ang wear: para sa vacuum switches, ang moving contact wear marks dili dapat mogasak sa 3mm, o kinahanglan og replacement. Gi-compare nako ang test results sa factory records, gi-replace nako ang contacts kung ang pressure drops by >20% o wear exceeds limits.
III. Insulation Performance Testing
(1) Insulation Resistance Test
Kini nga foundational test gamiton ang 2500V megohmmeter aron masukat ang inter-phase ug ground insulation resistance (≥1000MΩ) ug auxiliary circuit resistance (≥1MΩ for SF6 switches).Masiguro nako nga open ang switch ug isolated sa system sa panahon sa testing. Kung ang insulation resistance drops to <75% sa initial value, gi-suspect nako ang moisture o aging ug conduct further inspections. Ginatuman nako ang resistance tests before ug after sa withstand voltage test—kon ang results differ by >30%, indicated ang insulation defects.
(2) SF6 Gas Insulation Test
Para sa SF6 switches, gitest nako ang gas humidity (≤150μL/L sa arc chambers, ≤300μL/L elsewhere), purity (≥97%), ug tightness (≤10% pressure drop over 24h) gamiton ang GD-3000 detector ug infrared spectrometer.Non-compliant results indicate leakage o contamination, requiring immediate action. Gi-recommend nako ang semi-annual gas testing para sa in-service SF6 switches aron mapalig-on ang insulation stability.
(3) Partial Discharge (PD) Test for Solid Insulation
Kini nga test epoxy ug uban pang solid insulations batasan sa GB/T 3906-2020: PD dapat ≤20pC sa 1.2× rated voltage for solid insulation, ug ≤100pC for air insulation.Ginatuman nako sa fully shielded lab gamiton ang Haefely DDX-9101 PD tester pinaagi sa PD-free transformer, kung exceed ang limits, indicated ang voids o defects sa insulation. Ginatuman nako ang PD tests sa new solid-insulated switches before commissioning aron masiguro ang quality.
IV. Special Environment Adaptability Testing
(1) High-Altitude Environment Test
Batasan sa GB/T 20626.1-2017, giadjust nako ang insulation levels para sa altitude: G2 (1000-2000m), G2.5 (2000-2500m), G3 (2500-3000m), G4 (3000-4000m), G5 (4000-5000m).Gitest nako sa simulated altitude environment (e.g., 80kPa for 2000m), ginaverify nako ang electrical clearances (7% increase per 1000m) ug creep distances (25% increase for pollution level 3). PD testing sa simulation required ≤10pC aron malihok ang corona aging under low pressure.
(2) Extreme Cold Environment Test
Para sa cold regions, gitest nako ang low-temperature insulation resistance (-40°C: main circuit ≥0.4MΩ, auxiliary circuit ≥1MΩ) ug operational performance.Sa -40°C, ginaverify nako ang opening/closing voltage ug synchronism, checking for mechanical jamming. Quarterly cold tests recommended for switches in long-term cold environments.
(3) High-Dust Environment Test
Gitest nako ang IP54+ protection batasan sa GB/T 4208 gamiton ang GD-1000 sand-dust chamber (8-hour test) ug monitor heat dissipation pinaagi sa infrared thermal imager (temperature rise ≤50K under full load).Tri-monthly tests advised to clean dust and replace aging seals.
(4) Coastal Salt Spray Environment Test
Following ISO 9227, conduct CASS (48h, 50°C, pH3.1-3.3) or neutral salt spray (480h) tests, then inspect for corrosion. Tightness verified via pressure decay (≤10% drop in 24h) or helium mass spectrometry.Annual testing recommended for coastal switches.
(5) Industrial Electromagnetic Interference (EMI) Environment Test
Perform EMC compatibility tests batasan sa GB/T 17626.2 (ESD ±8kV), GB/T 17626.3 (radiated immunity 10V/m), and GB/T 17626.12 (damped oscillating magnetic field 200A/m).
For high-frequency EMI, test 3MHz, 10MHz, and 30MHz bands batasan sa IEC 61000-4-18, verifying bit error rate (≤10⁻⁶) and shielded cable grounding resistance (≤0.5Ω). Semi-annual EMC tests advised for EMI-heavy environments.
(6) Photovoltaic-Storage-Charging Integrated Scenario Test
Use a protocol analyzer (e.g., Wireshark) to verify compatibility between energy storage PCS and charging piles (e.g., Modbus RTU). Dynamic load response tests simulate full-load operation of PV, storage, and charging to assess overload capability (120% rated current) and protection timing (PV inverter & PCS trip time difference ≤5ms).
V. Testing Tools and Equipment
(1) Loop Resistance Tester
Harmonic distortion (THD≤5%) and voltage fluctuation (≤2%) are measured at the point of common coupling using an APView400. Quarterly tests recommended for integrated scenarios.
Models like SW-100A and SW-2000 use the DC voltage drop method with 100A+ current, featuring ≤0.1% error for precise measurements. Ensure tight fixture contact and select appropriate ranges for different current ratings.
(2) Mechanical Characteristic Tester
Devices like SWT11 and MOEORW-5180 measure opening/closing speed, synchronism, and contact pressure with ≤1% error. For switches with arcing contacts, distinguish signal points to avoid misjudgment, keeping the sensor vertical to the switch body.
(3) SF6 Gas Detector
Models such as GD-3000 and SF6 purity testers measure humidity (±5% accuracy), purity (±0.5%), and pressure (±0.1%). Use dedicated sampling tubes to ensure representative gas samples for semi-annual testing.
(4) Partial Discharge Detector
High-sensitivity (1pC) testers like Haefely DDX-9101 and Siemens PD160 are used in shielded labs with PD-free transformers for pre-commissioning tests on new solid-insulated switches.
