What Are The Factory Test Of Elbow-type Surge Arresters

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 I.Scope and Standards

1. Product Scope

American-style pad-mounted substations, cable distribution boxes, and ring main units equipped with 200A plug-in elbow-type gapless zinc oxide surge arresters (main specifications: 17/50 kV and 24/60 kV), integrated EPDM rubber shielded elbow housings, internal zinc oxide MOV varistors, andgrounding braided copper wire.

2. Applicable Standards

GB/T 11032 “AC Gapless Metal Oxide Surge Arresters,” IEEE 386, ANSI C37.42, JB/T 7618 sealing test, T/CS 496 distribution surge arrester standard, and general specification for cable plug-in connectors.

3. Inspection Categories

1) Full inspection per unit (100% mandatory factory inspection): appearance and dimensions, insulation resistance, DC reference voltage U1mA, leakage current at 75% U1mA, power frequency withstand voltage, partial discharge, seal leak testing, grounding continuity;

2) Sampling inspection (2 units out of every 50): lightning residual voltage, square wave impulse withstand capability, mechanical strength of plug-in connection;

3) Type testing (annual or upon process change): operating load, thermal stability, high-low temperature and humidity tests, salt spray test, pressure release test.

II. Full Factory Inspection Process (Production Line Sequence)

Process 1: Incoming Material Verification + Visual and Structural Inspection (100% per unit, visual inspection + caliper measurement)

1. EPDM insulating elbow housing inspection

2. Internal valve disc assembly and grounding components

3. Nameplate marking verification (mandatory item)

4. Dimensional accuracy testing

Process 2: Insulation Resistance Test (100% per unit, using 2500V megohmmeter)

Process 3: DC Reference Voltage and Leakage Current Test (core electrical mandatory test)

Test equipment: DC high-voltage generator + high-precision microammeter

Process 4: Power Frequency Short-Time Withstand Voltage Test

Process 5: Partial Discharge Detection (100% factory mandatory test, conducted in shielded test chamber)

Process 6: Sealing Performance Leak Test (100% per unit, two methods available)

Option A: Helium mass spectrometer vacuum leak detection (high precision, for premium products)

Option B: Hot water immersion test (economical batch method)

Process 7: Grounding Circuit Continuity Test

1. Use continuity tester to measure DC resistance from internal conductive core to grounding copper wire;

2. Pass criteria: Grounding circuit resistance ≤ 0.05Ω; inspect for loose crimping, broken copper strands, or poor flange connections to ensure reliable fault current dissipation to ground.

Process 8: Sampling Electrical Performance Spot Check

1. Residual Voltage Test under Rated Discharge Current

Apply 5kA/10kA 8/20μs lightning impulse current; record residual voltage. Residual voltage must not exceed 5% of the rated value to verify overvoltage suppression capability.

2. Square Wave Impulse Current Withstand Test

Apply 100A square wave current (2ms duration), 20 impacts without breakdown or cracking, and residual voltage change <10%, evaluating energy tolerance of valve discs.

3. Mechanical Strength Test for Plug-and-Extract Connection

Standard 200A plug-and-extract connector cycled 50 times:

• No wear on conical surface, shielding layer intact;

• Stable insertion torque with no sudden changes, no increase in contact resistance; simulates reliability under repeated field installation and removal conditions.

Process 9: Final Product Cleaning, Protection, and Packaging Inspection

1. Wipe off oil stains and dust from housing; apply dedicated silicone grease on plug-and-extract cone surfaces;

2. Install dust-proof protective caps at both ends; secure grounding copper wire by winding to prevent bending;

3. Pack individually in anti-static bubble bags, then into rigid cardboard boxes with buffer foam padding to prevent damage during transportation;

4. Each box includes a factory certificate indicating batch number, inspector name, inspection date, and key electrical parameters.

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