Zinc Oxide Arrester Installation and Commissioning Specifications: From Construction Preparation to Acceptance and Commissioning

Zinc oxide arresters are key devices in power systems that protect important equipment such as transformers and switchgear from overvoltage impacts. Installation quality directly affects protection effectiveness and equipment life, and must be constructed strictly according to specifications.

I. Pre-construction Preparation

1. Appearance Inspection and Parameter Verification

• Check whether the arrester appearance is intact without damage, and whether the porcelain housing has cracks, damage or deformation
• Verify nameplate parameters: rated voltage, continuous operating voltage, nominal discharge current, residual voltage, etc.,是否符合 design requirements
• Check whether accessories are complete: mounting brackets, connecting bolts, grounding wires, counters (if applicable), etc.
• Measure insulation resistance with a 2500V megohmmeter; for 10kV and above arresters, it should not be less than 1000MΩ

2. Tool and Material Preparation

• Common tools: wrenches, torque wrenches, spirit levels, insulation resistance testers
• Installation materials: bolts, washers, connecting wires, grounding flat steel or copper stranded wires
• Safety equipment: insulating gloves, voltage detectors, grounding wires, safety helmets

II. Installation Steps

1. Foundation Bracket Installation

The arrester bracket should be installed securely, using hot-dip galvanized steel, with base levelness deviation not exceeding 2mm/m. For outdoor installation, the bracket height from the ground should not be less than 2.5m (higher if no obstructions are present).

2. Arrester Body Installation

Install the arrester vertically on the bracket, tighten with bolts, ensuring uniform tightening to prevent uneven stress causing porcelain housing cracking. For multi-section series installation, install from top to bottom section by section, clean the connection surfaces and apply an appropriate amount of conductive grease. The safety distance between the arrester and surrounding live parts and grounded parts should comply with specification requirements.

3. High Voltage Lead Connection

High voltage leads should use soft copper conductors with a cross-section not less than 25mm2. Connections should be firm and reliable with good contact, and should not impose excessive additional mechanical stress on the arrester porcelain housing. The lead sag should prevent rainwater from flowing along the conductor into the connection point.

4. Grounding System Connection

The arrester should be reliably grounded, and the grounding down conductor should be reliably connected to the main grounding grid. Grounding resistance should meet design requirements, generally not exceeding 10Ω. There should be sufficient distance between the grounding device of an independent lightning rod and that of the arrester.

5. Counter Installation (if configured)

The discharge counter should be installed in a position convenient for observation, with correct wiring according to manufacturer's instructions. The counter's lower end should be reliably grounded, and the upper end connected to the arrester bottom, with connecting wire cross-section not less than 10mm2.

III. Commissioning and Acceptance

1. Pre-commissioning Inspection

• Measure insulation resistance again to ensure it meets requirements
• Use a DC high voltage generator to measure the DC 1mA reference voltage (U1mA), deviation from factory value should not exceed ±5%
• Measure leakage current at 0.75 times U1mA voltage, generally required to be not more than 50μA
• Check the tightness of all connecting bolts and reliability of grounding wire connections

2. Acceptance Standards

• Installation position, model and specifications consistent with design drawings
• All connections secure, grounding good
• Insulation test passed, test data within allowable range
• Discharge counter (if applicable) operates normally
• Installation records and test reports are complete

Only through strict installation and commissioning can zinc oxide arresters fully perform their overvoltage protection function, safeguarding the safe operation of the power system.