Why does a 42kV-rated arrester pair with a 27.5kV system?
A 27.5kV OCS system uses an arrester rated 42kV; the YH5W series has a continuous operating voltage of 31.5kV or 34kV and a DC 1mA reference voltage of at least 60kV or 65kV, meeting GB/T 11032 and the traction power supply system technical conditions. The Chuangwit Y10WT/Y5WT/YH5WT/YH10WT and YH5W series are all rated 42kV (for 27.5kV systems) — just verify the rated voltage against the system voltage when selecting.
How to choose between porcelain and composite housing arresters?
By installation scene and anti-pollution requirements. Porcelain Y5WT/Y10WT offers high mechanical strength and good weather resistance with 1600mm creepage distance; silicone-rubber composite YH5WT/YH10WT is light, explosion-proof and hydrophobic with 1400 to 1600mm creepage. Fixed locations such as substation exits can use porcelain; OCS lines, outdoor suspension and heavily polluted sections prefer composite housing.
How to choose between 5kA and 10kA nominal discharge current?
Match the line lightning-hazard class and speed. Y5WT-42/120 and YH5WT-42/120 have 5kA nominal discharge current and 400A 2ms square-wave withstand; Y10WT-42/120 and YH10WT-42/120 have 10kA nominal discharge current and 600A withstand. Choose the 10kA class in high-activity lightning areas; 5kA covers ordinary sections. For speed, composite-housing YH5WT/YH10WT applies to 200 to 250km/h, while porcelain Y5WT/Y10WT covers the 200km/h class.
How to assess protection level by lightning impulse residual voltage?
The lower the residual voltage, the higher the protection level. YH5W composite-housing arresters come in 110/120/128/140kV lightning impulse residual voltage grades; the YH5W-42/110 has lightning impulse residual voltage at most 110kV, steep-wave at most 127kV and switching at most 94kV — a large protection margin. Select the grade against the impulse withstand voltage of the protected insulation; the residual voltage should not exceed the withstand value.
| Model | Housing | Nominal discharge current |
|---|---|---|
| Y5WT-42/120 | Porcelain | 5kA |
| Y10WT-42/120 | Porcelain | 10kA |
| YH5WT-42/120 | Composite | 5kA |
| YH10WT-42/120 | Composite | 10kA |
| YH5W-42/110, YH5W-42/120 | Composite | Per model |
Manufactured to GB/T 11032 — metal-oxide surge arresters for 27.5kV OCS, with disconnector optional.
