Читать книгу Practical Power Plant Engineering - Zark Bedalov - Страница 43

The electrical equipment will be operating at an altitude of 1700 m. The equipment shall be derated for the altitude in accordance with the applicable ANSI C57.40 and IEC 282‐1.2 standards. The following derating factors are applicable for the 1700 m site altitude:

 Voltage: 0.93

 Current: 0.99

The voltage derating will be factored by the suppliers of the equipment, such as switchgear, transformer bushings, to ensure the equipment insulation is designed for lower air density at the specified altitude. The current (ampacity factor) derating for the plant cables is not significant, well within our conservative plant selection estimates.

Applicable ANSI or IEC standards for ampacity derating factors will be used for the power cables buried or installed in multiple duct banks, also discussed in Chapter 12.

The other site ambient conditions, such as road conditions, minimum/maximum temperatures, humidity, rainfall, number of lightning days, are normally included in the tender document for the vendors to design the equipment accordingly.