ມາດຕະຖານເຕັກນິກ ໄຟຟ້າ ຂອງໄຟຟ້າລາວ

 

ມາດຕະຖານເຕັກນິກ ໄຟຟ້າ ຂອງໄຟຟ້າລາວ ສະບັບພາສາລາວ, ສະບັບພາສາ ອັງກິດ

6.2 Standard Voltages and Frequency

EDL has adopted a rationalized range of transmission and distribution voltages aligned to British,

European and IEC practice. These include 115kV(110kV), 22kV, and 380/220v.

12.7kV SWER1 is in use and is a logical derivative from 22kV as the same insulators and fuses as

on the 3-wire 22kV system can be utilized. 12.7kV is the phase to the ground voltage on a three-phase

22kV system.

The use of 25kV and 34.5kV for shieldwire based distribution is an unfortunate departure towards

American standard voltages which have required the purchase and stocking of different

transformers, insulators, MV fuses, and related hardware.

The standard frequency is 50Hz.

6.2.1 Transmission

EDL has adopted 115kV as its standard transmission voltage. The system is three-phase, solidly grounded. All transmission lines are constructed on steel towers and most are single circuits.

Transmission and major substation voltage ratings and insulation levels are based on:

• Nominal voltage 115kV
• Highest (operating) system voltage approx. 120kV
• Highest system voltage for equipment (Um) 123kV
• Power frequency withstand 230kV
• Rated impulse withstand 550kV

Some older substations have 110kV nominal rated equipment with insulation levels as above.

The above values are consistent with Um = 123kV from Table 2 range 1 of IEC 60071-1. Some segments of the transmission network utilize shieldwire(s) insulated from the ground to afford a local distribution supply. Because of the particular insulation coordination requirements of the shieldwire system and the chosen distribution voltages, the next highest level of insulation ratings

from IEC60071-1 has been adopted. The relevant ratings are:

• Nominal voltage 115kV
• Highest (operating) system voltage approx. 120kV
• Highest system voltage for equipment (Um) 145kV
• Power frequency withstand 275kV
• Rated impulse withstand 650kV

Both 115kV and 110kV (nominal voltage) power transformers have on-load or off-load tapping facilities with a sufficient range to be operated at 115kV. However, it should be noted that the tap change equipment is operated near one extremity of the design range.

Voltage transformers at major supply substations have 110volt or 100volt secondary windings some of which are configured 110/√3 or 100/√3volt.

ທ່ານສາມາດ ດາວໂຫລດ ສະບັບເຕັມທີ່ນີ້