How do you determine lightning arrester rating?
How do you determine lightning arrester rating?
Selection of LA
- For 220KV side: Voltage rating = 1.1 × 220 × 0.8 = 193.6KV. Power frequency spark over voltage = 1.5 ×193.6 = 290.4KV.
- For 110KV side: Voltage rating = 1.1 × 110×0.8 = 96.8KV.
- For 66kV Side. Voltage rating = 1.1 × 66×0.8 = 58.08kV.
- For 11 KV side: Voltage rating = 1.1× 11×0.8 = 9.68KV.
What is UC voltage?
Maximum continuous operating voltage (Uc): the maximum voltage which may be connected to the SPD (sometimes referred to as its “rated voltage”. If no such waveshape or amplitude is defined, Up is assumed to be stated when the SPD is subjected to the nominal discharge current In.
What does MCOV stand for?
Maximum Continuous Operating Voltage
MCOV stands for the Maximum Continuous Operating Voltage. COV or UC stands for Continuous Operating Voltage. They represent the power frequency voltage that may be continuously applied to a surge arrester.
What is discharge class of lightning arrester?
ABB Surge Arresters Overview
| Surge Arrester Type | POLIM-D | POLIM-K |
|---|---|---|
| Continuous Operating Voltage Uc | ≤ 44kV | ≤ 44kV |
| Nominal Discharge Current ln | 10kA | 10kA |
| High Current Impulse | 100kA | 100kA |
| IEC Line Discharge Class | 1 | 2 |
What is done during lightning arrester testing?
Capacitive compensation by combining the leakage current of the three phases. Third order harmonic analysis. Direct determination of the power losses. Third order harmonic analysis with compensation for harmonics in the voltage.
How do high voltage lightning arresters work?
A surge arrester works by diverting the extra voltage into the earth wire, rather than flowing through the electronic devices, while at the same time allowing the normal voltage to continue along its path.
What does UC mean in electrical terms?
The unit commitment problem (UC) in electrical power production is a large family of mathematical optimization problems where the production of a set of electrical generators is coordinated in order to achieve some common target, usually either matching the energy demand at minimum cost or maximizing revenue from …
How do I choose a surge arrester?
The two most important factors used to select an arrester rating are the system voltage and the neutral grounding configuration of the source transformer. These tables assume that the maximum duration and amplitude of the worst-case overvoltage during a line-to-ground fault are unknown.
What is discharge current of lightning arrester?
The peak current levels can vary from 125 amps to 2000 amps, depending on the class of the arrester. This discharge voltage represents the response of an arrester to a slow-rising surge generated within the power systems during breaker or switch operations.
What is the mcov of an arrester?
When arresters are applied to protect systems from lightning or switching surges, they are installed between the phase and earth. For this application, the MCOV of the installed arrester must be equal or higher to the continuous voltage between the phase and earth.
What is the discharge voltage of a lightning arrester?
The lower the discharge voltage, the better. Continuing with the above example, an 88kV MCOV arrester when subjected to a 10kA lightning impulse generates 254kV discharge voltage across arrester terminals. This is acceptable considering this rating is well below the adjusted BIL rating of a 138kV piece of equipment (520kV).
What is mcov rating on a power supply?
Maximum Continuous Operating Voltage (MCOV) Rating It is a phase-to-ground voltage rating above which the arrester operates. Consequently, pick a rating that is higher than your maximum (phase-to-ground) system voltage. However, how high would you choose?
What does mcov stand for?
MCOV rating (IEEE) – The maximum designated root-mean square (rms) value of power frequency voltage that may be applied continuously between the terminals of an arrester.
