Lightning Arresters. Construction and Condition Monitoring . LA Characteristics. Arrester Fundamentals. Need for High Resistance to limit Discharge Current Need Low Resistance during flow of lightning current to limit Surge Voltage . A non-linear resistance material required.
Construction and Condition Monitoring
A non-linear resistance material required
temperature and voltage
Voltage 400/√3 = 230kV
During single phase to ground fault, voltage on healthy phase may go upto 1.4 to 1.5 times
230 x 1.4/1.5 = 323 – 346
Temporary O/V = 1.5 pu = 336kV
LAs are available at 336kV, 360kV, 372kV and 390kV
Higher ratings are selected taking into consideration of ageing of LA elements
Meter Terminal Fixing:
Meter Enclosure :
1. TOTAL LEAKAGE CURRENT MEASUREMENT
2. WATT LOSS MEASUREMENT
3. INSULATION RESISTANCE MEASUREMENT
4. THIRD HARMONIC RESISTIVE CURRENT MONITORING.
5. THIRD HARMONIC RESISTIVE CURRENT (THRC) MONITORING WITH COMPENSATION FOR THIRD HARMONICS IN SYSTEM VOLTAGE.
LA SURGE ARRESTERS IN SERVICE
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