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Surge Arresters Theory Testing and Commissioning
Chapter 9
Surge Arresters Theory Testing and Commissioning 9.1 INTRODUCTION A surge arrester protects system equipment such as transformers and transmission lines from excessive voltage and/or overvoltage caused by lightning or switching surges. The old design was a gap in series with a nonlinear resistor all enclosed in porcelain cover for protection. The resistance is very low at high voltage and high for low voltages; during high voltages the gap sparks over to protect the equipment, as shown in Fig. 9.1. A new design uses zinc oxide for surge arresters, that have a nonlinear voltage current characteristic as shown in Fig. 9.2. In normal voltage the arrester is open circuited, however when surges in voltage occur, the arrester is short circuited to pass the current and protect the equipment. Arresters are applied both at the transformer side(s) and also the circuit breaker side(s) to protect the circuit breakers when it is in the open position and during its opening.
FIGURE 9.1 A simple surge arrester.
Practical Power System and Protective Relays Commissioning. DOI: https://doi.org/10.1016/B978-0-12-816858-5.00009-5 © 2019 Elsevier Inc. All rights reserved.
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Practical Power System and Protective Relays Commissioning
FIGURE 9.2 Zinc oxide surge arrester.
9.2 TESTING OF SURGE ARRESTERS Leakage current measurements are shown in Fig. 9.3. It (Amp) is calculated by: It 5 Ic 1 Ir
FIGURE 9.3 Leakage current measurements.
Surge Arresters Theory Testing and Commissioning 9.1 INTRODUCTION A surge arrester protects system equipment such as transformers and transmission lines from excessive voltage and/or overvoltage caused by lightning or switching surges. The old design was a gap in series with a nonlinear resistor all enclosed in porcelain cover for protection. The resistance is very low at high voltage and high for low voltages; during high voltages the gap sparks over to protect the equipment, as shown in Fig. 9.1. A new design uses zinc oxide for surge arresters, that have a nonlinear voltage current characteristic as shown in Fig. 9.2. In normal voltage the arrester is open circuited, however when surges in voltage occur, the arrester is short circuited to pass the current and protect the equipment. Arresters are applied both at the transformer side(s) and also the circuit breaker side(s) to protect the circuit breakers when it is in the open position and during its opening.
FIGURE 9.1 A simple surge arrester.
Practical Power System and Protective Relays Commissioning. DOI: https://doi.org/10.1016/B978-0-12-816858-5.00009-5 © 2019 Elsevier Inc. All rights reserved.
103
104
Practical Power System and Protective Relays Commissioning
FIGURE 9.2 Zinc oxide surge arrester.
9.2 TESTING OF SURGE ARRESTERS Leakage current measurements are shown in Fig. 9.3. It (Amp) is calculated by: It 5 Ic 1 Ir
FIGURE 9.3 Leakage current measurements.