The general requirements for selecting gapless metal oxide arrester manufacturers are as follows:
(1) The environmental conditions for the use of arresters should be determined according to the temperature, altitude, wind speed, pollution and earthquake conditions in the area of use, and the system operating conditions of the arrester should be determined according to the nominal voltage of the system, the highest voltage of the system, the rated frequency, the neutral point grounding method, the short-circuit current value and the duration of the ground fault.
(2) Determine the type of arrester according to the object to be protected.
(3) Determine the continuous operating voltage of the arrester based on the highest voltage acting on the arrester for a long time.
(4) Select the rated voltage of the arrester according to the temporary overvoltage amplitude and duration of the arrester installation location.
(5) Estimate the amplitude of the discharge current passing through the arrester and select the nominal discharge current of the arrester.
(6) Determine the lightning overvoltage protection level and operating overvoltage protection level of the arrester based on the rated lightning impulse withstand voltage and rated operating impulse withstand voltage of the protected equipment and the insulation coordination requirements.
(7) Estimate the impulse current and energy passing through the arrester, select the test current amplitude of the arrester, the cold shrink cable terminal line discharge withstand test level and energy absorption capacity.
(8) Select the pressure release level of the arrester according to the maximum fault current at the place where the arrester is installed.
(9) According to the degree of environmental pollution at the place where the arrester is installed, select the leakage ratio of the porcelain sleeve of the arrester.
(10) Select the mechanical strength of the arrester according to the lead wire tension, wind speed and earthquake conditions of the arrester installation.
(11) When the arrester does not meet the insulation coordination requirements, remedial measures such as appropriately reducing its rated voltage or nominal discharge current level or improving the insulation level of the protected equipment can be taken.
