Why should fuse be added to surge protection device?

Promulgator : TAIXIDate : 2017-06-09Views : 58

Why should fuse be added to surge protection device?
1. To prevent damage to SPD and its lines due to lightning strikes (for discharge gap type devices).
2. Easy maintenance and replacement SPD.
3. To prevent the line due to SPD aging (such as mov device leakage increases) caused by line failure
SPD front-end fuse should be installed according to the arrester manufacturers parameters.
Such as manufacturers do not provide, generally choose the principle:
According to the maximum fuse strength A of the surge protector and the maximum supply current B of the connected distribution line (the open circuit current C of the switch or fuse).
Determine the method:
When: B is greater than A, C is less than or equal to A
When: B is equal to A, C is less than A or does not install C
When: B is less than A, C is greater than or equal to A

Note: Energy consumption indicators of the surge protection device (SPD)
1. SPD only in the case of surge action, in the normal case is equivalent to the insulator, the power consumption of about 1W, the application of the case is not the image.
2. The arrester has no energy consumption parameter.
Because mov (pressure sensitive) type leakage current, should consume power.
Three-phase SPD is installed between L, N and PE so the calculation is as follows:
Single module: P = UI × cosφ = 220 × 30 × 0.000001 = 0.0066 watts U is the voltage, phase current, cosφ take 1.
Three modules: P = 3 × UI × cosφ = 3 × 220 × 30 × 0.000001 = 0.0198 W
MOV current flowing through the valve at nominal nominal operating voltage is called the leakage current. According to national standards should be less than 30μA. The rate of change before and after the impact should be less than 200%.