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SPD Selection

Feb 18, 2017

Protection based on the SPD wants to achieve the desired results, should pay attention to "in the right place the right to install the appropriate SPD" lightning protection device of choice is very important.
1. Enter the building between the various facilities of lightning current distribution is as follows: about external lightning discharge lightning current into 50%, another 50% of lightning current within the whole system of metal material for distribution. * The models were used to estimate the value in the LPAOA area, LPZOB area and LPZ1 area for Lightning equipotential connection of the junction of flow capacity and specification of metal wire. 10/35 μ s the lightning current waveform. In the lightning current distribution in the metal case: the partial lightning current amplitude depending on the distribution channel impedance and reactance, distribution channel is something that could be assigned to the current metal material, such as power lines, signal lines, water pipes, metal frame metal tube level and it grounded, only with the individual earthing resistance value can be estimated roughly. In the case of uncertainty, can be considered to be equal to the resistance, namely metal pipe evenly distributed current.
2. introduced in the overhead power lines, and power lines could be hit by lightning when entering buildings within protected areas of lightning current depends on the external lines, lightning discharge branch and user-side line impedance and reactance. Such as internal and external impedance at both ends, the power line was assigned to half the direct strike lightning current. In this case must be used with anti-direct lightning lightning.
3. * subsequent * estimated model LPZ1 protection zone at the junction after the lightning current distribution in the region. User side insulation resistance is much greater than lightning discharge branch and the impedance of the drainage lines, into the subsequent lightning lightning current will be reduced, in the estimation of value without any special. General requirements for the subsequent lightning power supply flow capacity at 20kA (8/20 μ s), do not need large capacity surge protector.
Lightning protection lightning protection device of choice for follow-up should be considered at all levels between the energy distribution and voltage support, many factors it is difficult to determine when to utilize-and power supply is a good choice. Series and is based on modern lightning protective in many applications, the concept of differentiated characteristics, such as the scope of protection (as opposed to traditional and SPD). Its essence is the energy cooperation and voltage-distribution of multiple appliances and the combination of the filter. And mine has the following characteristics: wide range of applications. Not only can be applied in a conventional manner, indistinguishable places also suitable for protected areas. Induced decoupling device in transient over voltage under voltage, delay effects, to help achieve energy cooperation. Slow the rising rate of transient disturbance to achieve low residual voltage with long life and fast response time.
4. lightning protection with additional parameters depends on the individual mine levels, its voltage to rated voltage of all components installed in the circuit shall prevail. And note also that the rated current of lightning.
5. other factors affecting the electronic line of lightning current distribution: transformer terminal of grounding resistance reducing the current increase is allocated will make electronic wire. Increase in length of power supply cables will reduce distribution of current in the power line, and make a few to balance distribution of current in the wire. Short cable lengths and low neutral wire resistance causes a current imbalance, resulting in a differential mode interference. Power cable and user will reduce the effective impedance, resulted in the allocation of current increases, connect into a network of power supply condition, Ray temporary flow mainly into power line, which is the cause of most Thunder loss occurs in the line.