A Study on the Surge Protection of Shipboard Electrical and Electronic Devices
ABSTRACT
The surge on the shipboard is generated by an insulation breakdown, a short circuit and a switch operation, and is propagated via power, signal and communication, control cables and hull. The surge may lead to serious damage to electrical and electronic devices on shipboard. With this background, this thesis analyzed the power system of ships and carried out an experimental study on the surge protective method and device. Parallel type surge protective devices(SPD) with the 220[V] and the 440[V] rated voltage, and a series type SPD with the 220[V] rated voltage for electrical sensitive devices are designed and fabricated. A surge generator specified in IEC 61000-4-5 which can produce 8/20[us] current up to 15[kA] was fabricated to evaluate the proposed SPDs. The performance of the SPDs were evaluated by an un-powered test which applies the 8/20[us] surge current up to 10[kA] and by a powered test which superimpose a surge on the 220[V] and 60[Hz]. The maximum residual voltage of the parallel type SPD for the un-powered and the powered test were 1290[V] and 891[V], and of the series type SPD were 875[V] and 656[V], respectively. The experimental results showed that the series type SPD is more effective to protect electrical sensitive devices such as signal and communication devices since the series type SPD suppresses surge lower residual voltage than the parallel one. Also, insulation voltage of the shipboard electrical and electronic devices were compared to the residual voltage of the SPDs. The residual voltages of the SPDs were lower than the demanded insulation voltage level for the mains of the 220[V] and the 440[V]. Therefore, it was confirmed that the proposed SPDs have a sufficient performance to protect the shipboard electrical and electronic devices from surge voltages.
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