| Recently, large marine engineering technology and equipment have been concerned,some large ocean fishing vessels were also equipped with advanced fishing installationswhich were eliminated by the developed countries and the expenses of these introductionsare extremely expensive. Currently, the fishing installations used in China commonlyconsisted with vacuum pump, fishing tank, electrical control cabinet, reversing valve, fishintake pipe and fish exhaust pipe. A vacuum pump generated the airflow which formed anegative pressure in the fish tank, then fishing catches were taken in the fishing tank by thepipe under the airflow suction effect. When fishing catches cumulated to a given number,the installation would stop, just open the valve, which was on the bottom of the fishing tank,fishing catches can be removed. However, current electrical control cabinet was equippedwith relay control system, such as relay, contactor, button, limit switch, et al. Relay controlsystem has many contacts, its wiring line was complex, and the contacts were easy to beworn, which was caused bad connect, as a result, it had a high failure rate. Increasing orchanging the function of the relay control system were very difficult, the number of relaycontacts were also limited.In this paper, we designed a fishing installation system for fishing vessels basedcurrent relay control system and PLC. The main contents were as follow: firstly, weintroduced the domestic and international development situation of fishing installation,common fishing pump and the meaning of this study. Meanwhile, we compared thedifferences between them. Secondly, with the practical surveys, we understood thestructures about the fishing installation, analyzed its work flow and make sure the worktask of every process. Thirdly, we did depth profiling to fishing installation with currentrelay control system, then pointed out the shortcoming about it. Fourthly, we introduced thebasic situation of programmable logic controller (PLC) and divided the function of thefishing installation system into hardware and software. Then we make sure about itsfunction module, which including exhaustion control system, fish intake control system andthe fish exhaust control system. We allocated the content of each module in the system tothe I/O address of PLC. The general scheme about the hardware of control system was including PLC, the selection of sensing device type and the design of control panel to finishthe design for the whole system. Fifthly, in this part, we mainly concerned about the designof software in the control system. It must make the equipment work in the order of manualcontrol and auto control. It was most important that we should program the PLC controlsystem. It consisted of3parts: capturing the signal about each module by the sensingdevice; controlling workflow enactment of software and programming the control system.With above steps, the fishing installations can work according to the demands ofcontrolling system; it realized the automatic diagnosis, automatic intake and exhaust offishes and automatic cycle, therefore, this paper achieved the objectives and requirementsabout the fishing installations. |
