联网型风机盘管控制器_风机盘管控制器接几根线

1 Summary

1.1 INTRODUCTION

With the constant development of China's economy, a high degree of information-based society, the new high-tech technology lied to all aspects of making intelligent has become a development trend. Tend to be intelligent automation system equipment from the start. In this paper, we present for the graduation project "intelligent small central air-conditioning," explained PLC control of Intelligent Design and central air-conditioning (Freezing Point) systems.

1.2 system and process Introduction

Is introduced as follows: We he this in the design, there are two central air-conditioning system, cooling water pump from the Big Three, three chilled water pump, a cooling tower fan, two chiller comprising two sets of major equipment such as refrigeration system (due to system Small, large power cooling towers, laboratories, etc., the system of the usual two sets of refrigeration system different from the two chiller only choose a cooling tower, roved by the calculation, this does not affect their performance) is one chiller Complete sets of equipment manufacturing plant supply. According to this design laboratory requirements, we selected the five full-2 * closed compressor chiller. It is based on general principles and laws of the air-conditioning, such as automatic control by the microprocessor. Chiller from the compressor, condenser and evaporator components. Compression of the refrigerant compressors, compressed into the refrigerator condenser, cooling water cooling, a liquid, precipitation heat away from the cooling water and cooling Tarja discharged into the atmosphere. Liquid refrigerant from the condenser into the evaporator evaporation absorb heat, chilled water cooling and chilled water fan coil absorbed into the cold air in the heat. This cycle of it, to bring out the indoor heat to reach the objective of reducing the ambient temperature. Therefore, the central air-conditioning refrigeration system for process control requirements:

(1) for the measurement of chilled water flow and return water temperature, thus calculate the actual air-conditioning cooling load, according to the actual cooling load chiller to determine the number of Taiwan Open, the best energy-sing status.

(2) the procedures for equipment linked: Start: cooling tower fan - cooling water pump - chilled water pumps - chiller. Stop: chiller - chilled water pumps - cooling water pump - the cooling tower fan. When one of the cooling water pump / chilled water pump failure, the backup cooling water pump / chilled water pump will automatically enter the workforce.

(3) measurement system for chilled water pipes to the pressure △ P = P1-P2 control of their bypass valve (TV) openings, to maintain the pressure.

(4) because we designed this lab aims to give students a more vivid image of the study and understanding of central air-conditioning system, so the design process, we will take into account the ropriate and important position to facilitate the installation of observation refrigeration Agent or the peep-flow situation.

1.3 PLC theory and lication

Central air-conditioning refrigeration system control are three kinds of control: the early relay control systems, direct digital controller DDC and the PLC (PLC) control system. Relay control system because of the high failure rate, the system complicated, the obvious shortcomings of higher power has been gradually eliminated by the people, direct digital controller DDC Although there he been very intelligent in the development. However, due to DDC its own anti-jamming capability and step-by-step grade structure and the limitations of limiting the scope of its lication. On the contrary, PLC control system with its reliable operation, use and maintenance are very convenient and anti-interference capability and high-speed network for the new structure of these significant advantages to gradually wide range of lications.

PLC is a computer in a family. In the last century after the invention of being, in machine tools, various lines of transportation machinery, power generation, chemical, and electronics industries of electrical control equipment has been widely used, early PLC, known as Programmable logic controller (Programmable Logic Controller), that is referred to as the PLC.

PLC is a powerful, reliable, easy maintenance, and so many advantages. The traditional relay circuit, it is difficult to achieve complex logic functions and the digital control, but also to achieve a certain amount of logic control not only the design cumbersome and difficult to upgrade and prone to failure, maintenance complex, now has been great Medium-control equipment abandoned by the system. The PLC is being widely used and he been gradually replaced the relay circuit logic control. With the leap in science and technology development, PLC also has been continuously improved and strong, while its functions and greatly exceeded the scope of control logic, such as communication and networking functions, such as self-diagnosis. So today we he such a device known as programmable logic controller, but we still referred to such devices used for PLC.