I. Introduction

Fans and pumps are a kind of general-purpose machinery, which is widely used in various fields such as industry, agriculture and life. At the same time, various design codes also have corresponding specific requirements for the control and protection of fans and pumps in different situations in the construction field. With the rapid development of the construction industry, building automatic monitoring systems (BAS, Build Automatic Monitor System) are also commonly used in buildings and large-scale public building construction projects.

2. Intelligent controller

The intelligent controller uses the 32-bit ColdFire V1 core MCF51EM256 processor introduced by Freescale as the control core, 4 channels of 16-bit SAR ADC, 3 SPI, 3 SCI and 1 I2C interface, 3 timing module hardware, independent The RTC clock and two LASH memories, abundant GPIO ports, and abundant CPU Katayama resources ensure the reliability and advancement of the module.

The controller integrates measurement, protection, control, and bus communication. It replaces the original protection relays, electrical measuring instruments, changeover switches, buttons and signal indicators that are configured with separate components. It integrates direct start, star-delta start, etc. Various control methods. At the same time, it provides records of important management information such as operation times, running time, and trip events. The bus communication function can carry out data exchange and remote control with the management system, which improves the intelligent level of the building and simplifies the traditional control cabinet design.

3. Fan control scheme

The National Standard Design Atlas "Commonly Used Motor Control Circuits" (10D303-2) collects the control circuits of commonly used fans in buildings, including exhaust fans, dual-purpose single-speed fans, exhaust and smoke dual-use dual-speed fans, etc. This kind of scheme is convenient for electrical designers to design and improve work efficiency. However, with the introduction of building energy-saving requirements and building equipment monitoring system technical specifications, the control scheme using the original atlas discrete component method can no longer meet the requirements of equipment upgrades and the requirements of the monitoring system for equipment monitoring content.

3.1 Principle of ordinary fan control

The standard requirements for the linkage of ordinary fans and electric dampers are: "All AC motors should be equipped with phase-to-phase short-circuit and ground fault protection, and overload, phase-out and low-voltage protection should be installed according to specific conditions." When the fan starts, the damper opens: return to manual/automatic mode to DDC, receive DDC control signal in automatic mode, protect against short circuit or overload failure during operation, indicator light alarms, and return fan failure signal to control point .