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Bms Operator Job Description Download View BuildingDownload View Building Management System- Lecture 2 as PDF for free.An actuator responds to the output signal from a controller and provides the mechanical action to operate the final control device, which is typically a valve, damper or switch.A wide range of actuators is available and the chosen actuator must address the following concerns: 1.
Matching the mechanical requirements of the controlled device; 2. Matching the characteristics of the control system, especially the output signal of the controller; 3. Opto-couplers are used to Separate DDC from Actuators What is the difference between a Relay and an Optocoupler A Relay is an electrical mechanical device used to switch an alternate voltage source. The Relay will use mechanical Isolation between Voltage sources. An Optocoupler is a semiconductor device used to switch an alternate voltage source. The Optocoupler will use Optical(light) Isolation between Voltage sources. Due to the semiconductor properities, the Optocoupler will be use for higher speeds, or more offon operations (once every 5 minutes) Controlling A control system is a device, or set of devices, that manages, commands, directs or regulates the behavior of other device(s) or system(s). Open Loop Output Depend on input and also called non-feedback controller. Output Based Predicted correlation between In and Out Closed Loop - Current output is taken into consideration and corrections are made based on feedback. A closed loop system is also called a feedback control system. Set Point or desired value, Control Element, Sensing Element, Control Function-( desired direction, Negative feedback) Feedback (close-loop) Control Controlled System Controller control function control input manipulated variable Actuator error - reference Monitor sample controlled variable PID Controller A proportional integralderivative controller (PID controller) is a method of the control loop feedback. Bms Operator Job Description Plus Integral ControlDerivative controller (DC) Control Technologies Electric Pneumatic DDC (Direct Digital Control) Electric Controls Can be analog electric or electronic controls Use a variable, but continuous, electric voltage or current to operate the control system Transmit signals quickly signals and accurately Pneumatic Direct Digital Control - DDC Direct Digital Control is a control controller constantly updates an monitoring information from continuously produces corrective changing control conditions process in which a microprocessor internal information database by a controlled environment and output commands in response to DDC Controller Inputs Information Termination Board CPU Analogs to Digital converter Program Memory CPU Digital to Analogue converter Output Information DDC Vs Conventional Controlling Many Control Sequence simultaneously Defined Programmed Instructions Different Control Strategiesreprogramming can be implemented without changing the hardware Accurate and repeatable control of set-point Accuracy will not drift over time due to lack of maintenance or mechanical fatigues Offset will reduce the performance Fine tuning possible Adaptive control capabilities ( self tuning PID loops, AIartificial intelligent Neural networks, nonlinear expert control methods DDC Controller Local Software Types of DDC controllers Fixed function Configurable Text programmable Graphic programmable Point Definition Ranging (linear, calculated, polynomial) Filtering (smoothing and debounce) Interlocks Communication options between DDC Controller and Supervisory Controller include proprietary, LonWorks and BACnet LonWorks is an open standard promoted by Echelon Corporation BACnet is an open standard promoted by ASHRAE Control Loops Proportional plus integral control commonly used Other software routines used in local control logic Minimum, maximum, average, calculator, etc. No portion of this material may be reproduced, in any form or by any means, without permission in writing Regulatory Control 2008 Pearson Education, Inc., Upper Saddle River, NJ. ![]() No portion of this material may be reproduced, in any form or by any means, without permission in writing Feedforward Control Combined with Feedback Control 2008 Pearson Education, Inc., Upper Saddle River, NJ. No portion of this material may be reproduced, in any form or by any means, without permission in writing Steady-State Optimization Class of optimization techniques in which the process exhibits the following characteristics: 1. ![]() ![]()
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