Welcome to an insightful exploration of chiller controls, brought to you by Paul from theengineeringmindset.com. In this article, we will delve into the intricacies of how a chiller’s control system operates, ensuring efficient and safe functionality.
The control box is a crucial component of a chiller, typically mounted directly onto the unit. It houses the controller and a network of wires that connect various parts of the chiller. This setup not only allows for local control but also enables remote management through a Building Management System (BMS).
On a real chiller, you’ll notice numerous cables running from different sections back to the control box. These cables play a vital role in monitoring and controlling the chiller’s operations.
The control box gathers measurements from across the chiller, which are essential for both operation and protection. These measurements are logged, either internally or externally, to help service engineers diagnose and ensure the chiller functions as intended. The logs provide a historical view of the chiller’s performance, allowing for the review of alarms, settings, and live data such as temperatures, pressures, and operational states.
To ensure optimal performance, the chiller must monitor the flow of water in both the evaporator and condenser loops. Adequate flow is crucial to prevent freezing and potential damage to the heat exchanger tubes. Flow sensors relay this information back to the control box, which will only allow the chiller to start if sufficient flow is detected.
Temperature monitoring is equally important. The chiller tracks the temperatures of the fluids in both the chilled and condenser water loops, including flow and return temperatures. Additionally, the behavior of the refrigerant is closely observed, with measurements taken for pressures and temperatures at various points in the system, such as the suction, discharge, and liquid lines.
Using the collected temperature and pressure data, the chiller’s performance can be plotted using refrigerant tables and interpolation techniques. The chiller employs vane guides to adjust its capacity, and these guides are controlled to meet the required cooling demands. Monitoring and controlling the vane guide actuators is thus essential.
The induction motor on the compressor is a critical component, and its monitoring is vital. The control panel measures the motor’s winding temperatures, current draw per phase, and voltage. If any of these parameters exceed safe limits, the motor is protected by limiting current or shutting down to prevent damage.
The oil sump pump circulates lubricating oil to safeguard the motor and gears. The temperature and pressure within the lubrication circuit are monitored to ensure proper operation. Many of these measurement points serve dual purposes: operating the machine and protecting it. Built-in programs will halt the machine or alert operators if parameters exceed safe thresholds, such as high pressure causing the chiller to trip.
The control panel also records the motor’s run hours and start frequency. To prevent damage from excessive inrush current, chillers are designed to start only a limited number of times per hour. Live data recordings from a real chiller illustrate various measurements, including pressures in kilopascals and temperatures in degrees Celsius. These readings cover water loop temperatures, flow detection, motor circuit voltage and current, refrigerant system pressures and temperatures, oil pump conditions, and motor winding temperatures. Additionally, the vane guide positions and compressor run hours since the last service are tracked.
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Engage in a virtual simulation of a chiller control box. You’ll be tasked with connecting various components and monitoring their interactions. This activity will help you understand the control box’s role as the chiller’s brain, managing both local and remote operations.
Participate in a workshop where you’ll analyze real chiller data logs. You’ll learn to interpret historical performance data, identify patterns, and diagnose potential issues. This hands-on experience will enhance your ability to ensure efficient chiller functionality.
Take part in a challenge to monitor and adjust water and refrigerant loops. You’ll use flow sensors and temperature data to maintain optimal chiller performance, preventing freezing and damage. This activity will deepen your understanding of the importance of flow and temperature monitoring.
Engage in a diagnostic exercise focused on the chiller’s compressor and motor. You’ll monitor parameters such as winding temperatures, current draw, and voltage. This exercise will teach you how to protect these critical components from damage.
Analyze the chiller’s lubrication system by examining temperature and pressure data. You’ll learn how these measurements ensure proper operation and protection of the motor and gears. This activity will highlight the dual purpose of these monitoring points.
Sure! Here’s a sanitized version of the provided YouTube transcript:
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[Applause] Hello everyone, Paul here from theengineeringmindset.com. In this video, we will be examining the controls of a chiller. The controls box is typically mounted to the chiller, and I’ve highlighted it in this illustration. A real controls panel will look something like this, featuring the controller and various wires connected throughout the chiller. It also allows for remote control or access via the Building Management System (BMS).
On a real chiller, you’ll see numerous cables running from different parts back to the control box. We will explore what some of these cables do and how they control the chiller.
So, why do we need the controls box on the chiller? The controls box takes measurements from all over the machine. These measurements not only help control the machine but also protect it in case of any faults. Logs are usually kept for a certain amount of time in the machine or can be recorded externally. These logs allow service engineers to diagnose the machine and ensure it operates as designed.
The logs may look something like this. While this is a static operation, you can see that you can review data from a certain period to diagnose the machine from the display unit. You can check alarms, settings, and views. The display will show live data from the chiller, including various temperatures, pressures, and states.
First, we need to know how the chiller water and condenser water loops are behaving. The chiller must detect that water is flowing in the evaporator and condenser water loops. The chiller should not start if there is inadequate flow to protect it from freezing and damaging the heat exchanger tubes. Flow sensors connected to these loops feed data back to the control box. If adequate flow is detected, the machine will be allowed to start.
Next, the chiller needs to monitor the temperature of the fluids in both the chilled water loop and the condenser water loop, including flow and return temperatures.
We also need to monitor the refrigerant’s behavior. The chiller will measure the pressure of the evaporator and condenser, as well as the temperature of the refrigerant throughout the system, including suction line temperature, discharge line temperature, and liquid line temperature.
From these temperature and pressure measurements, you can plot the performance of the chiller using refrigerant tables and some interpolation. The chiller uses vane guides to control its capacity, and these guides change position to meet the required cooling capacity. Therefore, we need to measure and control the vane guide actuators as well.
The induction motor mounted on the compressor is a vital component of the chiller, so monitoring this is essential. The control panel will measure the temperature of the windings, the amount of current being drawn by the motor per phase, and the voltage. If the voltage, current, or temperature becomes too high, the motor could burn out. Monitoring these parameters allows the motor to protect itself by limiting the current and shutting off if a fault occurs.
Another important circuit is the oil sump pump, which circulates lubricating oil around the machine to protect the motor and gears. The temperature and pressure of the lubrication circuit are also monitored.
Most of these temperature and pressure measurement points around the chiller are there not only to operate the machine but also to protect it. There are built-in programs that will stop the machine or alert the operator if pressure or temperature exceeds or falls below certain thresholds. For example, if there is high pressure, the chiller may trip and cease operation for a certain period.
The control panel for the motor records run hours and the number of starts. Most chillers can only start a limited number of times per hour to protect against excessive inrush current, which could damage circuits and components.
I have included a few screenshots from an actual chiller to show what it looks like when recording live data. All these points measure pressure in kilopascals and temperature in degrees Celsius. You can see the temperatures of the different water loops, flow detection, voltage, and current from the motor circuit, as well as various pressure and temperature sensors from the refrigerant system. This also includes monitoring the oil pump temperatures and pressures, as well as the motor winding temperatures. Additionally, you can see the position of the vane guides and how many hours the compressor has run since the last service.
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This version removes informal language and maintains a professional tone while preserving the essential information.
Chiller – A device used in engineering to remove heat from a liquid via a vapor-compression or absorption refrigeration cycle. – The new chiller system installed in the laboratory ensures that the equipment operates within the optimal temperature range.
Control – The process of regulating variables within a system to achieve desired outcomes. – Engineers implemented an advanced control system to maintain the stability of the power grid under varying load conditions.
Monitoring – The continuous observation and recording of activities or data to ensure systems function correctly and efficiently. – The monitoring of the reactor’s core temperature is crucial to prevent overheating and ensure safety.
Temperature – A measure of the average kinetic energy of the particles in a system, indicating how hot or cold the system is. – Accurate temperature measurements are essential in the manufacturing process to ensure product quality.
Pressure – The force exerted per unit area within a system, often measured in pascals or psi. – The pressure in the hydraulic system must be carefully controlled to prevent leaks and maintain efficiency.
Performance – The efficiency and effectiveness with which a system or component operates under specified conditions. – The performance of the new turbine was evaluated to ensure it meets the energy output requirements.
Capacity – The maximum amount that a system or component can contain or produce. – The plant’s production capacity was increased by upgrading the existing machinery.
Refrigerant – A substance used in a cooling mechanism, such as an air conditioner or refrigerator, to absorb and release heat. – The choice of refrigerant significantly impacts the efficiency and environmental footprint of the cooling system.
Lubrication – The application of a substance to minimize friction and wear between surfaces in contact. – Regular lubrication of the engine components is necessary to ensure smooth operation and extend their lifespan.
Data – Quantitative or qualitative values collected from observations or experiments, used for analysis and decision-making. – The data collected from the sensors were analyzed to optimize the design of the new aerodynamic model.
