1. Reactive maintenance One approach that is still frequently used is reactive maintenance, where machines or plants are only repaired in the event of failure or defect. 2. Preventive maintenance With preventive maintenance, machines or plants are shut down at defined intervals to check and, if necessary, replace used components. Parts are inspected for wear in order to increase the lifespan and availability of the machine. This type of maintenance often results in fully functional components being replaced before their full service life has been utilized. The cost of preventive maintenance eats into a considerable share of profits at many companies. 3. Condition-based maintenance The goal of condition-based maintenance is to utilize information about the condition of production equipment in order to optimize the scheduling of maintenance work, ultimately resulting in maximized production quality and minimized maintenance costs. Precise and continuous measurement Modern instrumentation makes it possible to record, determine and assess the condition of machines and systems continuously and with a high degree of precision. This information helps identify potential sources of malfunction and damage in advance so that corrective action can be scheduled for a time when it is convenient instead of an emergency situation.
Exploit full useful life You can get value out of components for nearly their entire useful life – while eliminating the majority of primary (and therefore also secondary) damage. Simple and affordable solutions prevent failure Early detection of damage, through vibration analysis for example, helps to prevent total system failure. VDI 2888 provides guidelines for users VDI Guideline No. 2888 provides potential users with a manual on how a company can introduce condition-based maintenance. Condition monitoring defined in VDI/VDE 2651 (Plant Asset Management (PAM) in the process industry) VDI/VDE Guideline No. 2651 (Plant Asset Management (PAM) in the process industry) defines condition monitoring as involving the measurement and analysis of an asset's condition. Condition monitoring has established itself predominantly in the field of rotating equipment. In order to avoid misunderstandings, it is important to define the assets or asset categories to which condition monitoring applies. "An ounce of prevention" Those who follow the adage "an ounce of prevention is worth a pound of cure" will be well prepared to face the constantly increasing demands for more safety, availability and efficiency.
4. Predictive maintenance Intelligent maintenance that begins long before a machine or system malfunctions is called predictive maintenance. Advanced technology and analytical models allow operators to detect complex patterns and predict unplanned events. In order to be effective, predictive maintenance techniques must be based on large volumes of heterogeneous data. Data aggregation and data mining Hundreds of detailed parameters from a variety of sources are aggregated and analyzed. Data mining techniques are used to examine historical data to uncover previously unrecognized – and often very complex – causal relationships. In combination with production data and information from sensors, the probability of malfunctions becomes predictable. This knowledge can be used to make more informed maintenance decisions, such as deferring tasks of lower importance to allow for prompt replacement of components where failure is imminent. It also allows for proactive identification of systematic error patterns and their root causes.
Maintenance strategy trends
Reactive/Preventive maintenance on the decline The prevalence of reactive maintenance (unplanned downtime, secondary damage) and preventive maintenance (useful life not exploited) is declining in favor of condition-based and predictive maintenance. Stark differences between industries In some areas, reliance on reactive and preventive maintenance has been fading for decades, while in others progress stagnated many years ago.
Degree of automation vs. maintenance costs
Shift in relative costs Looking at relative costs, the clear trend is that personnel costs (maintenance personnel excluded) sink as the degree of automation increases. Maintenance costs rise At the same time, we see that the more complex the system, the higher the maintenance costs (maintenance, inspection and repairs). The additional expenses for maintenance, however, are more than compensated by the reduction in personnel costs. Significance of maintenance rises with degree of automation The inescapable conclusion is that the importance of maintenance, which is already quite significant, will continue to grow as a company increases the degree of automation used in its Material Personnel equipment.
Advantages of condition-based maintenance
Timely detection of primary damage helps prevent secondary damage
"Built-in safety" helps protect human operators and the environment
Knowing the current state of the system helps more accurately predict achievable product quality and production quantities
Components provide value for more of their useful life
The mean time between maintenance is increased
The majority of needless repair work is prevented
Spare parts inventory can be streamlined
More advanced notice of repairs allows for more convenient downtime planning
Knowledge of wear levels improves operational safety
"Built-in" safety allows operators to focus on core responsibilities
Plant Asset Management (PAM)
VDI/VDE Guideline No. 2651 "Plant Asset Management (PAM) in the process industry" divides the main tasks of PAM into three categories:
Monitoring, diagnosis, prognosis and therapy
Provision and storage of information
Analysis, presentation and dissemination
Main tasks involved in Plant Asset Management (PAM) in the process industry in accordance with VDI/VDE Guideline No. 2651.
Monitoring, diagnosis, prognosis & therapy
Performance monitoring of production plants, sub-plants and plant components by means of indicators. This includes control performance monitoring of feedback control loops and associated assets.
Asset indications with user-dependent display and administration as well as monitoring of process alarms (number of alarms, number of alarms/unit of time, priorities, etc.).
Condition monitoring (CM) serves the purpose of monitoring the condition of an asset (CM for pressure gauge sensors, CM for centrifugal pumps, etc.).
Signal monitoring deals with the recording and processing of signals and subsequent analysis of attributes.
Functional testing includes initiation and execution of inspections to ensure the functional reliability of assets (e.g. partial stroke test for safety valves).
Condition diagnosis is the evaluation of symptoms to make a diagnosis.
Maintenance requirements are formulated based on diagnosis and prognosis functions. Includes documenting maintenance requirements and making them available.
Prognosis of performance is the predicted development of an asset's condition based on the latest condition diagnosis.
Determination of wear tolerance refers to the deduction of the remaining useful life of an asset based on past and present asset information.
Suggestion of therapy involves the deduction of suitable measures to establish the required function of the asset.
Performance optimization includes initiation of measures to optimize the performance efficiency of an asset.
Condition monitoring systems
Condition Monitoring Systems (CMS) are described as systems that monitor the condition of machines and systems.
The primary goal of a CMS is to gather and relay the current condition of a system as well as to provide advanced detection or prediction of damage. In order to achieve these goals, the system must provide the following functionality:
Measurement, storage and compression of condition parameters
Online monitoring of parameters
Online linking of parameters
Evaluation of measurement data
Incorporation and processing of additional data
A CMS measures dynamic condition parameters such as torque and vibration Unlike a standard monitoring system, a CMS measures, stores and compresses not only quasistatic parameters such as temperature, pressure, motor current, power and speed, but also dynamic parameters like torque and vibration. These dynamic parameters can provide insight into the progression of wear and tear as well as the load on the machine or system. The data gathered by the CMS represents a valuable source of information for maintenance planning. Condition monitoring systems are primarily used in the areas of vibration monitoring (oscillations, structure-borne sound), current consumption, pressurized air consumption, torque measurement, thermal imaging and oil analysis.
Increased vibration usually caused by imbalances Vibration analysis is based on the principle that all mechanical processes involve the transmission of forces that are ultimately conducted to the surface of the structure. Frequently, an increase in the vibrations produced by machines with rotating masses is an indication of a mechanical imbalance. Such an imbalance can result in increased wear and eventually damage to bearings, rotating parts, the frame of the machine or even the building itself. In ventilation systems, imbalances may be caused by deterioration or build-up on the rotor blades. Parts that are loose, misaligned, come into contact with other parts or don't fit properly also cause increased vibrations. Fast Fourier transform for identifying characteristic frequencies After the vibration signal is recorded, a fast Fourier transform is used to break it down into its components, whose values are then analyzed. Doing so allows characteristic frequencies to be identified that would not occur in optimal conditions. The calculated RMS value of the component signals serves as a reference for determining the existing degree of damage. If the kinematic properties of the machine are known (number of teeth on gears, type of roller bearings, speed, etc.), then it is also possible to identify the damaged components.
Parameters used for condition monitoring
Level of impurities
Startup and shutdown
Vibration and noise
Quantity of waste products
Operating resource consumption
Standalone solution for measurement and monitoring in all industries
APROL ConMon is B&R's solution for measuring, recording and evaluating all relevant condition parameters to provide optimal support for the continual improvement process.
Measurement, storage and compression of condition parameters
Online monitoring of parameters
Online linking of parameters
Evaluation of measurement data
Incorporation and processing of additional data
Flexible integration into existing automation solutions APROL ConMon can be used as a standalone solution – independent of any existing building control systems, SCADA systems, process control systems and PLC solutions – or it can be integrated into an existing APROL process control system. APROL ConMon – An optimal solution for all industries APROL ConMon can be customized to monitor a single machine, an entire factory, a building, a process or a plant.
Machine automation When a new series-produced machine is developed, highly effective equipment is needed in order to measure, record and evaluate all of the relevant parameters. APROL ConMon provides optimal support in this task.
"Black box" for machine builders Another interesting application of the standalone version of APROL ConMon is as a "black box" for an OEM to reliably and seamlessly monitor whether the user operates the machine in accordance with specifications during the warranty period.
Plant automation The typical plant automation application is a mid-sized plant with multiple controllers. Since condition monitoring is generally also used to protect the individual components as well, the optimum solution in this case is integration into the overall APROL system.
Process automation When an APROL process control system is already in use, integrating ConMon has the added benefit that all system functions have full access to the condition monitoring data. With an existing third-party process control system, condition monitoring is generally implemented via separate systems of sensors and evaluation electronics. These systems can be connected via interfaces to display their data in the third-party process control system. Detailed analysis of vibration measurements can be performed directly in the standalone version of APROL ConMon.
Factory automation Factory automation often requires collection of additional condition monitoring data for individual machines. These measurements are obtained from additional remote I/O modules and then processed in a separate APROL ConMon system.
The ready-to-use APROL ConMon solution is based on the APROL process control system to ensure maximum flexibility with very little engineering. It also makes the implementation of Condition Monitoring Systems (CMS) and Plant Asset Management (PAM) tasks considerably easier. With APROL as the platform, it is also possible to implement solutions that go far beyond conventional condition monitoring tasks. Because of its outstanding scalability, the system can grow to meet new demands, ensuring exceptional long-term investment protection. System topology An APROL ConMon system consists of an Automation PC 910 situated in a control cabinet. It includes the complete system with all necessary software preinstalled. In addition to the engineering and operator software, the system also includes a high-performance database with an SQL interface. It is based on the extremely stable SUSE Linux Enterprise Server operating system. All required data is archived. Usually installed in the control cabinet without a monitor, the APC910 can be accessed over the network from workstation computers using a web browser or VNC client. There is no need to install additional software. A controller is required in order to read the condition monitoring data from the I/O modules and to preprocess these values. Depending on the number of I/O points, it is possible to add many more controllers. The controllers and I/O modules communicate via POWERLINK. When using existing bus cabling, Modbus TCP or PROFIBUS DP are also possible alternatives.
APROL ConMon system structure
Broad range of products for measuring condition parameters
Vibration metering and analysis using metering module for condition monitoring
Electrical power using metering module for electrical power
Runtime, downtime, etc. using binary input module
Pressure, flow rate, etc. using analog input module
Temperature (PT100, PT1000, thermocouples) using analog input module
Speed, quantity, etc. using counter module
Counter states for volume/mass flow rate using M-Bus master
Counter states for volume/mass flow rate and energy by connecting field devices via Modbus RTU, ModbusTCP, PROFIBUS DP and EtherNet/IP
Switching loads / E-stop using digital output module, either manually or via logic
Relevant operating data from ACOPOS drives via fieldbus interface
Manual entry of maintenance parameters (time intervals, maximum runtime, etc.) or reading measured values (lab measurements, etc.) using faceplate
Measuring condition parameters
Condition parameters are measured using extremely compact X20 I/O modules. The following modules are available:
Vibration metering and analysis X20CM metering module for condition monitoring tasks with 4 IEPE analog inputs, 51.5625 kHz sampling frequency and 24-bit converter resolution
Electrical power metering X20AP energy metering module for active, reactive and apparent power; records phase sequences, individual phases and cumulative values; current over neutral line; records frequency and harmonics (up to the 31st harmonic)
Binary signals for runtimes/states X20DI digital input module for runtime, downtime, etc.
Analog signal for pressure, flow rate, etc. X20AI analog input module for analog measurement signals
Analog signal for temperature X20AT analog input module for PT100, PT1000, thermocouples
Count pulses for speed, quantity, etc. X20DC digital counter module for digital measurement pulses
Counters for volume/mass flow rate X20CS interface module with integrated M-Bus master for connecting up to 250 M-Bus slaves (e.g. counters for gas meters, electricity meters, heat meters, pulse counters)
Counters for volume/mass flow rate, energy X20IF interface module for connecting Modbus RTU, ModbusTCP, PROFIBUS DP, EtherNet/IP (e.g. counters for existing measurement points)
Switching loads / E-stop X20DO digital output module or X20IF interface module for connecting or disconnecting loads either manually or via logic
Manual entry of time intervals, maximum runtimes, etc. Manual entry of various maintenance parameters or manual reading of measured values (lab measurements, etc.) via faceplate
Operating data from ACOPOS drives All relevant data read via fieldbus interface
Control modules for APROL ConMon
The user can select from a comprehensive library of powerful control modules.
1. Reading binary states A control module for reading binary states is used primarily to create and log messages and alarms. Configurable switch-on delays, switch-off delays and a latch allow this module to be adapted to specific applications. The signal state of the input and output is automatically plotted as a trend curve.
2. Time, operating hours and operating cycle counter A control module is available for reading startup and shutdown times, runtimes, downtimes, cycle times, warm up times, etc., and for generating alarms and messages. Additionally, the time between the output of a command and the receipt of feedback is measured and recorded. The control module records data in two logical directions (open/closed, right/left, etc.) as well as calculating their sum total.
3. Monitoring quantity (analog interface / pulse counter) The "Totalizer 01" control module is used to measure process parameters such as use of operating resources, energy consumption, production quantities, waste quantities and more. It provides precise integration of analog measurements (such as flow rate) as well as pulse counting (forward, backward). Leakage suppression and monitoring rate of change (up/down) can also be configured. The signal state for the forward counter, backward counter, and the resulting sum counter are automatically plotted as a trend curve.
4. Monitoring process parameters The "Analog Monitor" control module is used to measure process parameters (mechanical, thermodynamic, analytical, etc.) such as torque, rotary speed, pressure, velocity, temperature, composition and impurities. It supports monitoring of up to 6 limits for analog values (e.g. temperature) as well as monitoring of rate of change (up/down). A configurable filter is also integrated. The signal state of the input (raw value) and the effective value are automatically plotted as a trend curve.
5. Monitoring of vibrations The "CondMon" control module is available in addition to the module for vibration metering and analysis (amplitude and frequency). The 4-channel structure of the metering module is mirrored in the faceplate.
Five statistical parameters can be displayed For a selected channel, up to five statistical parameters and the velocity assigned to the channel can be displayed in addition to the measurement signal itself (velocity or acceleration).Velocity and acceleration for the configured frequency domain are recorded on the metering module and output as primary measurement values.
Parameters for direct condition evaluation In addition, statistical parameters are calculated, such as vibration severity in accordance with ISO 10816. It is often possible to draw conclusions about the condition of the machine based on these parameters alone, without any further analysis of frequency characteristics, and display the results in the form of a traffic light symbol. Preprocessing in the metering module In standard applications, the raw signal is completely preprocessed within the metering module, with velocity, acceleration and statistical parameters output via the I/O channels.
Amplitude signal For more detailed analysis, the "ConMon" control module can be used to access the amplitude signal (change in amplitude of acceleration over the course of the measuring period) as either a raw value or an envelope. Data is read sequentially from the module and stored in the trend archive. Amplitude spectra Like the amplitude signal, it is possible to access the amplitude spectra produced via FFT in the metering module as either a raw value or envelope. Trigger manually or via logic Saving amplitude signals and amplitude spectra in the trend archive can be triggered manually or by logic.
Amplitude signal A curve showing the change in acceleration amplitude over the course of a measurement period (either as a raw value or envelope) allows for a detailed analysis to identify the source of the vibration.
Display amplitude spectra The display of amplitude spectra makes it easy to identify individual disturbance frequencies and accurately attribute them to potential sources.
Monitoring with 32 frequency bands The 32 frequency bands can assigned to the 4 channels as needed.
Configuration overview All essential configuration information is grouped by channel on the faceplate.
Reference values for performance monitoring Once a machine or system has been commissioned and its optimal operating state established, a number of baseline statistical values can be stored directly on the module and compared against current vibration data over the course of the machine or system's life cycle.
6. Monitoring electrical values with the X20AP energy metering module The "EngyMon01" control module can be used in addition to the metering module for electrical power in order to read energy consumption process parameters.
Including the harmonics Unplanned outages of machines, systems or individual consumers can result not only from increased energy consumption, but for other reasons as well. Due to the use of countless inverters in every possible area nowadays – not least in order to save energy costs – the resulting harmonics play a large role in diminishing power quality in electrical grids. These harmonics must be taken into consideration when measuring energy in order to achieve sufficient precision. Because of this, they are covered up to the 31st harmonic.
Monitoring the mains frequency Unexpected failure of electrical components, especially in isolated operation, can also be prevented by measuring the mains frequency with a precision of 0.01 Hz.
Detecting imbalances Measuring current via the neutral line can help detect imbalances on the consumer brought about by short-circuited coils, for example, which makes it possible to avert resulting malfunctions by carrying out targeted measures in a timely fashion.
Detection of reactive load on the consumer Preventing reactive current reduces energy consumption and decreases the load on the mains power supply. Targeted measurement of reactive and apparent power helps identify the cause right at the source.
Identifying sluggishness through reference curves Measuring motor current is a simple and reliable way to monitor the sluggishness of an electric motor. Changes in current consumption point to increased sluggishness. Baseline current measurements of a reference movement during commissioning (reference curve) can help visualize the change in sluggishness over time in a trend curve.
7. Energy and flow calculation for water and steam in accordance with IAPWS-IF97 APROL ConMon also includes the "PowerCalculation" control module for thermodynamics (enthalpy) to directly calculate the thermal power/energy of water, saturated steam and superheated steam in accordance with IAPWS-IF97. It records incoming and outgoing energy currents of water, saturated steam and superheated steam, and their differences. This control module eliminates the need to have expensive computers dedicated to energy unless absolutely required for calibration certification.
"PowerCalculation" control module This module is used to calculate thermal power/energy from one or two meter runs in accordance with IAPWS-IF97. The incoming and outgoing energy currents of water, saturated steam and superheated steam, as well as the heat exchanged with the outside environment, are calculated and displayed by the "PowerCalculation" control module.
8. Flow measurement in accordance with EN ISO 5167 (-2,-3,-4) The "FlowCalculation" control module calculates the rate of flow in pipes with a circular cross section in accordance with ISO 5167-2 (orifice plates), ISO 5167-3 (nozzles and Venturi nozzles) and ISO 5167-4 (Venturi tubes). A high degree of precision is achieved by calculating the mass flow rate using Newton's method and taking the flow speed and Reynolds number into consideration.
Control performance monitoring for control loops
Manual mode ensures stable operation It is a well-known fact that PID controllers are generally not configured optimally and must therefore be operated manually at least some of the time. Plant operators are also not able to monitor the control loops allocated to them 100% of the time. This can only be achieved with integrated process control system functionality.
Creeping degradation Monitoring control quality helps automatically detect creeping degradations of control loop performance so that appropriate maintenance measures can be taken or control parameters optimized.
Statistical parameters identify tendencies The "CPM01" control module provides various statistical parameters that can be used to assess the quality of control loops. These parameters are crucial for achieving maximum process control efficiency. Even APROL APC (Advanced Process Control) solutions are fundamentally dependent on the quality of lower-level automation. The basic idea is to provide and display data that is relevant to the control loop. The calculated parameters must be interpreted by the user. The minimum variance index is thus determined by comparing the variance of the controlled variable of the controller being used with the variance which would occur through the use of a minimum variance controller.
CPM01 control module This module calculates the various statistics needed to assess the performance of control loops. Input data for control performance monitoring The setpoint (W), manipulated variable (Y), controlled variable (X) and operating mode (manual/auto) must be provided in order to allow the non-invasive calculation of continuous and condition- based parameters.
Continuously calculated parameters These include parameters such as integral absolute error, integral squared error, standard deviation of the setpoint and control error, average value of the manipulated variable, standard deviation of the manipulated variable and the controlled variable, number of controlled variable setpoint crossings and display of the process limit (manipulated variable saturation). Parameters calculated based on condition These include parameters such as the percentage of time the controller has been operated in automatic mode ("ServiceFactor"), the system's dead time, the minimum variance index and control performance indexes (difference between optimal and current evaluation criteria).
APROL ConMon configuration
APROL ConMon configuration in a few easy steps Since APROL ConMon is designed as a ready-to-use condition monitoring solution and comes preinstalled, there is no added time or cost of installing the APROL system software. The entire hardware configuration is also included; all the user has to do is adjust the network settings as needed (IP addresses, hostnames, etc.). Hardware topology in Automation Studio A controller for recording relevant measured values is a standard component in every APROL ConMon system. The hardware topology depends on customer requirements and is the first thing to be configured in the integrated Automation Studio project. Define the measurement points in a spreadsheet The second step involves defining the measurement points and associated parameters, as well as assigning the necessary templates to the sensors. This data is subsequently used to automatically generate all of the programs used to record, process and archive measurement data. Depending on the I/O and control modules used, the generated programs may require some parameter adjustments.
Configure, validate and download The third step comprises the automatic validation and any error output from all of the project elements (user software) before downloading to the APROL ConMon system (controller and control computer).
APROL ConMon operator station APROL ConMon provides the user with an intuitive user interface. In addition to the operator station, a web-based reporting environment with a dashboard landing page is available. In addition to this interface, APROL ConMon also provides a powerful environment for system diagnostics and operation for special tasks usually handled by measurement and control engineers (e.g. commissioning, maintenance).