EDF TRAINING TO MNER CHARACTERISE AND MAINTAIN THE MEASUREMENT CHAIN JULY 2017 EDF Thermal Generation & Engineering Division
Characterise and maintain the measurement chain 1. 1 Introduction 2 Characterise a measurement chain 3 Maintain a measurement chain 4 Example of organisation in a powerplant EDF I 07/2017 | 2
INTRODUCTION Cédric CHALAUD (cedric.chalaud@edf.fr) 5 years in a dispatching ~ 48 (1) GW 5 years Instrumentation and control in a Powerplant in Germany (EnBW) 5 years engineering and maintenance I&C for the nuclear powerplant 4 years Maintenance Instrumentation & Control (I&C) for the thermal powerplant EDF I 07/2017 | 3
INTRODUCTION Definition of a measurement chain I/O Card Monitoring Sensor EDF I 07/2017 | 4
INTRODUCTION How to define a measurement chain : Define a measurement chain = define the process which is followed The hardware architecture of the measurement chain is a compromise between Availability of the measurement (how long and how often is it acceptable to have a no “acceptable” data) Easiness to maintain Price (conception and maintenance) With this compromise, we can define the acceptable time to detect and solve a default (MTR) For the process , determine the acceptable level of uncertainty for the measurement (Quality of the measurement). That’s mean the difference between the real value and the value read EDF I 07/2017 | 5
Characterise and maintain the measurement chain 2. 1 Introduction 2 Characterisation of a measurement chain 3 Maintain a measurement chain 4 Example of organisation in a powerplant EDF I 07/2017 | 6
CHARACTERISATION OF A MEASUREMENT CHAIN 1) Hardware Architecture : one sensor for the measurement 0 sensor out OK Sensor => Repair OK 1 sensor out STOP Sensor Advantages : Inconveniences : - Easy to install - Bad rate of disponibility - Cheap - Not suitable for a safety system | 7
CHARACTERISATION OF A MEASUREMENT CHAIN 1) Hardware Architecture : 2 sensors for the measurement 0 sensor out OK Sensors 1 sensor out => Priority availability OK => Repair OK => Priority security Sensors 2 sensors out STOP => Repair OK Sensors Advantage: Inconvenience : - Suitable for a best rate of - Not suitable for a best rate of disponibility or security disponibility and security | 8
CHARACTERISATION OF A MEASUREMENT CHAIN 1) Hardware Architecture : 3 sensors for the measurement 0 sensor out => Priority availability => if 2003 values = => OK Sensors 1 sensor out => Priority security => if 2002 values = OK => Repair OK => if 2002 values ≠ Sensors => Repair OK STOP 2 sensors out Sensors Advantage: Inconvenience : - Suitable for a best rate of - Price disponibility and security EDF I 07/2017 | 9
CHARACTERISATION OF A MEASUREMENT CHAIN 1) Hardware Architecture : Important parameters for the sensors Process to follow - Temperature - Pressure - Flow - Level Parameters of the process - Temperature (normal, minimum, maximum) - Pressure (normal, minimum, maximum) - explosive atmosphere (yes / no) => ATEX - Security Level required (SIL) EDF I 07/2017 | 10
CHARACTERISATION OF A MEASUREMENT CHAIN 1) Hardware Architecture : Important parameters for the sensors Range - Difference between the maximum and minimum value of the sensed parameter Resolution - The smallest change the sensor can differentiate. - For digital sensors, it is related to number of bits used - For analog sensors, it is limited by low-level electrical noise Sensitivity - Ratio of change in output to a unit change of the input EDF I 07/2017 | 11
CHARACTERISATION OF A MEASUREMENT CHAIN 1) Hardware Architecture : Important parameters for the sensors Linearity - Percentage of deviation from the best-fit linear calibration curve Zero offset - A nonzero value output for no input Zero Drift -The departure of output from zero value over a period of time for no input Accuracy - Inversely proportional to the error - Sometimes related to the sensor’s linearity Precision - Ability to reproduce repeatedly with a given accuracy - Sometimes called repeatability EDF I 07/2017 | 12
CHARACTERISATION OF A MEASUREMENT CHAIN 1) Hardware Architecture : Important parameters for the sensors Accuracy and Precision ? Precise but not accurate Accurate but not precise Neither precise nor accurate Precise and accurate EDF I 07/2017 | 13
CHARACTERISATION OF A MEASUREMENT CHAIN 1) Hardware Architecture : Important parameters for the sensors Deadband - The range of input -for which there is no output Saturation - Maximum output capability, regardless of input EDF I 07/2017 | 14
CHARACTERISATION OF A MEASUREMENT CHAIN 1) Hardware Architecture : Important parameters for the sensors Availability - Cost - Size and available space - Ease of use - Ease of maintenance - Required signal processing - Environmental conditions - Power available for sensing Product to follow - Composition - Density - Viscosity - Concentration EDF I 07/2017 | 15
CHARACTERISATION OF A MEASUREMENT CHAIN 2) Process : Quality assurance for a measurement chain The quality assurance take into account the error of a part of the chain : Acquisition & Process Monitoring Sensor Processing 100.7 bar 100 bar 100.9 bar 101 bar Error Error Sensor Error Acquisition : 0.2% 0,7% Monitoring : 0,1% The whole error is the sum of : Error sensor + Error acquisition + Error Monitoring This method can be simplify by using only the error of the sensor (in the example, 70% of the whole error). EDF I 07/2017 | 16
CHARACTERISATION OF A MEASUREMENT CHAIN 2) Process : Define the acceptable error for the process Process Sensor I/O Card Supervision 101 bar 100 bar EDF I 07/2017 | 17
CHARACTERISATION OF A MEASUREMENT CHAIN After the characterisation of the measurement chain, we can define 4 groups for strategic chains: • Material Safety • Human • Intern Rules • Extern : atmospheric fumes emission • Invoice Contract • Protection of the material Material • Important chains for the process EDF I 07/2017 | 18
Characterise and maintain the measurement chain 3. 1 Introduction 2 Characterise a measurement chain 3 Maintain a measurement chain 4 Example of organisation in a powerplant EDF I 07/2017 | 19
MAINTAIN A MEASUREMENT CHAIN 1) Introduction : MTR Begin of Resolution of MTR = Time between the begin and the default the default the resolution of the default. Detection Call Reparation Test Detection (Hardware or Process error) can be divided into two parts Automatic detection with alarm Human detection : a technician notices the default Call : time for the skilled worker to be on site Reparation : availability of the spare part and duration of the reparation Test : guarantee that the default is solved EDF I 07/2017 | 20
MAINTAIN A MEASUREMENT CHAIN 1) Introduction : Requirement to maintain the chain Skilled workers Spare parts Human Organisation EDF I 07/2017 | 21
MAINTAIN A MEASUREMENT CHAIN 2) Process : Definitions Verification Difference between a reference (calibrator) and the value given by the sensor. ~ 48 (1) GW Sensor read calibrator 50,5 bar indicates 50 bar If an error of 1 bar is accepted on the sensor, the sensor is OK . EDF I 07/2017 | 22
MAINTAIN A MEASUREMENT CHAIN 2) Process : Definitions Calibration Take back the sensor in this original technical specifications. Sensor Calibrator read 50,5 indicates bar 52 bar The sensor error accepted ± 1 bar After calibration Sensor calibrator read 50 indicates bar 50 bar EDF I 07/2017 | 23
MAINTAIN A MEASUREMENT CHAIN Question : is it necessary to calibrate the sensor ? Value read on the sensor Acceptable error for the process Time Formation métrologie du 25 novembre 2016 | 24
CHARACTERISATION OF A MEASUREMENT CHAIN After the characterisation of the measurement chain, we can define 4 groups for strategic chains: • Material Safety • Human • Intern Rules • Extern : atmospheric fumes emission • Invoice Contract • Protection of the material Material • Important chains for the process EDF I 07/2017 | 25
MAINTAIN A MEASUREMENT CHAIN Define the check Frequency Strategic (example) Sensor ? Yes No ~ 48 (1) GW Contract Safety No or rules? (SIL) ? Yes Yes Follow contract Periodical test to No check or rules maintain the SIL See annex 1 See annex 2 EDF I 07/2017 | 26
MAINTAIN A MEASUREMENT CHAIN Define the check Frequency (example) ~ 48 (1) GW Important More Safety No for No than one No (SIL) ? process sensor ? Yes Yes Periodicity = f(sensor, Periodicity = No test process) f(sensor, process) EDF I 07/2017 | 27
MAINTAIN A MEASUREMENT CHAIN Example : Regulatory measurement chain Example : monitoring of atmospheric fumes emissions ~ 48 (1) GW Solution STOP Perimeter : - Gas analyser in the chimney (SO2, NO, CO, O2, CO2) We are not allowed to run. - Dust analyser Control every month : - Calibration of the sensor with a reference gas. - Control and send the sensor’s drift to the authorities - Preventive check (sensor’s temperature and seal) - Change if necessary the filters EDF I 07/2017 | 28
Recommend
More recommend
