Notas del presentador Introducción de herramientas y técnicas para probar y solucionar problemas? 4 a 20 mA bucles Esta presentación es modular. Este primer.

Notas del presentador Introducción de herramientas y técnicas para probar y solucionar problemas? 4 a 20 mA bucles Esta presentación es modular. Este primer módulo es el módulo principal y se combina con cualquier otro módulo o módulos en función de la longitud deseada y el interés de los clientes Separe la clase en (4) equipos, en forma de U funciona mejor. How to use this document. This course is designed as a modular resource from which you can custom build a presentation that suits your audience. The modularity of this presentation helps you: Make it more technical by including the advanced sections. Select the topics based on the amount of time you have available Focus on issues of interest to your audience. The course is divided into five modules: 4-20mA Control Loops Digital Process Control Temperature Measurements Troubleshooting Pressure Measurements Troubleshooting Instrument Maintenance in Explosive Environments Each section contains: Information on how to troubleshoot and perform maintenance on process control systems War stories that you can use as anecdotes to demonstrate the value of knowing this content. Case studies on troubleshooting and performing maintenances on process control systems based on the low cost/no cost methodology. Save this file as a new document and arrange the items that suit your audience and time constraints to create your own custom course! Text in italics are intended for the presenter Text in normal face is suggested language for you to use with students. Tips for presenting This presentation will get you half way to making a fantastic course. The other half is you, the presenter. Here are some tips to preparing for a class: Practice Going through the entire course out loud will markedly improve your presentation. You will be able to better think ahead to the next section and be able to better engage your audience. People that look good presenting make it look easy by preparing in advance. Engage Throughout the course you will find opportunities for discussion and engagement. Use these and welcome other interactions from the class. Often, you will find that the knowledge of the people within the room can move the course along. Learn Although you are playing the role of instructor, each time you teach is an opportunity to learn how you can improve. Look for feedback from your audience. Note what worked and what did not so that you can make an even better presentation next time. Check for understanding as you present the course. Many adult learners are very hesitant to ask they the questions they need to best understand new material. You will increase the effectiveness of your presentation and build rapport with the group you are presenting to if you frequently check for understanding as you move through your presentation. There are several easy ways to check for understanding: Ask open-ended questions. By doing this, you invite learners to move beyond recall to the synthesis of the new information you are presenting. Ask learners to problem-solve, using the new information. Present a scenario where they must apply the new information to come up with a problem solution. Ask learners to prioritize. Ask questions like, “Of the available methods for troubleshooting 4-20mA control loops, which is best if you are on a tight budget? Which is best if you are on a tight time schedule?” Questions like this go beyond simple recall to encourage learners to synthesize new information. You don’t have to know it all, but you should be able to find the answer to any question you get during your presentation and follow up with the person who asked the question. Follow up allows you to be a trusted advisor and can open the door to additional sales. Get familiar with the material available on

Prueba de bucles de control de 4-20 mA
Herramientas y prácticas para la Optimización del proceso de calibración, mantenimiento y resolución de problemas Prueba de bucles de control de 4-20 mA

Módulos del Workshop Prueba de bucles de control de 4-20 mA
Probar y calibrar los instrumentos de temperatura del proceso Probar y calibrar los instrumentos de presión de proceso Introducción al control de procesos digitales Normas fundamentales y los costos asociados con los entornos de trabajo de seguridad intrínseca. After completing this course, you will be able to troubleshoot 4-20mA control loops, which you’ll learn in this module. You’ll also be able to troubleshoot digital process control. You’ll learn how to troubleshoot and calibrate process temperature instruments. You’ll also be able to troubleshoot and calibrate process pressure instruments. And you’ll also be able to identify key regulations and costs associated in explosive, or non-intrinsically safe, environments.

Diagnostico de lazos de control de 4-20 mA
Revisar el funcionamiento de un circuito de control 4- 20mA Discutir de que formas un bucle de control 4-20mA puede funcionar mal Identificar los métodos y herramientas para solucionar problemas en lazos de control 4- 20mA In this module you’ll learn about what a 4-20mA control loop is and how it operates. You’ll learn about some of the ways a 4-20 mA control loop can malfunction. And you’ll learn how to find problems and troubleshoot 4-20mA control loops.

Lazo de control 4-20 mA Medir variables de proceso o PV temperatura
sensor temperatura presión flujo frecuencia PH Medir variables de proceso o PV temperatura presión flujo Otros procesos Comunicar 4 a 20 mA al sistema de control información PV salida de control Comandar elementos de control Pueden ser digital ZERO SPAN Señal 4 to 20 mA  2200 ºC Shunt de 250 ohm  24 V + –  4 to 20 mA Lectura / Controlador DCS / PLC / Grabador Transmisor de 2 hilos Control loops in industrial process control settings measure something: pressure, temperature, flow, pH, or other process variables. Measured process variables are communicated to other equipment in the loop, such as displays and controllers. Controllers use the signal to control process output as required, such as opening or closing a flow control valve. Control loops can be analog or digital. References , slide 4 Audience Interaction Prompt: Ask participants about their experience with process control systems.

Lazo de control 4-20 mA Alimentado por la fuente de 24 V
El transmisor regula la señal de 4-20 mA proporcional a la PV Indicador interpreta la señal de 4-20 mA como PV Los Indicadores o controladores tienen una resistencia de entrada típicamente 250 ohms Crea señal de entrada 1- 5V La ley de Ohm, V = I x R 4-20 mA X = 250 ohmios 1-5V sensor temperatura presión flujo frecuencia PH ZERO SPAN Señal 4 to 20 mA  2200 ºC Shunt de 250 ohm  24 V + –  4 to 20 mA Lectura / Controlador DCS / PLC / Grabador Transmisor de 2 hilos The control loop is typically powered by a 24V loop power supply. The transmitter draws its power from the 24V loop power supply and regulates the 4 to 20 mA signal proportional to the PV or measured variable on the input such as temperature, pressure, flow, frequency or pH. The local indicator or controller interprets the 4-20 mA signal and has outputs that can be used to control or change the measured process variable. Many if not most controller inputs have a 250 ohm input shunt. A 250 ohm shunt with a 4 to 20 mA signal develops a 1-5V drop. Based on Ohm’s law, a 4-20mA current through 250 ohms of resistance will develop a 1-5 volt drop, because voltage equals current times resistance. References , slide 4 Audience Interaction Prompt: Ask participants to give examples of indicators and controllers they have seen.

Transmisores de temperatura en un lazo de control
Mide la temperatura del proceso Convierte la temperatura detectada por el sensor termopar o RTD en una señal de 4 a 20 mA Indicador / controlador interpreta la señal como la temperatura medida La salida del controlador controla el elemento de control final de proceso When temperature transmitters are in a process loop, the measured PV or primary/process variable is the temperature of the process medium, such as fluid. Typically, either a thermocouple or RTD sensor senses the temperature and converts the measurement to a 4 to 20 mA signal. The 4 to 20 mA signal is interpreted by the controller as a measured temperature, based upon the current in the loop. From there, the controller output is commonly used to control additional equipment in the process, such as flow control valves. References , slide 6-8 Audience Interaction Prompt: Ask participants to describe their experience working with process temperature measurement. Temperature input Current output Percent of span 0 °C 4 mA 0 % 75 °C 8 mA 25 % 150 °C 12 mA 50 % 225 °C 16 mA 75 % 300 °C 20 mA 100 %

Transmisores de presión en un lazo de control
Mide la presión del proceso Convierte la presión medida por el sensor a una señal de mA El indicador / controlador interpreta la señal como la presión La salida del regulador controla la válvula de seguridad para garantizar no se desarrollen presiones peligrosas Pressure input Current output Percent of span 0 psi 4 mA 0 % 25 psi 8 mA 25 % 50 psi 12 mA 50 % 75 psi 16 mA 75 % 100 psi 20 mA 100 % When pressure transmitters are in a process loop, the measured PV or primary/process variable is the pressure of the process medium, such as fluid. The pressure sensor senses the pressure and converts the measurement to a 4 to 20 mA signal. The 4 to 20 mA signal is interpreted by the controller as a measured pressure, based upon the current in the loop. From there, the controller output is commonly used to control additional equipment in the process, such as pressure relief valves or other final control elements. References , slide 9 Audience Interaction Prompt: Ask participants to give examples of control systems that use pressure.

Problemas más comunes en los lazos de control
Problemas de cableado y terminación Fuentes de alimentación Sistema de E/S Transmisores Sensores transmisor de temperatura Temperature input Current output Percent of span 0 °C 4 mA 0 % 75 °C 8 mA 25 % 150 °C 12 mA 50 % 225 °C 16 mA 75 % 300 °C 20 mA 100 % You can have wiring problems such as bad terminations, compromised insulation, corrosion, or contamination. You can have problems with the 24V loop power supply. Noisy, defective or overloaded power supplies can cause erratic mA loop operation or failures. Or you can have bad I/O into the controller. If the mA signal is correct and the controller does not interpret the mA signal correctly, then control of the process is lost. A common failure in aging systems is a bad transmitter. If the transmitter does not change the mA signal correctly to respond to the measured pressure or temperature the control system will not correct to adjust the PV correctly. One other element of failure is a bad temperature sensor or clogged pressure capillary. In the case of a temperature transmitter, if the temperature sensor is defective or marginal, the transmitter either cannot sense the temperature or will not measure it accurately.. In the case of a pressure transmitter, if the connection to the process is clogged the transmitter cannot accurately measure the pressure. References , slide 10-11 Audience Interaction Prompt: Ask participants what problem they most commonly encounter. transmisor de presión Pressure input Current output Percent of span 0 psi 4 mA 0 % 25 psi 8 mA 25 % 50 psi 12 mA 50 % 75 psi 16 mA 75 % 100 psi 20 mA 100 %

Herramientas para la solución de problemas en lazos de mA
Qué se puede medir o generar Herramienta de medición y generación Que información brinda Medir señales 4 a 20 mA DMM. Calibrador de lazo , pinza de mA, ProcessMeter Si el valor de mA medido es el valor esperado Fuente 4 mA a 20 mA Calibrador de lazo , pinza de mA, ProcessMeter Si el dispositivo de entrada de mA funciona correctamente Simular señales de mA 4 mA a 20 Calibrador de lazo , FLUKE-772 o FLUKE-773, ProcessMeter Si la fuente de alimentación y el cableado de E / S y funciona correctamente, realice la prueba de sustitución transmisor Mide 24 V tensión de bucle DMM, Calibrador de lazo , FLUKE-773, ProcessMeter Si el suministro de 24V esta disponible, si es defectuoso o se cae cargado Suministro de 24 V de tensión de bucle Calibrador de lazo , FLUKE-772 o FLUKE-773, FLUKE-789 Si una prueba de sustitución de alimentación instalada resuelve el problema Fuente 0V a 10V, 1V a 5V Calibrador de lazo con fuente de tensión (715) o Pinza de mA (773) Si el dispositivo de entrada de tensión de E/S o de otro tipo está funcionando correctamente mediciones de continuidad DMM, ProcessMeter, algunos multifunción Encontrar circuitos abiertos, malas terminaciones, conexiones resistivas y problemas de cables You can measure the 4 to 20 mA signal with a digital multimeter, loop calibrator, mA clamp or ProcessMeter and the technician can compare the expected mA value in the loop to the actual value measured. You can source a 4 to 20 mA signal with a loop calibrator, enabled mA clamp or ProcessMeter and the technician can observe the response from a mA input device or control system I/O to determine if it responds correctly. You can simulate a 4 to 20 mA signal with a loop calibrator, enabled mA clamp or ProcessMeter and the technician can determine if the power supply, wiring and I/O are all working correctly. You can also use this function to do a transmitter substitution test. You can measure loop voltage with a DMM, loop calibrator, mA clamp or ProcessMeter and the technician can compare the expected measurement of 24V to the actual value measured. If the voltage is too low or noisy it might be defective or overloaded. You can use the 24V loop power supply from a loop calibrator, enabled mA clamp or ProcessMeter. If a substitution test for the loop power supply solves the problem the technician knows that the installed power supply is defective or overloaded. You can source 0 to 10V or 1 to 5V with specialized loop calibrator with a voltage source such as the Fluke-715 or an enabled mA clamp such as the Fluke-773 into a voltage input device or Voltage I/O. This test tells the technician if the device or I/O are working correctly. Continuity measurements can be made with a DMM, ProcessMeter or some multifunction calibrators. The technician can test for open circuits, mis-wires, bad terminations and resistive connections. References , slide 12 Audience Interaction Prompt: Ask participants about other tools they find useful in measuring control loops.

Verificar la señal de 4 a 20 mA
Medir la señal 4 a 20 mA en serie o utilizar una pinza amperométrica mA Verificar fuente de alimentación Los problemas de cableado Problemas de E / S terminaciones fallidas In series, “Break the loop” Solución de problemas: Medir el valor mA en el bucle. Si se mide 0 mA, continuar diagnosticando. There can be a number of reasons why a 4-20mA control loop would have no signal. One of these is that the power supply is bad. Wiring problems, such as broken wiring, can also cause no signal. Another possible cause of no signal is an I/O problem. Bad connections can cause also cause no signal. References , slide 10-11 Audience Interaction Prompt: Ask participants to give examples of problems they’ve encountered that resulted in no signal on a control loop.

Solución de problemas del lazo de 4 a 20 mA
Prueba de sustitución del transmisor Solución de problemas: Desconecte el transmisor y conectarlo al calibrador de lazo o ProcessMeter en su lugar. Ajuste la función de simular mA y ajuste a un valor de 4 a 20 mA. Verifique por valor correcto en el indicador. Prueba los cables, fuente de alimentación y de E / S en un solo paso If you suspect a wiring problem, you can perform a transmitter substitution test. You can also measure DC voltage on the loop to verify that the voltage drop on the transmitter input is correct. You should also use a digital multimeter to measure continuity. References , slide 17-18 Milliamp loop troubleshooting.ppt, slices 5-6 Audience Interaction Prompt: Ask participants about their experience with transmitter substitution tests.

Solucionar problemas de suministro de energía
Mida la tensión de alimentación lazo Utilice Calibrador de lazo. ProcessMeter o multímetro Solución de problemas: Medir la fuente de alimentación. Debe ser de aproximadamente 24. Si la medición es sospechosa, realizar la prueba de sustitución. One of the first steps in testing is to make a power supply check. If the power supply measures a full 24V it is likely working correctly. If the supply is loaded down or noisy it can be the source of problems with the control loop. If the 24V loop power supply is suspected to be defective you can perform a substitution test to supply 24V power to the loop. To do this, you can use the 24V loop supply from either a loop calibrator for the 789 ProcessMeter. Remove the power supply connection and connect the voltage supply from the test tool in its place. If using this external test supply in a substitution test solves the problem, the power supply or power supply overloading is the likely culprit. References , slide 17-18 Audience Interaction Prompt: Ask participants what their process is for troubleshooting power supply problems.

Mida la tensión de alimentación lazo Utilice Calibrador de lazo. ProcessMeter o multímetro Solución de problemas: Desconecte el suministro de energía lazo instalado. Conecte la fuente de alimentación de lazo de 24 V del calibrador de lazo o ProcessMeter es su lugar ". Si el problema se resuelve la fuente de alimentación es defectuoso o sobrecargado One of the first steps in testing is to make a power supply check. If the power supply measures a full 24V it is likely working correctly. If the supply is loaded down or noisy it can be the source of problems with the control loop. If the 24V loop power supply is suspected to be defective you can perform a substitution test to supply 24V power to the loop. To do this, you can use the 24V loop supply from either a loop calibrator for the 789 ProcessMeter. Remove the power supply connection and connect the voltage supply from the test tool in its place. If using this external test supply in a substitution test solves the problem, the power supply or power supply overloading is the likely culprit. References , slide 17-18 Audience Interaction Prompt: Ask participants what their process is for troubleshooting power supply problems.

Solución de problemas de E / S
Solución de problemas del controlador de E / S Solución de problemas: Fuente de la señal mA directamente en el I / O del controlador, compruebe que funciona correctamente. Compruebe la indicación correcta en el controlador. Transmitter substitution tests are also appropriate for troubleshooting I/O problems. You can also test I/O problems by sourcing a signal, which involve using a loop calibrator to generate a 4-20mA signal on the loop, then verifying the value on the controller display. You can also simulate a signal on the loop. Verify the value on the display against the value you’re simulating. References , slide 17-18 Milliamp loop troubleshooting.ppt, slices 5-6 Audience Interaction Prompt: Ask participants when they prefer to source a signal vs. simulate a signal.

Solución de problemas del controlador de E / S Solución de problemas: Si no hay indicación en el controlador, la entrada de E / S puede tener un fusible abierto. Verifique por medición a través de la entrada de? 250 ohms. Transmitter substitution tests are also appropriate for troubleshooting I/O problems. You can also test I/O problems by sourcing a signal, which involve using a loop calibrator to generate a 4-20mA signal on the loop, then verifying the value on the controller display. You can also simulate a signal on the loop. Verify the value on the display against the value you’re simulating. References , slide 17-18 Milliamp loop troubleshooting.ppt, slices 5-6 Audience Interaction Prompt: Ask participants when they prefer to source a signal vs. simulate a signal.

Problemas de cableado, medidas de continuidad
Solución de problemas: Aislar la fuente de alimentación Hacer un punto a medidas de continuidad en busca de conexiones abiertas. Verifique 250 ohms en entrada del controlador Transmitter substitution tests can be used to help identify connection problems. You can also measure DC voltage on the loop to verify that the voltage drop on the transmitter input is correct. You should also use either a digital multimeter or ProcessMeter to measure continuity. References , slide 17-18 Milliamp loop troubleshooting.ppt, slices 5-6 Audience Interaction Prompt: Ask participants if they have encountered control loops with connection problems.

Los síntomas de errores en señales de control
? El transmisor no cambia la señal mA correctamente Señal de miliamperios no refleja con exactitud la temperatura o la presión medida Incapacidad para conducir la señal mA a plena escala (20 mA) ? We’ll cover transmitter troubleshooting more in depth in temperature and pressure sections, but a common suspected failure in aging systems is a bad transmitter. If the transmitter does not change the mA signal correctly to respond to the measured temperature the control system will not correct to adjust the temperature or primary process variable correctly. Often it is not the transmitter rather a bad temperature sensor. If the thermocouple or RTD temperature sensor is defective the transmitter cannot sense the temperature. In pressure transmitters, when the transmitter is suspect, the real problem might be a clogged input capillary. If the connection to the process is clogged the transmitter cannot accurately measure the pressure. References , slide 21 Audience Interaction Prompt: Ask participants which measurements they find most useful in troubleshooting transmitters.

Causas de los errores en las señales de control
Transmisor defectuoso o mal ajustado Sensor de presión o de temperatura defectuoso Entrada obstruida para transmisor de presión Cableado resistiva o conexiones de cableado Mal el aislamiento del cableado Fuentes de alimentación sobrecargadas o defectuosas A bad signal in a control loop can have a number of causes, including a defective transmitter. Resistive wiring or connections can also cause a bad signal. Bad insulation is another common trouble source that can result in a bad signal in the loop. One of the common symptoms of a resistive connection is that the transmitter cannot drive to full scale, or 20mA. Symptom of resistant connections, the transmitter cannot drive to full scale (20 mA). References , slide 10-11 Audience Interaction Prompt: Ask participants to give examples of causes of a bad signal.

Prueba de los problemas de cableado para señales de mA defectuosas
Prueba de sustitución del transmisor como se ha descrito antes Solución de problemas: Compare cuidadosamente valor del indicador de valor de miliamperios esperado. Si un transmisor inteligente HART realizar una prueba de lazo Si el valor indicado está fuera del valor esperado realizar ajuste de miliamperios digital si un transmisor inteligente HART If you suspect a wiring problem, you can perform a transmitter substitution test. References , slide 17-18 Milliamp loop troubleshooting.ppt, slices 5-6 Audience Interaction Prompt: Ask participants how the determine if a problem is a wiring problem.

Prueba de lazo HART Solución de problemas:
Temperature transmitter Instrument Output 4 to 20 mA output to PLC or DCS PVAO command (from communicator or Fluke 754) Loop test output trim Smart transmitter output Solución de problemas: Utilice la prueba de bucle para comandar el transmisor inteligente HART y generar una señal de mA Fuentes del transmisor una señal de mA en el I / O Verificar la exactitud de la indicación en la pantalla Transmisor de pruebas? Salida, fuente de alimentación, el cableado de E / S In the case of circuits that have HART smart transmitters installed you can perform what’s called a loop test. By sending a digital signal to the transmitter, you command it to output a milliamp value. In this example, the 754 commands the transmitter to output the mA signal and measures the value simultaneously for inter-comparison purposes. These values can be also be compared to the expected value on the indicator. If all values agree the control loop is working properly. In the event they do not agree further troubleshooting of the loop is warranted. This tests the mA output of the transmitter, the wiring and control system I/O. If loop operation is incorrect after this test passes the problem is likely on the sensor side of the transmitter.

Ajuste de salida analógica de un transmisor HART
"Fetch" recupera el valor actual que se está midiendo "Enviar" transmite la corrección de instrumento y realiza el ajuste Ajuste ambos 4 mA y 20 mA Solución de problemas: The 753 does not have this ability. Una vez completado el ajuste, comparar cuidadosamente el valor indicado con una señal de mA. Utilice la función de prueba de bucle para cambiar el valor impulsado por el transmisor en el sistema de control de E / S

Causas de una señal ruidosa
Mal aislamiento Blindaje del cable defectuoso Fallos de tierra Fuentes de alimentación marginales Errores de colocación de los cables (proximidad a fuentes de ruido) Several factors can create a noisy signal in a 4-20mA control loop. One common problem is a ground loop. Bad insulation on signal wires can also create noise. And inattention to cable runs and cable trays can result in noise in the signal, as well. References , slide 17-18 Milliamp loop troubleshooting.ppt, slices 5-6 Audience Interaction Prompt: Ask participants which tools they find most useful in troubleshooting a noisy signal.

Solución de problemas de ruido en la señal
Medir el ruido Verlo con Osciloscopio Solución de problemas Mida el voltaje de CA con un DMM Verlo con un Osciloscopio Sólo debe haber unos pocos mili voltios ACV To troubleshoot suspected cable routing problems, you’ll need to take noise measurements. You can measure the AC voltage with a digital multimeter. Also, you can use an oscilloscope to get a better picture of noise on the line. References , slide 4 , p, 8. Audience Interaction Prompt: Ask participants when they find an oscilloscope useful.

Prueba de aislamiento Prueba de fugas Solución de problemas:
Desconecte los cables en ambos extremos para asegurar que no se tocan o con tierra Prueba uno contra el otro y el blindaje del cable Resistencia cuantificable indica cableado de problemas de fugas Problems with insulation can cause energy leakage and incorrect resistance. To identify insulation problems, disconnect the wires and use an insulation resistance tester. Use the insulation resistance tester to test the wires against each other and against the cable shield in order to help find deteriorated insulation on signal wires. References , slide 4 , p, 8. Audience Interaction Prompt: Ask participants to describe their process for troubleshooting insulation problems.

Solución de problemas de lazos de tierra
Se forma un bucle de tierra cuando dos terminales conectados en un circuito se encuentran en diferentes potenciales de tierra. Hace que la corriente fluya en la interconexión, y puede producir ruido. Medición de la resistencia del blindaje a tierra. La resistencia debe aumentar a medida que uno se aleja de la conexión a tierra prevista. Solución de problemas: A ground loop forms when two connected terminals in a circuit are at different ground potentials. This difference causes a current to flow in the interconnection, which can produce noise. You can identify ground loops by testing continuity with a digital multimeter. Look for incorrect resistance measuring from the shield to ground. Resistance should increase as you move away from the intended ground connection. If not the shield is grounded at more than one location. References , slide 17-18 Milliamp loop troubleshooting.ppt, slices 5-6 Audience Interaction Prompt: Ask participants to give examples of ground loop problems they have encountered.

Hands on. PLC Indicador alimentado por el lazo muestra el% del span
Transmisor de temperatura HART transmisor de presión analógico 0 a 100 PSI Interruptor de presión 0 a 10 PSI Fuente de alimentación 24 Vdc Alimentacion220V bloque de conexión

Cableado 250 ohm PT 100 13 12 – + VALVE 100 + – 11 – + + – 14 7 15
24 V Loop Supply – 11 Loop Power Fuse – + + – 14 7 15 PLC 100 10 6 3 y 4, los contactos normalmente cerrado TT 100 – 9 8 + 4 y 5, contactos normalmente abierto

Verificar la señal de 4 a 20 mA
Medir la señal 4 a 20 mA en serie o utilizar una pinza amperométrica mA Verificar fuente de alimentación Los problemas de cableado Problemas de E / S terminaciones fallidas In series, “Break the loop” Solución de problemas: Medir el valor mA en el bucle. Si se mide 0 mA, continuar diagnosticando. There can be a number of reasons why a 4-20mA control loop would have no signal. One of these is that the power supply is bad. Wiring problems, such as broken wiring, can also cause no signal. Another possible cause of no signal is an I/O problem. Bad connections can cause also cause no signal. References , slide 10-11 Audience Interaction Prompt: Ask participants to give examples of problems they’ve encountered that resulted in no signal on a control loop.

789 prueba de medición de lazo mA
Mida la señal mA con el 789 Levante el fusible. Desconecte el cable de conexión del bloque de terminal # 6, Conecte medida del cable de prueba mA + (rojo) al cable conectado a # 10 Conecte - (negro) del cable de prueba mA al bloque de conexión terminal # 6 Vuelva a conectar el fusible Comparar el valor medido y mA% al indicador de mA% del span Deja instalación conectada para la próxima prueba.

789 y 700G prueba del transmisor
Conecte la bomba manual y manómetro con conexión T, como se muestra. Cierre la válvula de purga suavemente (en el círculo rojo) Cambie la presión de entrada con la bomba de mano y note la relación entre la presión aplicada y el valor mA, % del rango de la pantalla 789 Aplicar los valores de entrada de la tabla y comprobar la lectura de mA y el valor % en el indicador Pressure input Current output Percent of span 0 psi 4 mA 0 % 25 psi 8 mA 25 % 50 psi 12 mA 50 % 75 psi 16 mA 75 % 100 psi 20 mA 100 %

773 prueba de lazo Mida la señal mA sin interrumpir el circuito Encienda el 773, presione cero y luego conéctese a los cables del indicador de intervalo Tenga en cuenta, al 773 hay que ajustarle el cero antes de conectarlo Compare el % del rango del 773 al indicador, deben de estar cerca. Cambie la presión y vea el cambio del valor de corriente, Desconecte el 789 para la próxima prueba Reconecte el cable de # 10 y # 6 1

Solución de problemas del controlador de E / S Solución de problemas: Fuente de la señal mA directamente en el I / O del controlador, compruebe que funciona correctamente. Compruebe la indicación correcta en el controlador. Transmitter substitution tests are also appropriate for troubleshooting I/O problems. You can also test I/O problems by sourcing a signal, which involve using a loop calibrator to generate a 4-20mA signal on the loop, then verifying the value on the controller display. You can also simulate a signal on the loop. Verify the value on the display against the value you’re simulating. References , slide 17-18 Milliamp loop troubleshooting.ppt, slices 5-6 Audience Interaction Prompt: Ask participants when they prefer to source a signal vs. simulate a signal.

Prueba de fuente de mA, verificar el indicador
Levante el fusible Desconecte los cables 11 y 13 Cable negro al 15, Rojo al 14 función de fuente de mA Flechas arriba / abajo para cambiar el valor de mA Comparar con el indicador de % Gire a la posición de rampa El botón azul de funciones especiales para cambiar la rampa Reconecte los cables y 15-11

Solución de problemas del lazo de 4 a 20 mA
Prueba de sustitución del transmisor Solución de problemas: Desconecte el transmisor y conectarlo al calibrador de lazo o ProcessMeter en su lugar. Ajuste la función de simular mA y ajuste a un valor de 4 a 20 mA. Verifique por valor correcto en el indicador. Prueba los cables, fuente de alimentación y de E / S en un solo paso If you suspect a wiring problem, you can perform a transmitter substitution test. You can also measure DC voltage on the loop to verify that the voltage drop on the transmitter input is correct. You should also use a digital multimeter to measure continuity. References , slide 17-18 Milliamp loop troubleshooting.ppt, slices 5-6 Audience Interaction Prompt: Ask participants about their experience with transmitter substitution tests.

789 prueba simulacion mA Levante el fusible
Desconecte las conexiones 6 y 7 Conecte el 789, Rojo al # 10 y Negro de # 12 Gire la 789 a la fuente de mA Conecte el fusible Flechas arriba / abajo para cambiar los valores mA simular Girar el 789 a la posición de rampa Presione el botón azul de función para cambiar el estilo de rampa Levante fusible de potencia en bucle, desconecte los cables de prueba. Vuelva a conectar los cables: # 10 a # 6, # 12 a # 7 1 2

Mida la tensión de alimentación lazo Utilice Calibrador de lazo. ProcessMeter o multímetro Solución de problemas: Medir la fuente de alimentación. Debe ser de aproximadamente 24. Si la medición es sospechosa, realizar la prueba de sustitución. One of the first steps in testing is to make a power supply check. If the power supply measures a full 24V it is likely working correctly. If the supply is loaded down or noisy it can be the source of problems with the control loop. If the 24V loop power supply is suspected to be defective you can perform a substitution test to supply 24V power to the loop. To do this, you can use the 24V loop supply from either a loop calibrator for the 789 ProcessMeter. Remove the power supply connection and connect the voltage supply from the test tool in its place. If using this external test supply in a substitution test solves the problem, the power supply or power supply overloading is the likely culprit. References , slide 17-18 Audience Interaction Prompt: Ask participants what their process is for troubleshooting power supply problems.

Prueba de voltaje de alimentación
Función Medida Volts DC Mide 24 Vdc + / - 0,25 V?

Mida la tensión de alimentación lazo Utilice Calibrador de lazo. ProcessMeter o multímetro Solución de problemas: Desconecte el suministro de energía lazo instalado. Conecte la fuente de alimentación de lazo de 24 V del calibrador de lazo o ProcessMeter es su lugar ". Si el problema se resuelve la fuente de alimentación es defectuoso o sobrecargado One of the first steps in testing is to make a power supply check. If the power supply measures a full 24V it is likely working correctly. If the supply is loaded down or noisy it can be the source of problems with the control loop. If the 24V loop power supply is suspected to be defective you can perform a substitution test to supply 24V power to the loop. To do this, you can use the 24V loop supply from either a loop calibrator for the 789 ProcessMeter. Remove the power supply connection and connect the voltage supply from the test tool in its place. If using this external test supply in a substitution test solves the problem, the power supply or power supply overloading is the likely culprit. References , slide 17-18 Audience Interaction Prompt: Ask participants what their process is for troubleshooting power supply problems.

Sustitución de la fuente de alimentación
Levante el fusible, desconecte los cables de las conexiones 10 y 11 y conectar como se muestra: Cambie la presión Observe mA y% Levante el fusible Desconecte los cables de prueba Vuelva a conectar los cables (azul-10, blanco 11)

Herramientas para la solución de problemas en lazos de mA
Qué se puede medir o generar Herramienta de medición y generación Que información brinda Medir señales 4 a 20 mA DMM. Calibrador de lazo , pinza de mA, ProcessMeter Si el valor de mA medido es el valor esperado Fuente 4 mA a 20 mA Calibrador de lazo , pinza de mA, ProcessMeter Si el dispositivo de entrada de mA funciona correctamente Simular señales de mA 4 mA a 20 Calibrador de lazo , FLUKE-772 o FLUKE-773, ProcessMeter Si la fuente de alimentación y el cableado de E / S y funciona correctamente, realice la prueba de sustitución transmisor Mide 24 V tensión de bucle DMM, Calibrador de lazo , FLUKE-773, ProcessMeter Si el suministro de 24V esta disponible, si es defectuoso o se cae cargado Suministro de 24 V de tensión de bucle Calibrador de lazo , FLUKE-772 o FLUKE-773, FLUKE-789 Si una prueba de sustitución de alimentación instalada resuelve el problema Fuente 0V a 10V, 1V a 5V Calibrador de lazo con fuente de tensión (715) o Pinza de mA (773) Si el dispositivo de entrada de tensión de E/S o de otro tipo está funcionando correctamente mediciones de continuidad DMM, ProcessMeter, algunos multifunción Encontrar circuitos abiertos, malas terminaciones, conexiones resistivas y problemas de cables You can measure the 4 to 20 mA signal with a digital multimeter, loop calibrator, mA clamp or ProcessMeter and the technician can compare the expected mA value in the loop to the actual value measured. You can source a 4 to 20 mA signal with a loop calibrator, enabled mA clamp or ProcessMeter and the technician can observe the response from a mA input device or control system I/O to determine if it responds correctly. You can simulate a 4 to 20 mA signal with a loop calibrator, enabled mA clamp or ProcessMeter and the technician can determine if the power supply, wiring and I/O are all working correctly. You can also use this function to do a transmitter substitution test. You can measure loop voltage with a DMM, loop calibrator, mA clamp or ProcessMeter and the technician can compare the expected measurement of 24V to the actual value measured. If the voltage is too low or noisy it might be defective or overloaded. You can use the 24V loop power supply from a loop calibrator, enabled mA clamp or ProcessMeter. If a substitution test for the loop power supply solves the problem the technician knows that the installed power supply is defective or overloaded. You can source 0 to 10V or 1 to 5V with specialized loop calibrator with a voltage source such as the Fluke-715 or an enabled mA clamp such as the Fluke-773 into a voltage input device or Voltage I/O. This test tells the technician if the device or I/O are working correctly. Continuity measurements can be made with a DMM, ProcessMeter or some multifunction calibrators. The technician can test for open circuits, mis-wires, bad terminations and resistive connections. References , slide 12 Audience Interaction Prompt: Ask participants about other tools they find useful in measuring control loops.

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Notas del presentador Introducción de herramientas y técnicas para probar y solucionar problemas? 4 a 20 mA bucles Esta presentación es modular. Este primer.

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