This episode of Ask an Expert for industrial sensors examines and provides answers to interesting sensing questions we've received from customers just like you. We explore and answer these questions:
1. Motion detection sensor RMS-M-NA. Could this sensor be used to detect people in an area of a museum?
2. Can the capacitive sensor CJ40-FP-A2-P1 survive in a vacuumized vessel?
3. What is the Teach-in cable for the ultrasonic sensor UB100-F77-E2-V31, and how is it used?
4. Can you use an incremental rotary encoder with a higher PPR to replace one with a lower PPR?
5. What is the life expectancy of an inductive sensor in an outdoor, humid environment?
Feel free to ask us your sensing questions, and we'll do our best to reply with the whys and hows of a particular solution.
John: Welcome to Ask an Expert! Hi, this is John Appleson, Marketing Manager with Pepperl+Fuchs. Today, I'm joined by Tracy Molnar. Tracy works as an Application Engineer here at Pepperl+Fuchs. So welcome, Tracy and thanks for being here!
Tracy: Hi John, thanks for asking me.
John: The first question asks about a sensor that is able to detect people in a specific area at a museum. The area of detection is 96 inches by 96 inches, and the sensor would be approximately 96 inches off the floor. The customer is wondering if an IR area scanner photoelectric sensor would work. Tracy, what solution can we offer to this customer?
Tracy: Well, the area this customer wants to monitor is pretty big, it's about 8 feet by 8 feet. For the detection of people in this area, my choice would be a motion sensor from the RMS series (RMS-M-NA). This sensor uses radar technology to cover an area larger than most infrared or ultrasonic devices.
John: Tracy, this customer wants to know if the CJ40-FP-A2-P1 capacitive sensor comes with a cable or a connector? He also wonders if this capacitive sensor is potted, and whether it could withstand installation in a vacuumized vessel. Can you shed some light on this?
Tracy: Sure! First, I'll address the part about the sensor's connection. It doesn't have a cable, it doesn't have a connector. This particular model has a terminal compartment, which means it is designed for hard-wiring. We do also have a version of this sensor, it has a different model number, that has a pre-wired M12 connector, and that version would require a mating cordset for connection. The customer's second question has to do with the sensor's physical construction. The electronics in our capacitive and inductive sensors are potted, and their housings can withstand low pressure and vacuum levels without damage to the sensor. Customers can find details by referring to the standard listed on this product's datasheet.
John: We received a call from a customer wondering how to teach the UB100-F77-E2-V31 ultrasonic sensor, if a cable is used in the process, and how he would go about it. Would you please clear this up?
Tracy: The instructions for using the external teach input on this sensor can be found on the sensor's datasheet. The input is on pin 2 of the connector, and it's used to set the switchpoint of the sensor, which is the point beyond which target objects will not activate the sensor's output. This customer may also be asking about the optional push-button programming unit that can be used between the sensor and the power supply, which can provide the same function as connecting and disconnecting the teach input wire during programming. For this particular model, the pushbutton programmer is model UB-PROG4-V31.
John: In this next application, the customer wants to know if he can use an incremental rotary encoder 10-23321_R-550 with 550 pulses per revolution, in place of the same encoder with 100 pulses per revolution, or PPR. Tracy, what can you suggest?
Tracy: The pulses per revolution, or PPR, indicates the maximum resolution of an encoder. You can use a higher resolution encoder, for example, with 550 PPR, as a replacement for a lower resolution one, such as 100 PPR, as long as there is a provision in your pulse counter for a division by, in this case 5.5, to be calculated. In this case the customer's encoder used to output 100 pulses per revolution, and if he replaces it with the 550 PPR model, he'll have to divide the count, in order to have it mean the same rotational movement that it did with the lower resolution encoder.
John: In this final question, a customer has an outdoor, humid environment, and wants to use an inductive sensor 3RG4021-0AG33-PF. He would like to know the life expectancy of the sensor when used under such conditions. He also wants to know if the target material needs to be within a certain range around the diameter of the sensor, in order to be detected. Tracy, can you please shed some light on these questions?
Tracy: First I'll answer the life expectancy question. The sensor this customer is asking about is an inductive sensor with a waterproof IP rating and a wide operating temperature range of -40 °C to +85 °C. The sensor electronics have no moving parts, and should last decades or more, as long as the sensor is operated according to the specifications listed on its datasheet. The attached cable and wiring for the sensor should be protected from the weather using an appropriate conduit. The customer's second question has to do with where the target needs to be in order to be detected by the sensor. The sensing field is generated from the sensor's face, and any target metal that enters this field when moving toward the sensor axially, or across the sensing face laterally, will be detected at a certain point based on the properties of the target. These properties include size, shape, and material. The best way to visualize this is using a response curve that we have for inductive sensors in the introduction section of our catalog. This is a document that I often send to customers who are asking this question.
John: Well, that concludes this segment of Ask an Expert. I'd like to thank Tracy for joining me today, and thank our audience as well.