Question

A request has been received from an external customer for recommendations for linear position control sensors to be used in an explosive environment. For this reason unsafe electrical contacts must be avoided. The sensors will be installed in locations that are hazardous to access except when the plant is shut down annually for maintenance. The span required is 5cm. The sensor case must not permit any ingress of dust or of water.

State what type of position sensors you would recommend and give your reasons. Sketch both the recommended sensor and circuit, and explain its operation. Comment on how signal conditioning requirements can now be met. Identify the durability required in respect of dust and water ingress.

Answer 1

A linear position control sensor is a special type of sensor that reads the linear position of a particular device to which it is attached. Normally these type of sensors work in the following way:

The current or present position information is converted into an encoded analog or digital signal by the sensor. In the next step, this encoded analog or digital signal is decoded by the motion controller into meaningful position information. In this type of sensors, position information is analyzed by the sensor at regular intervals. Motion is determined by change in information over time.

The current problem asks for a linear position control sensor in an explosive environment. Also it asks for a sensor that will be durable even in the case of water and dust ingress. Keeping all these paraeters in mind, the right thing will be Balluf Micropulse TA12 hazardous area linear position control sensor.

Let's explain the reasons for choosing this particular sensor:

1. It offer's non contact operation which is very reliable in the explosive operation.

2. The product is very rugged i.e. it is durable even in the presence of dust and water.

3. Sensor is also corrosion resistant which is very important.

4. The sensor can work on a wide range of operating temparature ranging from as low as -40 degree C to as high as 80 degree C.

5. The electronic components present in the sensors are made in such a way so that in case of any problem they can be replaced very easily. This ensures ease for the customers.

Operation of these type of sensors is explained before. Same thing will be applicable here.

Since the product is a patended one, the circuit is not available. It is the property of the Balluf Corporation.

Hope the description will help you.