A potentiometer is defined as a 3 terminal resistor having a rotating or sliding contact that makes up the adjustable voltage divider. If you are using only the two terminals present in it (one end and the wiper), then it behaves like a variable resistor or rheostat.

Potentiometer, a measuring instrument, is a voltage divider which is used to measure the electric potential difference. This electric component has got its name as a potentiometer because it is an implementation of the same principle.

Potentiometers are used mainly in controlling electrical devices like in audio equipment for controlling the volume. Potentiometers that are controlled by a mechanism can be utilized as position transducers, like, as used in a joystick. Potentiometers are used very often to control significant power (greater than watt) directly since the dissipated power in the potentiometer is comparable to the power present in the controlled load.

Nomenclature for Potentiometers

There is a vast amount of electronic equipment present in the industry. For the simplification of the people, each of them comes with its code and nomenclature. Let's have a look at the nomenclature as described for a potentiometer.

• Trimmer pot or Trimpot – A trimmer potentiometer is a potentiometer that is generally meant to be calibrated once or infrequently for the electrical signal to get tuned finely.
• Thumbwheel pot or Thumb pot – A rotating potentiometer (small) which can be calibrated infrequently with the help of small thumbwheel.
• Slider pot or Slide Pot – This kind of potentiometer is adjusted with the help of a wiper by shifting it right or left (or even up and down - It depends on the way of its installation), generally with the help of thumb or a finger.

Digital Potentiometer

A digital potentiometer, generally known as digipot, is an electronic equipment that copies all the functionality of analog potentiometers. Just like the analog potentiometer, the resistance present between the 2 terminals can be adjusted through digital input signals.

There are 2 main functional types of digital potentiometers.

• Non-Volatile – It uses a strong mechanism like that present in EEPROM or flash memory to retain their set position.
• Volatile – It loses its set position as soon as the power is removed from them. It is generally designed to initialize at the base position.

The use of digipot is much complex than that of a simple analog potentiometer. Not only that, but there are many noticeable limitations as well. Still, they are broadly utilized, regularly for factory calibration and adjustment of hardware, particularly where the constraints of mechanical potentiometers are dangerous.

Membrane Potentiometers

A membrane potentiometer is a potentiometer that takes the help of a conductive membrane that is distorted by a sliding element to contact a resistor voltage divider. Linearity lies between 0.5 percent to 5 percent as per the designs, materials, and processes used while manufacturing. The repeat accuracy generally lies in the range of 0.1mm to 1.0mm with an infinite resolution theoretically.

This was all we have regarding Potentiometers. Brands that manufacture them are Bourns, Honeywell, and Vishay. Make sure to go through them using the links as provided.

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The act of sensing the absence or the presence of a substance (object) with a non-contact or contact sensing device is known as presence sensing. The sensors generate an output signal (electrical) that can be utilized to control processes or equipment.

Limit switches are a category of sensing device that helps in detecting the presence and absence of objects. Mechanical limit switches refer to those switches that can be activated mechanically i.e. they consist of some kind of lever, arm, plunger, knob, etc. which is mechanically or physically activated. Other kinds of switches/sensors include light sensors, proximity sensors, etc.

As said earlier, these limit switches help in the sensing of objects in industrial applications. The device is named as 'limit switch' due to the operation it performs. As the target (object) comes in close contact with the switch’s operator, it moves the actuator to the limit where the electrical contacts change state. Because of this mechanical activity, the electrical contacts are either closed (in an open circuit) or opened (in a closed circuit). Capacitive proximity, photoelectric sensors, and inductive proximity carry out this same procedure through non-contact detection.

Let's have a look at some of the basic functions linked with limit switches.

• Counting
• Detecting Speed
• Detecting Absence or Presence
• Detecting Travel limit and Positioning
• Detecting Range of Movement
• When an unsafe condition forms up it breaks the live circuit.

Limit switches have found its use in many commercial and industrial applications which requires safety. Let’s check out some of its strengths as well as its weaknesses.

Strengths

• Limit switches can withstand several environments.
• It provides high accuracy, repeatability, and precision.
• It’s quite a good economic sensing solution.
• It’s not a big deal to switch high currents (approx. 10A).

Weaknesses

• The mechanical component used in it may wear out.
• It needs to make physical contact with an object to actuate.

Advantages of using Limit Switches

• It can operate multiple loads.
• It consumes less electrical energy.
• It can be utilized in nearly any industrial habitat.
• Loads can be switched with high inductance.
• It’s very much specific regarding repeatability and accuracy.

Disadvantages of Limit Switches

• These switches are by and large confined to hardware working at moderately low speeds.

Basic Limit Switch Design and Terminology

• Pretravel – It is the angle or the distance that the actuator must go through to trip the contacts.
• Operating Point – It is the position of the actuator where the contact break to the position of operation.
• Release point – It is the position of the actuator at which the contacts come back to their initial state.
• Differential – It is the length between contacts reset and contacts trip.
• Overtravel – It is the movement of the actuator past the contacts trip point.
• Initial Position – It is the position of the actuator when no external force is applied to it.
• Operating Force (Torque) – It is the amount of force needed to move the actuating element.

This was all we have regarding limit switches. Brands that manufacture them are Omron, Honeywell, and QUADRANT. Make sure to follow them using the links as provided.

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Light curtains come under optoelectronic devices that are utilized to defend personnel in the proximity of moving machinery that can cause harm like winders, palletizers, and winders. Light curtains can be utilized as an alternative to traditional machine guarding and other mechanical barriers. By decreasing the requirement for physical barriers and guards, these safety light curtains can uplift the practicality of the hardware they are guarding. It should also be noted that by the use of light curtains the efficiency and the operability of the machinery can be improved. 

Description

Light curtains can be categorized under those gadgets that are known as Presence Detection devices. Other popular Presence Detection devices include laser scanners and pressure-sensitive safety mats. Most significant uses of safety relays are in industries that work upon robotic cell setup.

Light curtains come with a transmitter and a receiver. The transmitter makes a projection of several parallel light beams in an array to the receiver. The receiver contains photoelectric cells that can easily absorb these array of light beams. Whenever an object is seen breaking one or more beams, the guarded equipment is notified with a signal to stop.

The beam of light produced from the transmitter is sequenced, in a steady progression, and is pulsed at a particular recurrence. The receiver is optimized to accept only a specific frequency and pulse from its respective transmitter. This helps in rejecting infrared light that is spurious and in this way improves their reasonableness as segments inside a security framework.

Generally, it is seen that a safety relay is connected with these light curtains that help in nullifying motive power from the hazard. Safety relays can be given muting usefulness which empowers the brief disabling of the security capacity to enable articles to go through the light curtains without stumbling the safety relay. This is especially valuable for hardware which has a few Semi-Automatic processes.

Applications of Safety Light Curtains: Point of Operation Vs Perimeter

Industrial facilities and manufacturers utilize light curtains for safety in 2 general situations i.e. Point of Operation & Perimeter. Let's discuss them in brief.

• Point of Operation

In this case, the individual positions the light curtains at the point of material handling, let's say under a hydraulic press. It is done with an only intention to make sure that nobody enters the danger area while the machine is being operated.

• Perimeter

Conversely, perimeter guards allude to depicting an entire working space or room, let's say for robotic arms. It makes sure that no object or person comes in the boundary of the movement of the machine.

Advantages of Safety Light Curtain

Light curtains provide several advantages over physical barriers, such as.

1. It's quite easy to access machine guarded by safety light curtain rather by a physical barrier.
2. To perform semi-automatic processes and routine maintenance can be done efficiently.

Hope you liked the above article on safety light curtains. Brands that manufacture them are Panasonic, Omron, and Honeywell. Make sure to follow them using the links as provided.

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