Polymer film capacitors, or film dielectric capacitors or plastic film capacitors or film capacitors are generally known as power film capacitors and "film caps". These are those electrical capacitors having an insulating plastic film (dielectric).

Depending on the needed dielectric strength, the dielectric films are drawn into a much thinner thickness and are then offered with electrodes. The electrodes used in these capacitors might be metalized zinc or aluminum applied legitimately to the plastic film’s surface, or a different metallic foil. 2 of the conductive layers are winded in a cylindrical shape, generally flattened to decrease the requirement of mounting space on a printed circuit board. They may be also stacked as multiple layers to form the body of a capacitor. Along with electrolytic capacitors and ceramic capacitors, film capacitors are the most popular and common capacitors type for utilizing electrical equipment. They are utilized in several DC and AC electronics and microelectronics circuits.

Though the constructions and materials utilized for larger power film capacitors are very much the same as that of ordinary film capacitors, capacitors coming with a very high rating of power for power system applications and electrical installations are often categorized separately due to some historical reasons. Today several modern electronic equipment have got the ability to manage the level of high powers that was earlier one of the biggest constraints of components related to "electrical power". The difference between "electrical" and "electronic" rating of power has become less distinct. In the earlier time, the line of boundary between these two families was approximately 200 Volt-Ampere but the modern ones are well made to manage high power levels.

Example manufacturing process

The example discussed below describes a common assembling process stream for wound metalized plastic film capacitors.

• Metallization and Film stretching – To uplift the value of capacitance of the capacitor, the plastic film is drawn utilizing an exceptional expulsion procedure of bi-pivotal extending in transverse and longitudinal direction.
• Film slitting - The mother folds are cut into little portions of plastic film in the necessary width.
• Winding – 2 films are then made to roll together into a cylindrical winding.
• Flattening – The winding is then generally flattened into the shape of an oval by utilizing mechanical pressure.
• Application of Metallic Contact layer – A liquefied contact metal like zinc or tin is used to cover up the projecting end electrodes.
• Healing – Healing is done by applying an absolutely adjusted voltage over the electrodes of the winding with the goal that any current deformities will be "consumed with extreme heat".
• Impregnation – For protection from moisture, the winding is made to impregnate using silicone oil (insulating fluid).
• Attachment of terminals – The capacitor’s terminals are welded on the end metal contact layers.
• Coating – Succeeding the attachment, the body of the capacitors is dunked into a protective coating.
• Electrical final test – Before the use of every capacitor it is important to test it for the desired parameters, like, Impedance, Capacitance or dissipation factor.

Brands that manufacture film capacitors are Kemet, Panasonic, and EPCOS. 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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A photo eye or a photoelectric sensor is a gadget that helps in discovering the present and absence of the object as well as its distance by utilizing a light transmitter, generally infrared, with a photoelectric receiver. They are most commonly used in manufacturing in the industry.

Types

There are 3 types of Photoelectric Sensors. Let’s have a look at them.

A photoelectric sensor that is self-contained comes with the optics in addition to the electronics. It needs only a source of energy. The sensor does its own output switching, amplification, modulation, and demodulation. Some sensors that are self-contained also supports an option for counters or built-in control timers. Because of the advancement in the tech world, today, self-contained photoelectric sensors are reduced in sizes.

Remote photoelectric sensors that are utilized in remote sensing comes with only the optical part. The hardware for amplification, output switching and power input are situated elsewhere, generally in a control panel. Thus allowing the sensor to get very small. In addition to that, the controls of the sensor are increasingly available, since they might be greater.

When space is one of the constraints or the environment is excessively hostile for using remote sensors, we take fiber optics into consideration. Fiber optics are latent mechanical detecting segments. They can be utilized either with self-contained sensors or with remote ones. They have neither any moving part nor comes with any electrical circuitry. It can pipe light safely into and out of any hostile environment.

Modes

There are 3 different modes of photoelectric sensors. They are as follows:

• Opposed (through-beam)

Pros:

1. The sensing range is the longest.
2. It is mostly accurate.
3. It is very much reliable

Cons:

1. It is important that it should get installed at 2 points in the system i.e. receiver as well as an emitter.
2. It is a bit costly as it required a separate receiver and emitter.

• Retro-Reflective

Pros:

1. Its sensing range is much better than that of diffuse.
2. It is slightly less accurate than through beam.
3. It is very much reliable.

Cons:

1. Its sensing range is lesser than through beam.
2. It is a bit more costly than diffuse
3. It is important that it should get installed at 2 points in the system i.e. reflector as well as the sensor.

• Diffuse (Proximity Sensing)

Pros:

1. It needs to be installed only at one point.
2. It is much cheaper than reflective as well as through-beam.

Cons:

1. It requires more setup time.
2. Accuracy level is lesser than retro-reflective or through-beam.

This was all we have regarding photoelectric sensors. Hope that you enjoyed reading through the article. Brands that manufacture photoelectric sensors are Omron, Panasonic, and Sick. Make sure to follow them using the links as provided.

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A counter or a tachometer is an instrument that helps in measuring the speed of rotation of a disk or shaft, like that present in a motor. This device generally shows the RPM (Revolution Per Minute) on a calibrated analogue dial. The digital displays are getting much popular these days.

The word speedometer as well as tachometer have the same meaning i.e. a device used in measuring the speed. But by convention in the world of automobiles, one is used for representing the speed of the vehicle and the other one represents that of the engine.

The 1^st made tachometer depended on estimating the Centrifugal force. Its operation was similar to the Centrifugal governor. The person who invented this device was Dietrich Uhlhorn, a German Engineer, in 1817. From 1840, this device is utilized to calculate the engine’s speed.

Revolution counters or tachometers present in aircraft, cars and other automobiles show the rotation rate of the crankshaft of an engine. It has also got a marking that points to the range that is safe for the rotation speed. This helps the driver in choosing the right gear and throttle setting. Overheating and inadequate lubrication is the major consequence of their prolonged use at high speed.

In analogue tachometers, if the speed rises more than the safe operating speed then it is displayed by a zone of the gauge with a red mark. Thus, offering to ascend to the declaration of “redlining” an engine - firing it up to the most extreme safe point of confinement. The modern cars used these days also come with this red mark in their tachometer. However, they are of no use as their engines come with a limiter which automatically limits its speed to prevent the car from any damage. Diesel engines with conventional mechanical injector frameworks come with an integral speed limiter which stops the engine to speed up. Thus the tachometer used in them lacks redline.

The trucks and tractors come with a tachometer that has a green arc in them. This green arc lets the driver know the speed at which the engine is producing the maximum torque. Some tractors also come with a PTO (Power Take-Off). The tachometers in them help in letting the driver accustomed to the speed of the engine needed to rotate the PTO at the standardized rate. Tractors having more than one ‘road gear’ often have tachometers with multiple speed scale. The green arc is said above is also present in the tachometer of an aircraft to show the cruising speed range of their engine.

Traffic Engineering

From the above discussion, it is clear that tachometers help in estimating the volume (flow) and speed of the engine. A vehicle is fitted with a sensor and conducts "tact runs" that keep a record of the traffic information. The information gathered here is a complement to loop detector data. To get measurably huge outcomes needs a large number of runs. Nonetheless, due to the cost and spacing tach runs is a popular practice.

This was all we had about counters and tachometers. Brands that manufacture them are Panasonic, Omron, and Crouzet. Make sure to check them out through the links as provided.

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A varistor is an electrical device having an electrical resistance that differs with the potential applied to it. A varistor is popularly known as Voltage Dependent Resistor (VDR). It possesses a non-ohmic and non-linear Current-Voltage characteristic which is equivalent to a diode. Unlike the diode, it has a similar characteristic for the flow of both directions of current. Customarily, varistors were made by joining 2 rectifiers i.e. either the germanium-oxide or the copper-oxide rectifier in a configuration that is anti-parallel. The electrical resistance of the varistor is high at low voltage but as the voltage increases the resistance decreases. The varistors that are used presently are fundamentally dependent on sintered ceramic metal-oxide materials. On a microscopic scale, it shows directional behavior. This category is popularly known as MOV or Metal Oxide Varistor.

Varistor serves as a compensation and a control element in the electrical circuit either to defend against excess voltage or to offer optimal operating conditions. When utilized as defending devices, they shunt the current established by the exorbitant voltage away from touchy segments when activated.

Composition

As said earlier, the newest form of varistor that is used is the Metal Oxide Varistor. This kind of varistor is constituted by a ceramic mass of zinc oxide grains with metal oxides (like a small quantity of cobalt, bismuth, manganese oxides) placed in the middle of 2 metal plates, which comprise the device’s electrodes. A diode junction is formed between each grain and its neighbor.

When the electrodes are given a small potential difference then only a small amount of current flows through the diode junction which is a result of reverse leakage. On the other hand when a large voltage is applied on the electrodes a large amount of current flows, as the diode junction separates itself because of the combination of electron tunneling and thermionic emission. The consequence of the above-said behavior is a non-linear Current-Voltage characteristic where the MOV possesses a low resistance at high voltage and high resistance at low voltage.

Voltage Rating

MOVs are categorized by the range of voltage that they can endure without damage. The other parameter is the varistor’s breakdown voltage, maximum current, energy rating in joules, response time and operating voltage.

The rating of energy is regularly characterized utilizing institutionalized transients like 10/1000 microseconds or 8/20 microseconds. Here 10 microseconds are the front time of the transient and 1000 microseconds is the time of half value.

Capacitance

The range of capacitance for varistors which are consumer-sized i.e. 7 to 20mm in diameter is from 100pF to 2,500pF. Varistors that are used in micro electric protection have low capacitance like around 1pF. You can get this kind in cellular phone. These varistors having low capacitance cannot withstand the flow of a large amount of current as the PCB mount size is compact.

Response time

The response time of the MOV isn't institutionalized.

Hope you liked the article on Varistors. Brands that make them are Littelfuse, EPCOS, Panasonic. You can refer to them using the links as provided. Thank you for reading.

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