Arc suppression
Encyclopedia
Arc suppression is a method of attempting to reduce to near elimination the luminous discharge of electrical current (scientifically known as plasma
), between two electrode
s, through a gas (most commonly air). This luminous discharge is a surge of highly energized electrons and ions, and is commonly referred to as an electric arc
.
, arc flash protection, electrostatic processes where electrical arcs are not desired (such as powder painting
, air purification
, PVDF
film poling) and contact current arc suppression. In industrial, military and consumer electronic design, the latter method generally applies to devices such as electromechanical power switches, relays and contactors. In this context, arc suppression refers to the concept of contact protection.
The energy contained in the resulting electrical arc is very high (tens of thousands of degrees Fahrenheit), causing the metal on the contact surfaces to melt, pool and migrate with the current. The extremely high temperature of the arc cracks the surrounding gas molecules creating ozone, carbon monoxide, and other compounds. The arc energy slowly destroys the contact metal, causing some material to escape into the air as fine particulate matter. This very activity causes the material in the contacts to degrade quickly, resulting in device failure.
Arc suppression is an area of interest in engineering because of the destructive effects of the electrical arc to electromechanical power switches, relays and contactors’ points of contact.
It is not possible to achieve a complete elimination of an arc between contacts of electromechanical power switches, relays and contactors. The arc has to be detected first before it can be suppressed. The following components, if or when added to the relay coil or contact, do neither significantly influence the creation nor suppress the arc between the contacts of the electromechanical power switches, relays and contactors: capacitor
s, snubber
s, diode
s, Zener diode
s, transient voltage suppressors, varistor
s.
Plasma
Plasma may refer to:* Blood plasma, the yellow-colored liquid component of blood, in which blood cells are suspended* Plasma , an ionized state of matter similar to a gas...
), between two electrode
Electrode
An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit...
s, through a gas (most commonly air). This luminous discharge is a surge of highly energized electrons and ions, and is commonly referred to as an electric arc
Electric arc
An electric arc is an electrical breakdown of a gas which produces an ongoing plasma discharge, resulting from a current flowing through normally nonconductive media such as air. A synonym is arc discharge. An arc discharge is characterized by a lower voltage than a glow discharge, and relies on...
.
Uses
There are several possible areas of use of arc suppression methods, among them metal film deposition and sputteringSputter deposition
Sputter deposition is a physical vapor deposition method of depositing thin films by sputtering, that is ejecting, material from a "target," that is source, which then deposits onto a "substrate," such as a silicon wafer...
, arc flash protection, electrostatic processes where electrical arcs are not desired (such as powder painting
Powder painting
Powder Painting is the art of using ground glass in powdered form to create kilnformed glass art. The process differs from enameling in many respects. Firstly, the powder is actually ground glass typically from a single manufacturer who supplies an extensive color palate...
, air purification
Air purifier
An air purifier is a device which removes contaminants from the air. These devices are commonly marketed as being beneficial to allergy sufferers and asthmatics, and at reducing or eliminating second-hand tobacco smoke...
, PVDF
Polyvinylidene fluoride
Polyvinylidene fluoride, or PVDF is a highly non-reactive and pure thermoplastic fluoropolymer.PVDF is a specialty plastic material in the fluoropolymer family; it is used generally in applications requiring the highest purity, strength, and resistance to solvents, acids, bases and heat and low...
film poling) and contact current arc suppression. In industrial, military and consumer electronic design, the latter method generally applies to devices such as electromechanical power switches, relays and contactors. In this context, arc suppression refers to the concept of contact protection.
Arc suppression as contact protection
Every time an electrical power device (for example: heaters, lamps, motors, transformers or similar power loads) turns on or off its switch, relay or contactor transitions either from a closed to an open state (break arc) or from an open to a closed state (make arc & bounce arc), under load, an electrical arc occurs between the two contact points (electrodes) of the electromechanical power switch, relay or contactor. The break arc is typically more energetic and thus more destructive.The energy contained in the resulting electrical arc is very high (tens of thousands of degrees Fahrenheit), causing the metal on the contact surfaces to melt, pool and migrate with the current. The extremely high temperature of the arc cracks the surrounding gas molecules creating ozone, carbon monoxide, and other compounds. The arc energy slowly destroys the contact metal, causing some material to escape into the air as fine particulate matter. This very activity causes the material in the contacts to degrade quickly, resulting in device failure.
Arc suppression is an area of interest in engineering because of the destructive effects of the electrical arc to electromechanical power switches, relays and contactors’ points of contact.
Effectiveness
The efficacy of an arc suppression solution can be assessed, by comparing the arc intensity with the help of the following methods:- Visual Inspection of the arc: The electrical arc can be visually observed on an electromechanical power switch, relay and contactor, with visible contacts, while the contacts are opening and closing under load.
- Graphical representation of measurements obtained by an oscilloscope: The electrical arc can be observed by using an oscilloscope to trace the voltage wave form across the contact terminals while the contacts are opening and closing under load.
It is not possible to achieve a complete elimination of an arc between contacts of electromechanical power switches, relays and contactors. The arc has to be detected first before it can be suppressed. The following components, if or when added to the relay coil or contact, do neither significantly influence the creation nor suppress the arc between the contacts of the electromechanical power switches, relays and contactors: capacitor
Capacitor
A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...
s, snubber
Snubber
A snubber is a device used to suppress voltage transients in electrical systems, pressure transients in fluid systems, or excess force or rapid movement in mechanical systems.-Electrical systems:...
s, diode
Diode
In electronics, a diode is a type of two-terminal electronic component with a nonlinear current–voltage characteristic. A semiconductor diode, the most common type today, is a crystalline piece of semiconductor material connected to two electrical terminals...
s, Zener diode
Zener diode
A Zener diode is a special kind of diode which allows current to flow in the forward direction in the same manner as an ideal diode, but will also permit it to flow in the reverse direction when the voltage is above a certain value known as the breakdown voltage, "Zener knee voltage" or "Zener...
s, transient voltage suppressors, varistor
Varistor
A varistor is an electronic component with a "diode-like" nonlinear current–voltage characteristic. The name is a portmanteau of variable resistor...
s.
Common devices
Common devices used to attempt arc suppression today are: capacitors, snubbers, diodes, Zener diodes, varistors, transient voltage suppressors, in-rush current limiters, PTC resistors, NTC resistors, voltage-dependent resistors. Though common in use today, none of these solutions will actually suppress an electrical arc (per above verification methods). Contact arc suppression solutions that are considered more effective:- Two-wire contact arc suppressor
- Solid state relays are not electromechanical, have no contacts, and, thus, do nor create electrical arcs.
- Hybrid Power Relays
- Hybrid Power Contactors
Further reading
- Relays - Frequently Asked Questions
- Arc suppression articles on Institute of Electrical and Electronics EngineersInstitute of Electrical and Electronics EngineersThe Institute of Electrical and Electronics Engineers is a non-profit professional association headquartered in New York City that is dedicated to advancing technological innovation and excellence...
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