HAVELLS Contactor Price List w.e.f 5th September 2013 (VIEW) HAVELLS Customer Care No:+91-120-4771000
L&T Contactor Price List w.e.f 1st JANUARY 2015 (VIEW) L&T Customer Care No:18002094545
A contactor is an electrically controlled switch used for switching a power circuit, similar to a relay except with higher current ratings. A contactor is controlled by a circuit which has a much lower power level than the switched circuit. Contactors come in many forms with varying capacities and features. Unlike a circuit breaker, a contactor is not intended to interrupt a short circuit current. Contactors range from those having a breaking current of several amperes to thousands of amperes and 24 V DC to many kilovolts. The physical size of contactors ranges from a device small enough to pick up with one hand, to large devices approximately a meter (yard) on a side.
Current Rating of Contactor
The current rating of the contactor depends on utilization category. Example IEC categories in standard 60947 are described as: AC-1 - Non-inductive or slightly inductive loads, resistance furnaces
Operating Principle of Contactors
A contactor works on the principle of Electro-magnetism. IT comes under the category of switch gears and all the switch gears perform the same function of Switching.
A contactor consists of mainly 2 parts-Fixed and movable jaws. the fixed jaws are firmly connected with the circuit and is a provided with a COIL having movable jaw as soon as current is allowed to flow from the circuit the COIL gets charged and due to electromagnetic effect it attracts the
movable metal jaw, thus the circuit is complete with the CONTACT provided by the movable jaw. This is the functioning of contactor. When current through the circuit ceases, coil demagnetizes and movable jaw is pulled apart .
Applictions of Contactors
Contactors are often used to provide central control of large lighting installations, such as an office building or retail building. To reduce power consumption in the contactor coils, latching contactors are used, which have two operating coils. One coil, momentarily energized, closes the power circuit contacts, which are then mechanically held closed; the second coil opens the contacts.
A magnetic starter is a device designed to provide power to electric motors. It includes a contactor as an essential component, while also providing power-cutoff, under-voltage, and overload protection.
Vacuum contactors utilize vacuum bottle encapsulated contacts to suppress the arc. This arc suppression allows the contacts to be much smaller and use less space than air break contacts at higher currents. As the contacts are encapsulated, vacuum contactors are used fairly extensively in dirty applications, such as mining.
Vacuum contactors are only applicable for use in AC systems. The AC arc generated upon opening of the contacts will self-extinguish at the zero-crossing of the current waveform, with the vacuum preventing a re-strike of the arc across the open contacts. Vacuum contactors are therefore very efficient at disrupting the energy of an electric arc and are used when relatively fast switching is required, as the maximum break time is determined by the periodicity of the AC waveform.