Dry-type Air Core Reactors

1.The Character of Dry-type Air Core Reactors
(1)The reactor is enclosed by epoxy resin impreg-nated long glass fiber is composed of several enclosures of coils.
(2)The coil is insulated by polyester film, which has good capability of insulation.
(3)The reactor is covered by organic silicon paint against ultraviolet radiation and has fine performance operating outdoors.
(4)Between enclosure of coils, supports made of polyester glass fiber are used for axial heat radiator. This construction has a better property of heat radiation.
(5)When making calculation of temperature rise, we consider of the highest temperature of the hot-test spot and keep preferable margin. It can guarantee the long-term safe operation of reactors.
(6)Because it has a structure of multiple conductors wound in parallel and multiple enclosures, there is no axial stress. Under the steady working voltage, voltage along height of coils arranges equally. 
(7)As the reactor is enclosed by epoxy resin impregnated long glass fiber, after curing, the coil has a compact structure. The noise level is less than 60 dB during twenty years of its service.
(8)The reactor adopts small round section aluminum wires (φ1.6-φ4.5) as coil conductor, thus effectively reduce vortex losses of coils under harmonic waves.
(9)For the reactor is enclosed by epoxy resin impregnated long glass fiber, the great mechanic forces caused by short-circuit is sustained by reactor enclosures. The whole coil has better ability against short-circuit.
(10)The joint is welded by argon arc and there is no fastener on mechanical parts. This kind of structure leads to safer operation.
(11)The structure is simple and compact. The reactor can operate outdoors with convenient maintenance.
(12)The unit weight contains larger capacity in kilo Var.
2. Classification and Application of Dry-type Air Core Reactors
The connection of reactor comprises series connection and shunt connection. Series-connected reactor usually functions as current limitation and shunt-connected one usually functions as var compensation.
Several common-used reactors are listed below:
(1) Series Reactor. They are equipped in capacitor banks circuit and restrain surge current. During switching they combine with capacitor banks to form filter circuit so as to filter specific harmonic waves.
(2) Shunt Reactors. They apply to super high voltage and long distance power transmission system. They are connected to tertiary winding of transformer. They compensate capacitive current in power lines and limit system over voltage and operating over voltage, thus lower system insulation level and guarantee reliable operation.
(3) Current Limiting Reactors. They restrain short circuit and lower it to a proper level for the equipment.
(4) Neutral point Earth-connected Reactors (i.e. Arc Suppression Coils). They restrain accident current from power transmission system to earth.
(5) Current Blocking Reactors. They prevent harmonic waves from entering into power system so as to protect equipment from being harmed by them.
(6) Filter Reactors. They are often series connected to capacitor banks circuit. They provide an LC resonant circuit of low impedance for a certain harmonic wave to filter waves.
(7) Partite Reactors. They are series connected to systems to restrain accident current. They appear with low impedance at normal operation and with high one at accident.
(8) Static Var Compensation Reactors. They apply to phase control thristor equipment for fast var compensation (SVC)
(9) Balance Reactors. They comprise balance load with inductive electric furnace and capacitor in three-phrase power.
(10) Start-up Reactors. They apply to start-up at low voltage for large AC motor.
(11) Smoothing Reactors. They apply to high volt-age DC power transmission (HVDC) system and large power DC electric gearing. They lower impulsive current component in DC circuit to keep DC current smooth.
3.The Service Condition of Dry-type Air Core Reactors
(1) Location: indoor or outdoor
(2) Environment temperature: -40℃～+45℃
(3) Altitude above sea level: 1000meters. A statement is required if operating above 1000meters.
(4) The location should have no harmful gas or vapor or electric and explosive dust.