Voltage stabilizer Vacuum AC contactor works

Vacuum contactor vacuum interrupter media as its main contacts sealed in mcb circuit breaker‍ a special vacuum arc tube. When the operating coil is energized, the armature pull, in the role of the contact spring and vacuum autistic force contact closure; when operating coil power, the reaction force of the spring force to overcome the vacuum autistic armature release, contacts open. When the contactor breaking current, the contact gap will be formed from a metal vapor to form platinum scale, affecting the life of the contactor.

AC contactor selection

AC contactor selection, Circuit Breakers‍ the selection should be reasonable and based on the type of work load parameters. Specifically divided into the following steps:

1. Select the type of contactor

AC contactor according to the type of load is generally divided into Type I, II, III and IV, respectively denoted AC1, AC2, AC3 and AC4. A corresponding class of AC contactor control object is no sense or micro sense load, such as incandescent, resistance furnace; II AC contactor for wound rotor induction motor starting and stopping; three AC contactor typical use is squirrel cage induction motor running and running carve off; four AC contactor for Electric transformer‍ squirrel cage induction motor starting, reverse brake, reverse and jog.

electric energy meter Select the contact's ratings

According to the controlled object and operating parameters such as voltage, current, power, frequency and operating system, such as determining the power transformers‍ contactor ratings.

1) contactor coil voltage, should generally be lower as well, so that contact can reduce the insulation requirements, while also safer to use. However, in order to facilitate and reduce the equipment electric energy meter‍, often by the actual grid voltage selection.

2) operation of the motor frequency is not high, such as compressors, pumps, fans, air conditioners, punch, etc., contact rated load current is greater than the rated current can be. Contactor type can be used CJl0, CJ20 and so on.

3) heavy duty motors, such as machine main motor, lifting equipment, winches, crushers, etc., the average operating frequency of more than 100 times / min, start running, jogging, forward and reverse brake, reverse braking, etc. state, the choice CJl0Z, CJl2 type of contactor. In order to ensure the electrical life, make contacts with derating. When selected, the contactor rated current greater than the motor rated current.

4) special heavy duty motor, such as printing presses, boring, etc., high operating frequency, up to 600 to 12,000 times / h, often running start, reverse brake, reverse and other state, mcb circuit breaker‍ according to the electrical contacts roughly life and starting current selection, model selection contactor CJl0Z, CJl2 so on.

5) AC circuit capacitors into the grid or the removal from the grid, the contactor closing capacitor selection should consider the impact of current. 1.5 In general, the contactor rated capacitor current can be rated current selection, model selection CJ10, CJ20 and so on.

6) When the transformer with contactor control, you should consider the size of the inrush current. AC arc welder for example, resistance welding machines, etc., generally can be 2 times the rated current of the transformer selected contact, model selection CJl0, CJ20 and so on.

7) For the electric equipment, such as a resistance furnace, electric heaters, etc., cold resistance load is small, so the starting current corresponding to a large number. May not consider (starting current) when selecting contacts, press the load rated current selection. Models can be used CJl0, CJ20, etc.

8) Because of the gas discharge lamp starting current, starting a long time, for the control of lighting equipment, according to the rated current of 1.1 to 1.4 times the selected AC contactor, models available CJl0, CJ20 and so on.

9) Contactor contactor rated current is under long-term maximum allowable current, duration ≤8h, and installed in the open control panel, if the cooling conditions are poor, the selection of contactors, the contactor rated by 110% to 120% of rated load current selection. For the motor to work long hours, due to the oxide film is no chance to get it cleared, the contact resistance increases, resulting in contact heat exceeds the allowable Air circuit breaker‍ temperature rise. When the actual selection, you can contact the rated current is reduced by 30% using.

Voltage stabilizer Operational use Eight hour working day

AC contactor which is the basic duty. Contactor Conventional thermal current parameters is determined Click duty, under normal circumstances the specifications of various series contactors are Inverter Power Supply‍ suitable for eight hour working day. Such duty contactor which closes the main contact in the case of thermal equilibrium can be achieved by the rated current, but after eight hours should be divided.

Uninterrupted work system

Such work system is a long-term work system, that is the main contacts remain closed for the duration of carrying a steady current of more than eight hours (a few weeks or even years) is not breaking current working system. Contacts in the contact oxidation and long-term accumulation of dust in working condition electric transformer‍ unchanged easy voltage stabilizer, these factors will lead to the deterioration of thermal conditions, phase to phase, relatively insulated reduce creepage phenomenon even prone to short-circuit. When the conditions required to work in this type of work contactor system, AC contactor must derating or special design, easy to gather dust should use, creepage distance between the larger models. Dusty and corrosive gas environment should pay special attention to this issue.

Short-time working

In contact with the main contact system under this type of work remain closed is not enough time to make contacts to reach thermal equilibrium, there is no load load periods separated by periods, while the load time enough to make contact with the temperature back to the initial state temperature (ie cooling medium temperature). Energy Meter‍ Short-time working contactor contacts energizing time standard value 3,10,30,60 and 90min.

electric energy meter Intermittent periodic duty

Intermittent duty cycle is repeated short-time working means contactor closing and opening times are too short to make contacts in the working system to reach thermal equilibrium. mcb circuit breaker‍ Obviously the main factors affecting the life time of such contacts is the cumulative number of operations. The main parameters describing intermittent duty cycle is powered sustained rate and operating frequency, power continued to rate the standard value of 15%, 25%, 40%, 60% of four, the operating frequency is divided into eight (1,3,12 , 120,300,600,1200) electric energy meter, each level figures mean that the number of hourly operating frequency of the contactor rated. Typically operating frequency of 100 times / h or more devices are heavy duty equipment, machine tools typical equipment (vehicles, drilling, milling, grinding), lifting equipment, mill equipment, centrifuges, coking industry, coke oven car is heavy intermittent periodic duty tasks. Operating frequency Inverter Power Supply‍ over 600 times / h belongs to special equipment heavy duty equipment, such equipment is mainly some devices similar to my company unloading port lifting equipment and machine rolling on.

Voltage stabilizer Different requirements analysis

Different operating system of exchanges and contacts made entirely different requirements, focusing face when considering the choice of a different Switchgear & Substation‍ nature. When the "voltage stabilizer" and "short-time working" equipment selection is subject to fewer constraints contact, just consider the contactor rated operating current can be greater than the actual, proper equipment is important when you put a little margin. The ability to "stop work" system should first consider equipment selection contacts Dust-creepage prevent overheating, compact structure should not use contactor (circuit breaker for use when necessary). To prevent overheating, the contactor should enlarge the Power Supply‍ capacity of more than 20% of large chemical plant electrical equipment mostly this is the case. We must first consider the mechanical life of electrical contacts and operating mechanism of life belonging to heavy duty and special heavy task of "intermittent periodic duty" equipment selection contactors should be used CJ12 series (especially suitable for winding motor), CJ20 series or series of vacuum contactors, due to derating can greatly improve the electrical contactor life can easily be selected as the starting mcb circuit breaker‍ current of the motor contactor rated current to improve the safety and reliability of production unit.