The Development History of AC Contactor
In 1924, the world’s first contactor was made.
In 1935, the world’s first monomer contactor was made.
In 1960, the world’s first motor starter was made.
In 1973, the world’s first modular contactor was made.
In 2003, TeSys U series products were armed with more functions than before.
In 2000, TeSys series products was made, continuing the excellent properties of D2 series products.
In 1993, GV2 series products realized the starting scheme of two-element motor.
In 1990, the legendary D2 series products had monopolized the global market for more than 10 years.
Model K
0.06 —> 5.5 kW
Model D
0.06 —> 75 kW
Model F
15 —> 450 kW
Model B
220 —> 900 kW
Model GV : GV2
0.06 —>15 kW
GV3P/L
5.5 —> 30 kW
TeSys U Starter
0.06~15 KW
TeSys U Controller
0.06~450 KW
Vario
3~45 KW
Model K
0.06 —> 5.5 kW
Model D
0.06 —> 18.5 kW 18.5 —> 45 kW 55—> 75 kW
Model F
18.5—>315 kW
EOCR
0.1 —> 37KW
LT6
5/25A
The Application of AC Contactor
1)Application
AC contactor is an electrical appliance suitable for switching on and off the circuits and AC motors from the long distance.
It is mainly used to control the AC motor in starting, stopping, reversing and regulating speed, and it can also combine with thermal relays or other appropriate protective devices to protect motors from the overload or phase failure likely occurring. It can also be used to control other power loads, such as electric heaters, electric lighting machines, electric welding machines, capacitor banks, etc.
2)Classification
According to the types of charged current, contactors can be divided into AC contactors and DC contactors.
Anssin’s products on contactors are mainly AC contactors.
Models and Meanings of AC Contactor
Main Parameters and Performance of AC Contactor
AC Contactor Applied in Circuit with 220V
AC Contactor Applied in Circuit with 380V
Structure of Magnetic AC Contactor
Structure:
The contactor is mainly composed of the electromagnetic system, contact system, arc extinction system and other parts.
① Electromagnetic system: Electromagnetic system includes electromagnetic coil and iron core. It is an important part of contactor, which drives the closing and opening of contacts.
② Contact system: The contact is the executive part of the contactor, including main contact and auxiliary contact. The main contact is used to connect and disconnect the main circuit and control large current, while the auxiliary contact is used to meet the requirements of various control modes in the control circuit.
③ Arc extinction system: The arc-control device is used to ensure that the arc generated can be extincted effectively and the damage to the contacts from the arc can be reduced when the contact disconnects the circuit.
④ Other parts: insulating shell, spring, short circuit ring, transmission mechanism, etc.
How AC Contactor Works？
When the coil is energized, the armature is attracted, and the suction of the electromagnetic system overcomes the reaction force from the antagonistic spring and the contact spring. At the same time, the moving contact and the static contact are connected, with the main circuit connecting.
When the coil is switched off, the armature and moving contact move under the influence of reaction force, and the contact disconnects, generating an arc. Driven by the electrical force and aerodynamic force of the contact circuit, the arc is extincted after being strongly cooled and deionized in the arc-extinguishing chamber, and then the main circuit is switched off.
Installation Method
Guide rail type installation (DIN Rail)
Contact parameters:
The clearance between open contacts refers to the shortest distance between the moving and static contacts when the contact is disconnected. Its value is determined by whether it can withstand the overvoltage possibly happened in the circuit and whether the arc can be extincted smoothly.
• Overrun refers to the distance that the moving contact can still move when the static contact is moved away, after the contact moves to the closed position. Its value is determined by the electrical corrosion the contact suffered within the limitation.
• Initial pressure refers to the positive pressure acting on the contact when it is just closed.
• Terminate pressure refers to the pressure happened at the termination position for contact closing, and its value is determined by many factors, such as the increase of temperature, fusion welding, et
Contact material
Electromagnetic Coil
Electromagnet and its Application
The electromagnet is made of silicon lamination. The iron core is divided into moving and static iron cores. Generally, the static iron core is fixed. When the contactor coil is energized, the moving core moves to the static core under the influence of electromagnetic attraction; when the coil is switched off, it returns to its original position under the influence of the reset spring. Electromagnet converts electro-magnetic energy into mechanical energy. It uses the coil to produce a magnetic field in the iron core, attracting the armature and driving the mechanical parts to complete the expected actions.
Structure of Electromagnet
Plastic Parts
Stamping Parts
Usages and Typical Load of Contactor
1）Usages
2）Typical load
Between different electrical equipment, there are big differences in the load properties and current changes in the process of on and off, so the requirements for different contactors are different. The loads commonly used are as follows:
2.1）Electric heating element load
For the wire wound resistor used in the electric heating load, its connecting current can reach 1.4 times of the rated current, such as the in-indoor heating supply, electric oven, air conditioning and other equipment. If the network voltage increases by 10%, the working current of the resistor will increase accordingly. Therefore, it should be considered when selecting the rated working current of the contactor. Such kind of loads is classified in the AC-1 usage.
2.2）Lighting device
When the incandescent lamp load is switched on in the illumination equipment, a large impulse current is generated, which is about 15 times of the rated current. If the permissible voltage increases by 10%, the current will increase accordingly, and its usage is divided into AC-5b. Different lighting equipment have different impulse current value and starting time when they are switched on, and the load power factor is not equal to 1. They are uniformly divided in AC-5a.
2.3）Low-voltage transformer load
When the low-voltage transformer is connected, it will produce a peak current within the very short duration, which is up to 15-20 times of the transformer’ s rated current. It is related to the winding arrangement and core properties of the transformer.
For example, for the transformer used on the electric welding machine, the operation is to connect the power supply by short circuit through the welding rod from the secondary side of the transformer. When using the electric welding machine, it often produces the sudden strong current, which makes the switching device on the primary side of the transformer bear great stress.
In this case, the parameters and operating conditions must be known, such as the rated working current output by the transformer, the short-circuit current and the welding frequency when the welding rod is shorten. This usage is classified in AC-6A.
2.4）Capacitor Load
The transient charging process occurs when the capacitor is switched on, and the charging current can reach a high value, accompanied by the oscillation of frequency increasing from hundreds to thousands of Hz.
Therefore, it has severe requirements for switching devices.
The amplitude and frequency of the current from the connected capacitor are determined by the mains voltage of the circuit, the capacity of the capacitor and the reactance value in the circuit, and are related to the cross section and length of the infeed transformer and connecting conductor.
In order to switch capacitors economically and prevent the contact of switching appliances from being connected and welded under adverse working conditions, additional inductance or resistance can be connected in series in capacitors and circuit branches to limit the current and reduce the influence on the mains grid when connecting the circuit. This usage is classified in AC-6B.
2.5）Motor load
Low voltage motor is one of the most commonly used loads. Wound-rotor induction motor and asynchronous motor are common types in AC motor.
When the wound-rotor induction motor starts, a resistor connected in the rotor circuit limits the starting current. However, the starting time of different loads is different. The heavier the load is, the longer starting time it takes. The contactor used for switching wound-rotor induction motor belongs to AC-2 usage.
Generally, asynchronous motor adopts direct starting. After the impact of starting current reduces, the stable current Ie flows. Generally, the starting current (effective value) IA on asynchronous motor is 4 ~ 8 times of the rated current of motor. The no-load current IO of the motor equals to (0.95 ~ 0.2) Ie. The starting time TA under normal load is less than 10 seconds, and TA can be greater than 10 seconds when carrying heavy load to start.
The contactor used to switch the normal starting and breaking in operation of asynchronous motor belongs to AC-3 usage.
In asynchronous motor, for the contactor operating under the condition of normal starting and taking reverse connection braking, reverse operating or inching at the same time, its connecting and breaking current both are the starting current of motor. The switching devices of this working usage belongs to AC-4, which has more strict requirements than that of AC-3 working usage.