AC Magnetic Contactor

Product Description

High quality AC Magnetic Contactor made by SPX Electric is the physical starting point for all automation controls. After the PLC issues the command, the AC electromagnetic contactor completes a crucial leap from weak control signals to strong electric drive before the motor actually rotates. It is not the most complex component, but it is an irreplaceable and time hardened reliable executor in industrial power systems.
By driving mechanical contacts with electromagnetic force, complete electrical isolation is established between the control coil (low-voltage side) and the main circuit (high-voltage high current side). This fundamentally avoids the risk of high voltage entering the control system, ensuring the safety of personnel and sensitive equipment such as PLCs.
The mechanical action of the contact point is usually accompanied by a clear and audible "click" sound, and most products have a visual position indicator window, providing direct and reliable physical state feedback.
The current at the moment of starting the motor can reach 5-8 times the rated value. The silver based alloy contacts specifically designed for electromagnetic contactors and their rapid closing action can withstand such intense current surges, which is a weak link in many electronic switch components.
When the contact is disconnected, a clear air insulation gap will be formed, and then the load side and power side will be completely cut off without leakage current risk, meeting strict power-off maintenance safety regulations.
The core electromagnetic and mechanical structure of AC Magnetic Contactor has strong tolerance to temperature, humidity, dust, and certain voltage fluctuations. In harsh industrial environments, its reliability is usually superior to complex pure electronic devices.
After millions of mechanical lifetimes, AC Magnetic Contactor wear (such as contact erosion) is predictable and gradual, making it easy to develop preventive maintenance plans and avoid sudden catastrophic failures.

How core components work together

1. Electromagnetic system (source of drive):
Coil: accepts control voltage (such as 24V AC/DC, 220V AC) and converts electrical energy into a magnetic field.
E-type static iron core and dynamic iron core: After the coil is energized, it generates magnetic force to attract the dynamic iron core. The built-in short-circuit ring is specifically designed to eliminate vibration and noise caused by AC zero crossing, ensuring quiet and smooth suction in AC environments.

2. Contact system (execution unit):
Main contact (normally open): Made of silver based materials (such as silver cadmium oxide) that are resistant to welding and have low contact resistance, capable of carrying high currents in the main circuit.
Auxiliary contact: mechanically linked with the main contact, used for controlling circuit self-locking, signal feedback or interlocking, usually with a modular design that can be flexibly combined.

3. Arc extinguishing system (safety guard):
When breaking high currents, high-temperature arcs will occur between the contacts. The AC Magnetic Contactor uses a metal grid arc extinguishing cover to cut, cool, and quickly extinguish the arc, protecting the contacts from erosion and preventing accidents caused by the arc flying out.

Application

AC Magnetic Contactor is a standard configuration control appliance for all direct online start, star delta start, and soft starter output motors.
AC Magnetic Contactor is used to control loads such as large electric heating tubes, industrial ovens, lighting groups, etc. that require frequent on/off.
The key execution unit in automatic transfer switch (ATS): responsible for physically connecting or disconnecting the power supply line during the switching of two power sources.

The main power circuit of equipment such as cranes, compressors, and die-casting machines is connected or disconnected.

SPX Household AC Modular Contactor Parameter

Frame(A)			SS-N21
KW/HP(AC-3) Reted power(AC-3) IEC60947-4		220V	5.5/7.5
		380V	11/15
Reted current(AC-3) GB14048.4		220V	22
		380V	22
Reted heating current(A)			32
Reted insutaled voltage(V)			660
Auxicary contact AC-15	Contact	Standard	2NO+2NC
	Reted current (A)	220V	1.6
		380V	0.95
Electric life			100
Machanical life			500
Outline and installation dimension
			Type	L	W	H	C1	C2	ΦD
			SS-N21	63	81	81	60	54	4.5