• How contactors differ from relays
• Their inner workings and key components
• The 5 significant types and where they’re used
• Pro tips for selection and maintenance
What Makes Contactors Unique?
A contactor is an electromechanical switch designed for heavy-duty current switching (typically 10A–1000A+). Unlike household light switches, contactors are used.
• An electromagnetic coil to remotely control the circuit
• Arcing suppression (via vacuum, gas, or extraordinary chambers) for safe high-load disconnection
• Durable contacts (often silver alloy) to withstand thousands of operations
How Contactors Work: The Science Behind the Switch
- Activation: Voltage
applied to the coil creates a magnetic field.
- Engagement: The
field pulls the movable contacts toward stationary ones, closing the
circuit.
- Deactivation: When
power cuts, springs return contacts to their default (open) position.
Key Advantage: This design allows low-power control
circuits (e.g., a thermostat) to safely operate high-power systems (e.g., HVAC
compressors).
5 Types of Contactors and Their Jobs
|
Type |
Best For |
Unique Feature |
|
Electromagnetic |
Motors, pumps |
Most common,
cost-effective |
|
Solid-State (SSR) |
Frequent switching
(e.g., LED lighting) |
No moving parts;
silent operation |
|
Reversing |
Conveyors, elevators |
Two contactors for
motor direction change |
|
Vacuum/Gas-Filled |
High-voltage grids |
Prevents arcing in
demanding environments |
|
Manual |
Emergency overrides |
No coil;
human-operated |
Where You’ll Find Contactors in Action
- Industrial: Assembly
line motors, CNC machines
- HVAC: Compressor
control in chillers and heat pumps
- Renewables: Solar inverters, wind turbine pitch systems
