Contactors and Motor Starters
In most industrial systems, reliability is built from simple things.
Before inverters, PLCs, or SCADA come into play, motors still need to be switched, protected, and isolated correctly.
That job is handled by motor control and protection devices — the core elements of any control cabinet.
Mitsubishi Electric motor control components are designed for predictable operation, clear coordination between devices, and long service life in real industrial conditions — where equipment runs every day, not only during commissioning.
Why These Devices Matter
Failures at the motor control level are among the most common causes of unplanned downtime.
Incorrect protection settings, undersized contactors, or missing coordination between devices often lead to motor burnout, nuisance trips, or unsafe operation.
Properly selected control and protection devices help ensure:
- safe and controlled motor starting and stopping
- protection against overload, short circuit, and phase loss
- stable operation under normal and abnormal conditions
- clear fault indication for faster troubleshooting
- longer motor and equipment service life
Typical Device Groups
Motor Starters
Motor starters combine switching and protection functions into a single unit.
They are commonly used for direct-on-line (DOL) starting and basic motor control, providing overload protection and preventing motor burnout during abnormal operation.
Contactors
Contactors are electromagnetic switching devices used to control load current.
They are designed for frequent switching and are widely used for motors, heaters, and other industrial loads.
Solid State Contactors
Solid state contactors use semiconductor devices instead of mechanical contacts.
They provide silent, wear-free switching and are well suited for applications with high switching frequency or where mechanical contact wear is a concern.
Definite Purpose Contactors
Definite purpose contactors are optimized for specific loads and operating conditions.
They are typically used where switching is infrequent and load characteristics are well defined, offering a cost-effective solution for dedicated applications.
Motor Protection Relays
Motor protection relays monitor electrical and thermal conditions to protect motors from overload, phase imbalance, and other abnormal states.
They help prevent motor burnout and provide clear fault signaling for maintenance teams.
Motor Circuit Breakers
Motor circuit breakers integrate short-circuit protection and thermal overload protection into a single device.
They are often used as a compact alternative to a combination of circuit breaker and thermal overload relay.
Relays
Control relays are used to command and transmit signals within control circuits.
They provide electrical isolation, interlocking, and logic functions essential for safe and reliable automation systems.
Where These Devices Are Used
- motor control centers (MCCs)
- machine control cabinets
- pump, fan, and compressor systems
- conveyor and material handling equipment
- heating, ventilation, and auxiliary systems
How Selection Usually Starts
Choosing the right combination of motor control and protection devices is rarely about a single component.
In practice, selection starts with understanding the motor and the operating conditions:
- motor rated power and current
- starting method and duty cycle
- short-circuit level at the installation point
- required level of protection and diagnostics
- coordination with upstream breakers and downstream loads
Correct coordination between devices is critical — especially in systems where downtime or equipment damage is costly.
Engineering Support
Even “simple” control components benefit from an engineering approach.
Incorrect settings or mismatched devices often cause more problems than complex automation systems.
Our engineers can help with:
- device selection and coordination
- motor protection settings and verification
- cabinet architecture and standardization
- modernization of existing control panels
If you want to start efficiently, provide motor data, operating conditions, and a basic single-line diagram — and we’ll help define a reliable and practical solution.
