Selecting the wrong magnetic contactor — undersized or over-specified — wastes cost and causes premature failures in motor control panels. OHI Tech is the official Korean partner of TECO Electric & Machinery (TWSE: 1504) and supplies the full TECO power distribution lineup: AC contactors, overload relays, MCB, MCCB, and ACB. This guide covers TECO contactor series comparison, MCCB vs ACB vs MCB selection criteria, and real-world panel supply cases.
What Is a Magnetic Contactor? — Role and Applications
A magnetic contactor uses an electromagnet (coil) to remotely switch high-current circuits, making it the core component for motor start/stop control.
When control voltage (AC 24V–440V) is applied to the coil, contacts close. When voltage is removed, a spring returns contacts to open position. PLC, timer, or pushbutton remote control requires no manual operation.
Main applications:
- Pump, conveyor, and machine tool motor start/stop
- Star-delta starting circuits (reducing inrush current for large motors)
- HVAC fan, chiller, and heater automatic control
- Load switching in power distribution panels
TECO CN / CU / TMC Series — Selection by Load Current
| Series | Current Range | Key Feature | Main Application |
|---|---|---|---|
| CN Series | 6A – 95A | Compact, standard control voltage AC 24–440V | Small motors, general loads |
| CU Series | 9A – 800A | Medium/large capacity, high durability | Large motors, heavy industry |
| TMC Series | 6A – 800A | Integrated motor starter format, compact | Motor starters, panel mounting |
Why Overload Relay (RHU/EOR) Must Pair with the Contactor
A contactor alone cannot protect against motor overload. Overload relays (RHU/EOR) detect overcurrent and break the contactor coil circuit, preventing motor burnout.
| Type | Model | Range | Feature |
|---|---|---|---|
| Thermal | RHU Series | 0.1A – 95A | Bimetal type, low cost, general use |
| Electronic | EOR Series | 0.5A – 336A | Digital setting, includes phase-loss protection |
MCCB vs ACB vs MCB — Which Circuit Breaker Do You Need?
Unlike contactors (switching control), circuit breakers protect against short-circuit and overcurrent by automatically tripping.
| Type | Model | Current Range | Application |
|---|---|---|---|
| MCB (NFB) | TMS / BM / BR | 0.1A – 125A | Branch circuit protection, small equipment |
| MCCB | TCB / TAX | 16A – 800A | Feeder protection, general factory distribution |
| ACB | TAW / BAW / TBW | 630A – 6,300A | Main breaker, large-capacity incoming panels |
- Rated current ≥ maximum load current × 1.25
- Breaking capacity (kA) ≥ prospective short-circuit current at installation point
- TCB series supports plug-in replacement for easier maintenance
OHI Tech TECO Power Distribution Supply Cases
OHI Tech supplied 87 TECO CU series contactors (45A–185A), EOR electronic overload relays, and 32 TCB MCCB units for a domestic chemical plant switchboard renewal project. Lead time was 3 weeks from order. All products carry CSA and CE certification, meeting export equipment requirements.
For a mid-sized food manufacturer new production line, 18 TMC motor starter units were supplied, reducing panel interior space by 40% compared to individual component assembly.
References
Frequently Asked Questions
Q1. What is the difference between magnetic contactor, 전자개폐기, and 마그네트? A. These are different names for the same product. The official term is magnetic contactor (MC); in Korean industrial sites it is also called 마그네트 or 전자개폐기. All TECO CN/CU/TMC products follow the same technical standards.
Q2. What certifications does TECO contactor hold for export? A. TECO contactors carry CSA (North America), UL (USA), CE (Europe), CCC (China), and RoHS. For domestic KS compliance confirmation, contact OHI Tech.
Q3. Why install both a magnetic contactor and MCCB in the same panel? A. They serve different functions. The contactor handles routine switching (start/stop control); the MCCB provides automatic protection against short-circuit and overcurrent. Using both is standard per IEC and KEC motor protection requirements.
For contactor selection, MCCB/ACB capacity calculation, or TECO power distribution supply inquiries, contact OHI Tech. Share your panel drawing or site conditions and we will recommend the right series and rating. jino.kim@ohitech.co.kr
→ [View full TECO contactor, MCCB, and ACB lineup](/products/power-distribution)