TECO AC Contactor CU-23 220VAC

TECO CU-23 AC Contactor (220VAC Coil)

The TECO CU-23 is a highly reliable, heavy-duty AC contactor engineered for demanding industrial motor control applications. Operating with a standard 220V AC coil, it is designed to frequently switch electrical power circuits, making it a critical component in motor starters, automation panels, and HVAC systems.

Built in compliance with international IEC standards, the CU series ensures optimal arc quenching and minimal contact bounce. The "23" class rating makes it exceptionally suited for controlling 3-phase squirrel-cage motors (AC-3 utilization category) up to 11 kW (15 HP) at 380V-415V, providing a robust solution for factory automation infrastructure.

Detailed Technical Specifications

Industrial Application & Reliability

The AC-3 utilization category implies this contactor is built to withstand the massive inrush currents generated when starting a squirrel-cage induction motor (typically 5 to 7 times the full load running current), and safely breaking the current while the motor is running.

• Motor Control Centers (MCC): Frequently used in combination with thermal overload relays to form direct-on-line (DOL) motor starters for conveyors, pumps, and fans.
• HVAC Systems: Engaging and disengaging commercial air conditioning compressors and heavy-duty ventilation blowers.
• Electrical Isolation: Capable of providing safe electrical segregation in automation cabinets due to its robust silver-alloy contact design, minimizing contact welding risks under heavy loads.

Troubleshooting & Maintenance FAQ

1. The contactor emits a loud buzzing or humming noise when engaged.
A loud hum is not normal for a healthy AC contactor. This is almost always caused by one of two issues: First, check your control voltage. If the voltage supplied to the 220V coil drops significantly (e.g., below 180V) during startup, the magnetic pull is too weak to hold the armature tightly closed against the spring. Second, dust, rust, or debris may have accumulated on the faces of the magnetic iron core inside the contactor, preventing a flush seal. Blowing the core clean with compressed air usually resolves this.

2. The motor won't stop running even after the control power is turned off.
This is a dangerous condition known as "contact welding." It occurs when an excessive overcurrent event (like a short circuit) or severe motor overload creates a massive arc that physically melts the silver alloy contacts together. If the contactor remains closed with no power applied to the A1/A2 coil terminals, the contacts are welded. The CU-23 must be replaced immediately, and you must investigate the root cause of the overcurrent.

3. Can I use a 220VAC coil contactor on a 24VDC control circuit?
No. Applying 24V DC to a 220V AC coil will not generate enough magnetic flux to actuate the contacts. Conversely, applying AC voltage to a DC coil will cause it to burn out instantly due to the lack of inductive reactance. The coil voltage must exactly match your control circuit panel voltage.