Delixi CDC6i Series CDC6i-6511 65A AC Contactor 1NO+1NC

KOEED · Motor Control & Contactors · AC Contactors · In stock

What Is the Delixi CDC6i-6511 AC Contactor?

The Delixi CDC6i-6511 is a 3-pole AC magnetic contactor rated for 65 amps (AC-3 utilization category, which covers squirrel-cage motor starting and running) with a coil voltage selectable from 24V, 36V, 110V, 220V, or 380V AC. The "6511" designation breaks down as: 65 for the rated current in amperes, and 11 indicating one normally-open (NO) and one normally-closed (NC) auxiliary contact. The CDC6i series is Delixi's current-production industrial contactor line, designed for switching motors, resistive heating loads, lighting banks, and power distribution circuits in factories, HVAC systems, pumping stations, and commercial building electrical rooms. The 1NO+1NC auxiliary contact configuration allows the contactor to provide status feedback to a PLC input module, hold itself in a latching circuit (with the NO contact in parallel with the start pushbutton), or energize a run indicator lamp.

In short: If you are building or repairing a motor starter, heater control panel, or lighting contactor that needs a 65A 3-pole AC contactor with one NO and one NC auxiliary contact, the Delixi CDC6i-6511 is the correct part — select your coil voltage from the available options. In stock at koeed.com.

AC-1 vs. AC-3: Understanding Contact Ratings

The same contactor has different current ratings depending on the type of load it is switching. This is critical for correct selection:

• AC-3 rating (65A): This is the rating for starting and stopping squirrel-cage induction motors. It accounts for the 6-8x inrush current the contacts must withstand during motor starting. A contactor rated AC-3 at 65A can switch a motor drawing roughly 30-37 kW (40-50 HP) at 400V 3-phase, depending on motor efficiency and power factor.
• AC-1 rating (higher than AC-3): For resistive loads like heating elements or mildly inductive loads like distribution feeders, the same contactor can handle more current — typically 80-100A — because there is no motor inrush current to erode the contacts. If you are switching a resistive heater bank at 80A, this contactor is suitable despite the "65A" label.
• AC-5a and AC-5b: These are for discharge lamp and incandescent lamp switching respectively, which have their own unique inrush characteristics. Do not use an AC-3 contactor for large lighting loads without checking the specific lighting rating — the high inrush current of cold filaments can weld the contacts that were designed for motor starting inrush.
• Auxiliary contacts (1NO+1NC): The auxiliary contacts are rated for control-level current (typically 10A AC-15 or 2.5A DC-13). They are not designed to switch motor power — only PLC inputs, contactor coils, indicator lamps, and similar low-power control circuits.

Key Specifications

Always verify the coil voltage printed on the contactor before wiring. A 24V coil connected to 220V will burn out instantly. Conversely, a 220V coil fed with 24V will not pull in at all — the contacts will remain open or chatter, quickly destroying the contact surfaces.

Frequently Asked Questions

"How do I wire this contactor for a start/stop motor control circuit?"

For a basic 3-wire start/stop control: connect your stop pushbutton (NC) in series with the contactor coil circuit. Connect your start pushbutton (NO) in parallel with one of the contactor's NO auxiliary contacts — this is the "seal-in" or "holding" contact. When you press Start, the coil energizes, the main contacts close to run the motor, and the NO auxiliary contact closes to maintain coil power after you release the Start button. Pressing Stop breaks the coil circuit regardless of the auxiliary contact state. The NC auxiliary contact can be wired to a PLC input or an indicator lamp to show "contactor off" status. Always include a properly sized overload relay in series with the motor load — the contactor provides switching but not motor overload protection on its own.

"I need to switch a single-phase 240V load, not a 3-phase motor. Can I use this 3-pole contactor?"

Yes. A 3-pole contactor works for single-phase loads — simply use two of the three poles (one for each hot leg of a 240V single-phase circuit) and leave the third pole unused. Alternatively, wire all three poles in series (line through pole 1 to pole 2 to pole 3 to load) to increase the total contact gap and improve arc quenching, which is common practice for DC switching where arc extinction is more challenging. For high-voltage DC switching with an AC-rated contactor, always de-rate the current significantly and consult the manufacturer's DC switching curves.

"The contactor hums loudly when energized. Is it defective?"

A certain amount of 50/60 Hz hum from an AC contactor is normal — it comes from the alternating magnetic field in the coil core causing the laminated steel armature to vibrate slightly at twice the line frequency (100 Hz or 120 Hz). However, excessive hum indicates a problem: (1) Dirt, rust, or paint on the pole faces of the armature — the magnetic mating surfaces must be clean, flat, and free of debris. (2) A broken shading coil — AC contactors have a shorted copper turn embedded in the pole face that provides a phase-shifted magnetic field to hold the armature closed during the AC zero-crossing. If the shading coil is cracked or missing, the contactor will buzz loudly and may chatter. (3) Coil voltage too low — if the actual supply voltage is more than 10% below the coil's rated voltage, the magnetic force is insufficient to pull the armature fully closed against the spring.

koeed.com supplies industrial contactors, motor starters, overload relays, and control panel components from Delixi, Schneider Electric, Siemens, and other major manufacturers. For panel-building projects requiring coordinated contactor/overload/circuit-breaker combinations, send your motor nameplate data and voltage to Moritta@KOEED.COM for a complete BOM quote.