Schneider Contactor FAQ: LC1D09BD, VFDs, and the Difference Between Contactor and Relay

I've spent seven years on the ordering side of an industrial electrical supply company, mostly with Schneider Electric LC1D contactors—LC1D09, LC1D12, LC1D18, LC1D25, and LC1D32. I've made maybe $12,000 worth of mistakes. Maybe $12,300 if you count the shipping. This FAQ is the list I hand to new team members before they place their first contactor order. It's not a textbook. It's the stuff I learned by paying for it.

These are answers to the questions I get asked most—and one question I wish someone had asked me before it cost us a weekend.

What does “Schneider contactor” mean? And what is an LC1D09BD contactor?

“Schneider contactor” is the shorthand for the power contactors made by Schneider Electric. In the LC1D line—the TeSys D series—the LC1D prefix means three main poles and power switching. The Schneider Electric LC1D09BD contactor is one of the most common I order: a 9 A AC-3 contactor, 24 V DC coil, 3P, with one NO and one NC auxiliary contact. The 9 A rating is under IEC AC-3 conditions, so always check the full catalog value for your application.

The last letters matter more than people think. In 2018, I ordered 40 LC1D contactors and ended up with AC coils instead of DC coils. The order looked right in the spreadsheet. The machine builder wired everything and nothing clicked in. That mistake cost close to $1,100—no, $1,180 with the expedite fee. I still kick myself for not checking the coil code twice.

What’s the difference between a contactor and a relay?

Technically, a contactor is a heavy-duty relay. In practice, they’re designed for different sides of a control panel.

A relay is usually for control circuits: small contacts, lower current, PLC outputs, pilot lights, interlocks. A contactor is for power circuits: motors, heaters, lighting banks. It has deeper contact gaps, arc suppression, and ratings for making and breaking load current many times.

IEC 60947-4-1 defines contactor utilization categories. An AC-3 rating covers switching of squirrel-cage motors—start and stop under normal running conditions. An AC-4 rating covers inching and plugging, which is much harder on the contacts.

If your load is an AC motor, you need a contactor with a utilization category, not just a relay with a current rating that looks close. I worked on a project where a 25 A power relay was used on a 5 kW motor because the OEM wanted to save space. The contacts welded within six months. It wasn’t VFD controlled; it was direct-online. Different setup, same lesson: use the part that’s rated for the job.

Can I use a Schneider LC1D contactor with a VFD controller for AC motor?

Yes, but the contactor’s role changes.

A VFD controller for AC motor speed control handles starting, stopping, acceleration, and deceleration. The contactor usually belongs on the input side of the VFD, between the supply and the drive, for isolation and maintenance. Do not use it as the start/stop switch for the drive while the VFD is running. That can stress the input rectifier, cause overvoltage faults, and shorten drive life. Use the drive’s control terminals for normal operation. If you need a bypass, design it with proper interlocks—don’t improvise on site.

I once had a customer who put an LC1D18 in front of his VFD and then used it to disconnect the drive every time the motor stopped. The drive faulted constantly. The real issue wasn’t the contactor. It was the control logic. We stopped using the contactor as a stop switch and the drive stopped complaining.

One more VFD point: when the drive manual asks for a specific upstream fuse or circuit breaker, don’t swap in a contactor “upgraded” to a bigger frame and ignore the coordination. The contactor is not there to protect the drive. It’s there to isolate it.

Do I still need a contactor for a VFD single phase to three phase?

Yes—on the input side.

A VFD single phase to three phase application takes single-phase AC input and creates three-phase output for a standard three-phase AC motor. These VFDs are common for smaller motors, often up to around 3 kW or 4 HP in typical product lines, but check the manufacturer’s spec for the exact model. You still need a disconnecting means. A contactor upstream of the VFD gives you safe isolation for maintenance and servicing.

Downstream, between the VFD and the motor, you normally don’t add a standard contactor if it’s going to switch while the drive is running. The VFD is the controller. That’s the whole point.

The phrase people search for is “VFD single phase to three phase,” not “rotary phase converter.” The VFD does the phase conversion, not the contactor.

Schneider LC1D09 vs LC1D12 vs LC1D18—how do I pick the right one?

Look at the motor’s full-load current at your operating voltage, then check the Schneider Electric TeSys D catalog for the right LC1D contactor. The number in the model name is a clue: LC1D09 is rated 9 A in AC-3 under the manufacturer’s standard reference conditions, LC1D12 is 12 A, LC1D18 is 18 A, LC1D25 is 25 A, LC1D32 is 32 A. Those numbers follow IEC 60947-4-1 test conditions, so the corresponding motor kW changes with line voltage and temperature.

I keep a bookmark for the Schneider catalog page with the AC-3 tables. I use it even when I’m sure. Because I’ve been burned by “sure.”

One more thing: don’t oversize the contactor just to feel safe without checking the control transformer. A bigger coil can draw more current than your 24 V control supply can deliver. I found that out the expensive way in 2022.

Since then, my checklist has four items: line voltage, control voltage, utilization category, and auxiliary contacts. If all four aren’t on the PO, I stop and ask.

Why are Schneider LC1D contactors pricier than no-name options?

Because the purchase price is not the total cost.

In 2022, I bought a batch of low-cost contactors for a panel shop to save about $320 on the order. My gut said the coil markings looked inconsistent, but the spreadsheet said $320 savings. I went ahead anyway. The panel builder installed six before someone noticed the markings didn’t match. The labor to tear the panel apart, reinstall the correct units, and deal with the two-day delay came to roughly $1,800. So the $320 savings turned into a $1,500 problem before anyone mentioned the customer’s lost production.

I’m not saying every no-name contactor is bad. I’m saying the total cost equation has hidden terms: install labor, downtime, troubleshooting, callback visits, and the chance it fails in front of a customer. TCO beats unit price every time I do the math.

And if a “Schneider” LC1D09BD contactor is priced far below every authorized channel, treat it as counterfeit until proven otherwise. I opened a box like that once. The coil code was a sticker over a different coil code. The real part doesn’t show up that way.

What’s the one LC1D mistake I wish every buyer asked about earlier?

Coil voltage. Nobody asks about it until the panel is already wired.

In 2021, a machine builder ordered “LC1D09B7” when the print specified LC1D09BD. Both are 9 A contactors. Both have one NO and one NC. But the B7 has a 24 V AC coil and the BD has a 24 V DC coil. The panel was DC. The installers finished, and the contactor never pulled in. It took a day and a half—maybe closer to two days—to trace a problem that was visible in the catalog number all along.

So write the full catalog number and the coil voltage on every PO. Then check it before shipment, not after the electrician is on site. The difference between a Schneider contactor that works and one that doesn’t is often the last two letters.