A contactor is the electromechanical switch that connects a motor or a load to the line, driven by a control coil so a small signal from a PLC or a pushbutton can switch a large current. A control relay is the same device sized for control circuits instead of motor loads. Contactors are consumables: contacts erode, coils burn and mechanisms wear, and when one fails the equipment it feeds stops. MT.parts keeps 160+ contactors and control relays in stock from the leading industrial brands, including models the manufacturer has discontinued.
Where these contactors are used
- Direct on line motor starters, on pumps, fans, compressors and conveyors.
- Reversing and wye-delta starters, where two or three contactors are mechanically and electrically interlocked.
- VFD and soft starter bypass circuits, so a motor can run across the line while the drive is out for repair.
- Heating and lighting circuits, switched in AC-1 duty rather than motor duty.
- Machine control panels, where control relays handle interlocks, permissives and safety circuit logic.
- HVAC and utility skids, on chillers, air handlers and pump sets that cycle many times a day.
How to choose a replacement contactor
Two contactors of the same physical size can be very different electrically. Check these before ordering:
- Part number first. The exact catalog number on the front of the contactor is the safest match. Search it in our catalog.
- AC-3 current rating at your motor voltage, in amps, plus the motor kW or HP. AC-1 ratings for resistive loads are always higher and are not interchangeable with AC-3 duty.
- Coil voltage and type, for example 24 V DC, 120 V AC 60 Hz or 240 V AC, and whether the unit uses a conventional coil or a wide-range electronic coil such as the AF series.
- Number of main poles, 3-pole for standard motor loads, 4-pole where a neutral or a fourth phase leg has to be switched.
- Built-in and add-on auxiliary contacts, how many N.O. and N.C. contacts you need for feedback and interlocks, and whether the block mounts on the front or the side.
- Frame size, mounting and terminals, 35 mm DIN rail or screw mounting, overall depth in the panel, and screw versus spring terminals, since a larger frame may not fit the existing back plate.
If you are unsure which code replaces yours, send us the nameplate data, including the coil voltage, and our team identifies the correct unit.
New, refurbished and obsolete contactors
We supply three conditions, and the condition is always stated on the product page. New units are factory-sealed. Refurbished units are inspected, repaired where needed and functionally tested before shipping, including coil pull-in and contact continuity. Obsolete and hard-to-find contactors are models the manufacturer has discontinued, which is often the only way to keep an older motor control center in service without rebuilding the bucket. Every contactor we ship carries a 12-month warranty.
Contactor brands and series we stock
- Allen-Bradley: 100-C contactors, 100-D contactors
- ABB: AF contactors, A contactors, AF/A contactors
- Siemens: IEC contactors and control relays, identified by the catalog number on the device
- Schneider Electric: IEC contactors, identified by the catalog number on the device
Frequently asked questions
What is the difference between a contactor and an overload relay?
A contactor switches the motor circuit on and off. It does not protect the motor. An overload relay, listed under motor protection, senses the running current and trips when the motor draws too much for too long. A complete starter is usually both, a contactor with an overload relay mounted underneath it.
Can I replace a discontinued contactor with a newer model?
Often yes, but frame size, terminal layout, coil voltage range and the auxiliary contact blocks may differ, which means panel rework and possibly new wiring. Replacing with the same discontinued catalog number keeps the starter exactly as documented. We stock obsolete contactors for that reason.
Do refurbished contactors come with a warranty?
Yes. New, refurbished and obsolete contactors all ship with a 12-month warranty.
How fast can I get a quote?
We reply to quote requests within 24 hours, including part identification when you only have nameplate data.
Do you ship internationally?
Yes. We ship worldwide, including to plants outside the United States.
Can't find your part number?
If the contactor you need is not listed, we source it. Send us the manufacturer, part number, coil voltage and quantity, and our team locates the unit, including discontinued models. Request a quote.