Motor protection devices and circuit breakers are what stand between a motor, a panel and a fault. Manual motor starters and motor protection circuit breakers combine short-circuit and adjustable overload protection in one device, supplementary protectors guard control circuits and small loads, switch-disconnectors provide a local isolation point, and residual current devices catch earth faults. When one of them trips and will not reset, or fails outright, the line stays down. MT.parts keeps 160+ motor protection devices and breakers in stock from the leading industrial brands, including models that are discontinued or no longer sold by the manufacturer.
Where these devices are used
- Motor control centers and starter panels, where a manual motor starter feeds each contactor and motor branch.
- Pumping stations and water plants, protecting pump motors that cycle constantly and see high inrush.
- Conveyors and material handling, with one protection device per drive section.
- OEM machine panels, where supplementary protectors on B and C curves feed control transformers, power supplies and instrumentation.
- Building and plant distribution, with RCBOs and residual current devices on branch circuits and receptacles.
- Process and packaging machinery, where a switch-disconnector at the machine gives maintenance a lockable isolation point.
How to choose a replacement protection device
Amp rating alone is not enough to match a breaker or a starter. Check these before ordering:
- Part number first. The exact code on the nameplate is the safest match. Search it in our catalog.
- Current setting range in amps. The adjustable range of a motor starter must bracket the motor full-load amps, not just contain it at one end.
- Rated voltage and number of poles, for example a 3-pole device at 480 V versus a 1-pole or 2-pole supplementary protector on a 120 or 240 V control circuit.
- Interrupting capacity, the short-circuit rating in kA at the system voltage, which has to meet or exceed the available fault current at that point in the panel.
- Trip curve and trip class, B, C or D curve on supplementary protectors and breakers, and the overload trip class on motor starters, which decides whether the device rides through motor starting.
- Mounting and accessories, DIN rail versus panel or plug-in mounting, plus auxiliary contacts, signal contacts, shunt trips, undervoltage releases, rotary handles and enclosure kits, since these are often ordered as separate codes.
If you are unsure which code replaces yours, send us the nameplate data and our team identifies the correct unit.
New, refurbished and obsolete devices
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. Obsolete and hard-to-find breakers and starters are models the manufacturer has discontinued, which is often the only way to keep an existing panel intact without rebuilding the whole feeder section. Every device we ship carries a 12-month warranty.
Brands and series we stock
- Allen-Bradley: 140G circuit breakers, supplementary protectors (2-pole and 3-pole, B and C curve)
- Schneider Electric: motor circuit breakers, overload relays and switch-disconnectors
- ABB: Tmax breakers, MS116, MS132 and MS165 manual motor starters, OT switch-disconnectors and accessories, DS200 RCBOs, F200 residual current devices, CM-MPS monitoring relays
- Siemens: motor starter protectors, overload relays and circuit breaker accessories
Frequently asked questions
What is the difference between a motor protection device and a contactor?
A contactor is the switching element: it opens and closes the motor circuit on command from the control logic, over and over. A motor protection device does not switch the motor in normal operation. It watches for overload and short-circuit conditions and disconnects the circuit when they occur. In a classic starter the two work together: the protection device upstream, the contactor doing the daily switching.
Can I replace a discontinued breaker with a newer model?
Sometimes, but the frame size, terminal arrangement, DIN-rail footprint and accessory codes often change, so the replacement may not fit the existing busbars or the panel cutout. Replacing with the same discontinued part number keeps the panel exactly as built. We stock obsolete breakers and starters for that reason.
Do refurbished breakers come with a warranty?
Yes. New, refurbished and obsolete devices 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 breaker or starter you need is not listed, we source it. Send us the manufacturer, part number and quantity, and our team locates the unit, including discontinued models. Request a quote.
