Blog > Automation > 140M to 140MT Motor Protection Circuit Breakers

140M to 140MT Motor Protection Circuit Breakers

12/14/21  |  Will Cole, Rexel Technical Consultant

Going From 140M to 140MT

What is a 140M? These are Motor Protection Circuit Breakers (MPCB) from Rockwell Automation. They are a device designed to provide short circuit protection, a disconnect for a motor circuit, and overload protection for the motor—all in one device. 

Also known as group motor, Bulletin 140M is common in multiple motor applications. Think branch circuit. Many applications can use multiple motors of the same capacity, operating in parallel at the same speed. In such applications, you can use one variable-frequency drive (VFD) to control multiple motors, with a 140M MPCB on each motor. This illustration shows a common example of 140M MPCB used in a group motor application.


The 140 families have been around for years, and we love it. So why is it going away? Two key reasons. One, improved performance. And two, portfolio readiness. Improved performance means that the new 140MT family will offer control engineers higher short circuit ratings, expanded current ranges, and lower heat loss. Portfolio readiness means the new 140MT family allows for expanded global certifications. 

The quick transition to 140MT represents the lowest risk to projects in 2022. The key takeaway from the video above is to review this transition information and modify your automation specification as needed.

Similarities and Differences

The two families actually look quite similar. These images show an old 140M side by side with a new 140MT.

The new 140MT has a more modern look, a slightly different knob, a QR code, and other minor differences. In the bigger picture of product migrations, this 140M to 140MT is relatively straightforward. All the old 140M MPCB have a direct cross to a new 140MT part number. In most cases, they will stay in the same frame size. There are cases where the old item will be a C and the new is a D frame size, for example. The C and D frames sizes are both a 45mm width, as far as the footprint. 

Migration Timeline

So, what is the timeline? Rockwell Automation has announced that as of March 2022, the Bulletin 140M motor protection circuit breakers will be discontinued and no longer available for sale. Right now, we are actively reaching out to our customers to help them proactively migrate to Bulletin 140MT motor protection circuit breakers. Bulletin 140M MPCB are going away and being replaced with 140MT MPCB. Depending on your role, that may mean getting with a Controls Engineer to update drawings. It may mean working with purchasing and the supply chain to start superseding part numbers in our systems. It may mean reaching out to your customer base to alert them of the change for purposes of spare parts. 

Technical Details

When you get into the specific technical details, we have documentation showing the crosses and frame sizes, and so forth. That full documentation can be found here and here. I do want to give a quick rundown of the new 140MT line, the technical specs so to speak. 

  • - The C frame goes up to 32A, the D Frame up to 40A
  • - Short circuit protection 65kA @ 480V / 100kA @ 400V
  • - Trip Class 10
  • - Accessories include auxiliary contacts, under-voltage release, and shunt trips. For both the old 140M and the new 140MT, aux contacts can be either front mount or side mount.

One valuable detail. The 140M-F frame size is actually not going away just yet, it remains active and the related accessories for the 140M-F unit will also remain active at this time.


Last topic: let’s talk about testing. The video above was shot in October of 2021 and as of right now, we want to share some key dates and details regarding testing plan for short circuit current rating. We are dialing in on testing the 140MT MPCB with PowerFlex® products. We anticipate this testing to be complete in January of 2022. Your local Automation Specialist can keep you informed of this, as it is quite technical in nature.

In the coming weeks, you can expect that some 140M items (the old ones, going obsolete) will show lower stock levels. There will be controls in place to minimize hoarding. There will be no blocks or holds on the new 140MT items, and they should be available to order now. Going forward, those old 140M items will become more and more difficult to find. Most of the 140M MPCB are direct crosses, drop in, offering very easy, straightforward updates. It’s a good time to start updating drawings, bills of material, and notes within your system. Right now is also a good time for OEMs and system integrators to proactively communicate the acceptance of 140MT MPCB to your user base.

Key Takeaways

The key takeaway from this video is awareness of this 140M to 140MT migration. If you are a user of the old 140M family, you should start work to modify your automation specification to the new 140MT family as acceptable and preferred. That means actually getting in the drawings and the bills of material and updating part numbers. The soon-to-be-old 140M family is very common in automation control panels. We use them every day. Lots of proactive changes to be made. In closing, the quick transition to the new 140MT family represents the lowest risk to projects in 2022. We're here to help make that a reality. Thank you for taking the time to watch this video, and remember—where there’s a Will, there’s a way.