ABB MS325-16 circuit breaker replacement/alternative

[eagle1109]

Hi,

We have electronics laboratory bench with ABB MS325-16 circuit breakers installed.

Now there are couple ones that have knob broken. I tried to fix it, but when I opened the CB, the part connected with knob movement is broken and the department's head asked me to search for replacements and I told him that they are pretty expensive.

And also opening the product page at ABB site, it's listed as motor starter, where they are installed in the laboratory bench mains so I assume that it should not be necessarily used only with motors, they are basically CBs and should perform as any CB. Am I right here ?

So I guess, I can replace them with any similar circuit breakers from aliexpress and should work.

The current rating doesn't matter anyway, because the bench has devices; like, DC/AC power supplies, function generators ... etc. The most the time the bench isn't fully loaded so any CB within 10A should work.

Any suggestions or tips for me in this case ? Should I recommend cheaper options for the department or not ?

 

[c_mitra]

So I guess, I can replace them with any similar circuit breakers from aliexpress and should work.

Right, you should be safe.

But CB for motors are really not needed for a lab use. You can safely (and a better replacement) replace with one rated for lights (and they will be happy with electronic instruments).

 

[betwixt]

Motor start switches are rated for high initial surge currents, if you are not using large motors, any circuit breaker can be used as a replacement. Do note that it is a three-phase switch so if you have such a supply, you should replace it with a linked three phase breaker. This is one that has three individual switches but only one lever so they operate simultaneously.
Like this one: https://www.screwfix.com/p/wylex-32a-tp-type-b-3-phase-mcb/2266p
but 16A rated.

Brian.

 

[FvM]

If the lab bench involves an isolation transformer, a motor circuit breaker might be used due to it's precise overcurrent trip characteristic.

 

[eagle1109]

Hi,

Thank you all for the replies.

Let me put information and follow up points about the bench setup:

Right, you should be safe.

But CB for motors are really not needed for a lab use. You can safely (and a better replacement) replace with one rated for lights (and they will be happy with electronic instruments).

Yep pretty much thought so.

Motor start switches are rated for high initial surge currents, if you are not using large motors, any circuit breaker can be used as a replacement. Do note that it is a three-phase switch so if you have such a supply, you should replace it with a linked three phase breaker. This is one that has three individual switches but only one lever so they operate simultaneously.
Like this one: https://www.screwfix.com/p/wylex-32a-tp-type-b-3-phase-mcb/2266p
but 16A rated.

Brian.

Yes, it's 3-ph switch but I think the wires are L, N and GND. I didn't find or notice any 3-ph devices used in the labs. Most of labs equipment are: computers, power supplies, PLC kits, other electronics kits ... etc. I think if there are 3-ph stuff would be in electrical labs but I work in electronics department.

If the lab bench involves an isolation transformer, a motor circuit breaker might be used due to it's precise overcurrent trip characteristic.

There's no isolation transformer, it's directly connected from the 220V mains. For this particular lab, there are control buttons panel in the trainer's table to control the power of each bench.


These are more photos:

Even so, these fault CBs got broken because someone pulled that knob more than enough I believe. So I would like if the department wanted to put something other than the original ABB as betwixt suggested the lever ones.