ONESTO
New User
- Location
- Los Angeles
- Occupation
- electrical engineer
Electronic vs Thermal Magnetic Molded Case Circuit Breaker，What are the differences in core functionality and performance
Electronic vs Thermal Magnetic Molded Case Circuit Breaker
- Thread starter ONESTO
- Start date
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
Electronic generally are more accurate in measuring current in temperature extremes and measuring true RMS current (including harmonics), where thermal magnetic are biased by temperatures.
Electronic will often have options for adjustable LSIG characteristics, where thermal magnetic may have inst adjustments.
Electronic often will allow for trip unit / rating plug replacements to adjust long time pickup settings.
Electronic will often have options for adjustable LSIG characteristics, where thermal magnetic may have inst adjustments.
Electronic often will allow for trip unit / rating plug replacements to adjust long time pickup settings.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Ron covered the basics.
At 400A, and larger, electronic trip are typical not much of a cost adder, depending on which functions are chosen. Electronic have become very common if not the norm over the past 15 years.
Smaller electronic breakers tend to be much more expensive than their thermal-magnetic cousins, and so are not very common.
Below 100A electronics don't fit well into the small housings, so you end up paying for a big breaker with a small trip element.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
In N. America, thermal mag circuit breakers must have a fixed thermal trip setting. The exception is that you can use adjustable thermal trips on “Motor Protection Circuit Breakers” (MPCBs) which means only in motor circuits. Elsewhere in the world, adjustable thermal trips are more widely used for everything.
Circuit breakers with electronic trips however are allowed (here) to have programmable long term trips, the equivalent of thermal trips. That provides more flexibility and in many cases that can have benefits. As mentioned they can also have separate programming for shorty time trips and instantaneous trips, as well as built in Ground Fault trips (Equipment, not personnel), which is especially useful at 1,000A and above where it might be required. A newer feature now is also “Maintenance Mode” (MM Trip) which allows for a temporary reduction of the trip thresholds to help reduce arc flash incident energy while someone is working on gear. That can be very useful.
Circuit breakers with electronic trips however are allowed (here) to have programmable long term trips, the equivalent of thermal trips. That provides more flexibility and in many cases that can have benefits. As mentioned they can also have separate programming for shorty time trips and instantaneous trips, as well as built in Ground Fault trips (Equipment, not personnel), which is especially useful at 1,000A and above where it might be required. A newer feature now is also “Maintenance Mode” (MM Trip) which allows for a temporary reduction of the trip thresholds to help reduce arc flash incident energy while someone is working on gear. That can be very useful.