Home › Electrical Engineering Forum › General Discussion › How long do electronic trip units for low voltage power circuit breaker last? › Re: How long do electronic trip units for low voltage power circuit breaker last?
I would like to get a feedback from
your community regarding the reliability of electronic trip unit controlling low
voltage power circuit breaker:
Electronic trip unit are not new on
Air Circuit Breaker but I have the feeling that new products (see for instance
Larsen Tubro UPOWER + OMEGA) include more and more new technologies like
wireless communication, touch screen, metering, communication.
I wonder if such electronic product
can last as long as electro-mechanical part of the breaker.
Does anybody have reliability figures
(MTTF) of the trip unit itself ?
Do you know if some manufacturers
propose trip unit replacement during maintenance operation?
I went through the documentation of
* Larsen & Tubro UPOWER OMEGA + Matrix
Protection & Control Unit
* Schneider Electric Masterpact +
* ABB Emax + PR121/122/123
* GE EntelliGuard + EntelliGuard Trip unit
* EATON Magnum + Digitrip
* Siemens Sentron 3WL + ETU
and I don't find a lot of information on
reliability and life expectancy of trip units. I think simplest trip unit is more reliable and easier to maintain, and
usage of external devices for metering or advanced protection is still
possible. But I don't have a long field
experience of such advanced trip units.
I used a lot of CB either ” MCCB ” or ” ACB ” equiped with Electronic Protection Units, and I can say that their reability and advantages are good, but I have some comments :
– We should be carfull when we do the adjustment.
– I hade, in some time, a connection's problem between the Protection Unit and the the connection base in the CB ( specialy in MCCB ).
– A few CB and after a long time of istallation, tripped at a value smaller than adjustment one ( specialy in MCCB ).
– The big problem that we can't replace these units, because that needs an authorization from the manufacters, and also the electric connection between the Protection Unit and the CB should absolutly be tested, if not, we aren't sure that the trip order from the Protection Unit will trip the CB.