Eaton LGH breaker trip unit

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OCPD

Member
Location
Tempe, AZ
Hello,
Why does the Eaton breaker have tsd = Inst (J K L), 120 ms (M N O), 300 ms (P Q R). What do these letters mean and there are three notches on the breaker as well. I am pretty sure it has significance not sure what. Is it something to do with tolerance?
 

Julius Right

Senior Member
Occupation
Electrical Engineer Power Station Physical Design Retired
In my opinion, the circuit breaker Eaton LSIG- for instance- is provided with two short-delay possibility: one for short-circuit between phases [tsd] and one for phase to ground [tg].The letters on the selector indicate the delay combination of these.
Let's say for tsd=inst. [instantaneous] between phases and tg=300 ms delay for ground fault the L position has to be selected. See:
file:///C:/Users/user/Downloads/TD012019EN.pdf
 

OCPD

Member
Location
Tempe, AZ
In my opinion, the circuit breaker Eaton LSIG- for instance- is provided with two short-delay possibility: one for short-circuit between phases [tsd] and one for phase to ground [tg].The letters on the selector indicate the delay combination of these.
Let's say for tsd=inst. [instantaneous] between phases and tg=300 ms delay for ground fault the L position has to be selected. See:
file:///C:/Users/user/Downloads/TD012019EN.pdf


Thank you.
 

Ingenieur

Senior Member
Location
Earth
In my opinion, the circuit breaker Eaton LSIG- for instance- is provided with two short-delay possibility: one for short-circuit between phases [tsd] and one for phase to ground [tg].The letters on the selector indicate the delay combination of these.
Let's say for tsd=inst. [instantaneous] between phases and tg=300 ms delay for ground fault the L position has to be selected. See:
file:///C:/Users/user/Downloads/TD012019EN.pdf

Exactly :thumbsup:
 
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