SIEMENS relay has three "ANSI 50" settings...?

[Mongao]

Hi friends,


I need to understand the SIEMENS relay 7SJ640, it has 3 "ANSI 50" functions called 50-1, 50-2 and 50-3.


Please, how do these functions work together ? Let's say for example that I want the relay to trip the breaker instantaneously if the current reach 1200 A, how should these 3 functions be set ?


Thanks a lot,


Mongao

 

[Jraef]

The dash number are just meaning there are more than one "50" trip setting. In the case of Siemens Siprotect relays, they allw you to set 3 different settings independently for each phase.

 

[Mongao]

The dash number are just meaning there are more than one "50" trip setting. In the case of Siemens Siprotect relays, they allw you to set 3 different settings independently for each phase.

Thanks Jraef, but in the case I want the same setting for the 3 phases, can I set say only 50-1 (and the relay would understand it's for the 3 phases) or do I also have to set 50-2 and 5-3 equally ?

Thanks,

Mongao

 

[Phil Corso]

Mongao,

The 3 pickup and time settings are used as a 'coarse' representation of the inverse-time function time curve provided by the disc-type ((ANSI 51) mechanical relays!

Regards, Phil Corso

 

[Jraef]

Thanks Jraef, but in the case I want the same setting for the 3 phases, can I set say only 50-1 (and the relay would understand it's for the 3 phases) or do I also have to set 50-2 and 5-3 equally ?

Thanks,

Mongao

Inside of THAT relay, you have what is referred to as a "PLC function" IIRC, which allows you to write your own program to tell the relay how to handle these functions. So using that, you should be able to make it trip any way you want it to trip, usine one, two or all three, set the same, set for different levels (per Phil Corso's post) or even have warning levels vs trip levels.

Assuming from you asking these questions that it means you have never used one of these new relays before, it might be worth it to pay to have a Siemens engineer come out to do at least the first one and train you on them. They are fairly complicated.

Mongao,

The 3 pickup and time settings are used as a 'coarse' representation of the inverse-time function time curve provided by the disc-type ((ANSI 51) mechanical relays!

Regards, Phil Corso

Typical, yes. With the new level of programmable flexibility, you now have more options plus the inverse-time function can be added in programming anyway.