SIEMENS relay has 3 "ANSI 50" functions...(?)

[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

 

[davidbeach]

I know nothing about Siemens relays, but the relays I use have multiple 50 settings. Each can be assigned a different time setting for definite time tripping; any can be used in other functions; SOTF may have on 50 element that isn't used for anything else, forward and reverse elements can be set a different pickup levels. The uses of three levels are limited only by your imagination.

 

[stevenal]

User configurable. You might use 50-1 at a lower setting that allows reclosing, 50-2 at a higher setting that doesn't, and 50-3 enabled by a relay input connected to a toggle that puts it into a "maintenance mode" lowering arc incident energy exposure.

For your simple example, I would pick one and disable the other two to keep things simple. You could set all three the same for redundancy, but it would be a rare failure that would affect only one element in the same relay.

 

[Mongao]

Thanks for replying, it's much appreciated !