Function 50 and 50P

[giordanonaval]

Hi!
¿Does anyone know the diference between the protection functions 50 and 50P. The same thing with 51 and 51P.?
Im not taking about 50/51N
In some projects I saw that engineers make diference between 50 and 50P

Thanks in advance

Martin

 

[jghrist]

50P usually means phase instantaneous overcurrent. 50 usually means the same thing.

 

[giordanonaval]

That's the point!
Usually menas the same, but protection engineers make diference between 50 and 50P. That way my question

regards

martin

 

[dpc]

If these are Schweitzer relays, they generally use P to designate Phase functions. Some protection engineers have elevated SEL internal relay designations above IEEE and ANSI standards.



David Castor

http://www.cvoes.com

 

[slavag]

It's same 50 and 50P.
In few newer relays used also 50P-1, 50P-2.
Actually it's DT overcurrent function.
Best Regards.
Slava

BTW, for example: Siemnes 7SJ800

 

[relay21]

Before there were multifunction numerical relays, there would be a 50 relays for phase protection and a seperate 50 for zero sequence protection 50N. With the newer relays there needs to be a way of differentiating between the different available protective devises included within the one packaged relay. 50P, 50N, 50R, 67P, 67N...

Gabe

 

[jghrist]

Usually menas the same, but protection engineers make diference between 50 and 50P.

Give us an example in context.

 

[Ohmly]

Engineers & manufacturers often get the numbers mixed up - I never rely on these numbers. Have seen costly mistakes made, and many unneccessary arguments because of this numbering system.
Get the person who mentioned the numbers to clarify the application - asking others to interpret what another person intended is normally the cause of the mistake/argument.

 

[rbulsara]

Get the person who mentioned the numbers to clarify the application - asking others to interpret what another person intended is normally the cause of the mistake/argument.

Can't agree more!

Rafiq Bulsara

http://www.srengineersct.com

 

[ijl]

I have seen '50', or actually '50/51' been used about combined overcurrent relays. The relay contains different functions, or modules, such as 50/51P for positive sequence, 50/51G for zero sequence (residual, ground), and 50/51Q for negative sequence currents.