Looking for recommendations on 20KW generator protection relay 1

[spark706]

We are building several small microgrids, all of which contain 20KW synchronous generators along with PV and battery. I am a distribution protection engineer with no experience with generator protection and would like to see what relay(s) that you would recommend.

I am very familiar with SEL-651 and SEL-351 relays, so the learning curve there is minimal. But I am not familiar with the Beckwith or Siemens line, specifically the Siprotec 7UM85, Beckwith M3410-A, or the Beckwith 3430 especially in how they compare to the SEL-700G unit. We are not wedded to SEL by any means, instead looking for the right relay for the job.

All units have the same basic protection and controls ability some this is more on the actual interactions or even the usage for a small generator.

Thanks for any help.

 

[davidbeach]

I can’t easily check at the moment, but does SEL still offer the 547?

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[spark706]

SEL makes the 547 but it looks more like a 651 or 751 line relay. We will be using S&C Intellirupters for the PCC connection (another new toy to learn). I am looking for something that will protect the generator itself, or even if this is a concern based on the size of 20KW.

I am thinking that having the Loss of Field, over/under-excitation, or general equipment protection would be import.

 

[davidbeach]

If a 751 is an option then a 700G might be a better option.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[waross]

I have installed several dozen sets in that size range. The typical protection for a stand-alone set is mechanical, low oil pressure and high temperature, and electrical, a main circuit breaker.
Contrast the cost of a replacement generator end with the cost of a relay and associated CTs and installation. Consider that many sets in that size range run for years without failure, with little maintenance or attention.
I would concentrate on distribution protection: Automatic sync and sync check, including reverse power protection and shutdown.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[catserveng]

For that small of a unit then likely your best option would be a small genset controller with electrical protections as part of the package.

Several options are available at reasonable cost from companies like Deep Sea, ComAp, Basler and Deif.

700G's are nice and I get around them quite a bit, but on several recent projects upgrading smaller (500-1000kW) gensets we used 751's as they did all we needed, and didn't pay for the extra features like differential we wouldn't use on units that size.

SmartGen controllers have been showing up around here on smaller units (less than 100kW), but in my experience their durability seems lacking, at their cost many users just buy a spare, but I don't use them in work I do.

I use mostly ComAp Intelilite units for small gens, they have provided good service life, good range of extra options to support balance of plant equipment, decent electrical monitoring and good technical support. They cost a bit more than competative units, but have worked well for me.

MikeL.

 

[spark706]

Thanks for the input. I believe we have a Deif system in the works for this. I will look into that.

 

[Hoxton123]

DEIF are ok