Isolation xfmr at communication site

[ocsteve78]

I'm working at a communication site which has to meet R56 motorola requirements. Xfmr is a 1- phase 240v primary with H1 and H2 connections. Secondary is still 1-phase 120/240v with X1 and X4 connections for the 240v and a jumper across X2 and X3. Secondary will be feeding a panel with 120v laods. I know that at X2-X3 jumper I'm splitting my 240v to get my 120v. The xfmr has an ESS ground point on the housing tying in the core laminates. I bonded the grounding conductors (EGC) with ground bushings to the conduit and then hit a mechanical lug on the xfmr housing. I was planning to drive a ground rod in and bring the GEC in to hit the ESS and X2-X3 terminations so that my neutral was not floating and bond the xfmr for 120v loads. It seems to me typical of xfmr grounding as a seperately derived system. my confusion is that I'm being told by the Motorola Rep that this is incorrect. that the ESS should be kept seperately only grounding the core and that I ruined the integrity of the xfmr by bonding the EGC from the conduits to the xfmr housing. Any helpful information would be useful

 

[wisp_engineer]

I'm working at a communication site which has to meet R56 motorola requirements. Xfmr is a 1- phase 240v primary with H1 and H2 connections. Secondary is still 1-phase 120/240v with X1 and X4 connections for the 240v and a jumper across X2 and X3. Secondary will be feeding a panel with 120v laods. I know that at X2-X3 jumper I'm splitting my 240v to get my 120v. The xfmr has an ESS ground point on the housing tying in the core laminates. I bonded the grounding conductors (EGC) with ground bushings to the conduit and then hit a mechanical lug on the xfmr housing. I was planning to drive a ground rod in and bring the GEC in to hit the ESS and X2-X3 terminations so that my neutral was not floating and bond the xfmr for 120v loads. It seems to me typical of xfmr grounding as a seperately derived system. my confusion is that I'm being told by the Motorola Rep that this is incorrect. that the ESS should be kept seperately only grounding the core and that I ruined the integrity of the xfmr by bonding the EGC from the conduits to the xfmr housing. Any helpful information would be useful

I work with R56 regularly, but I do not deal on the side of the house that covers the transformer, we farm that out to our EC and the Motorola guys check it. I can look at our R56 doc if you have not resolved this issue. Do you know who the Motorola ST was that you were dealing with?

 

[shepelec]

We always hit the halo ground at tower sites. Forget the rods the halo will give you a much better job.

 

[ceb58]

We always hit the halo ground at tower sites. Forget the rods the halo will give you a much better job.

Very much agreed. The bottom line is the halo and underground ring are all tied back to the electrical system ground with multiple G rods.
As far as the Motorola rep. he is just that. They know the radio equipment but most are fuzzy on the electrical side.
From Motorola's R-56 manual page 271 section 6.2.3 "The transformer creates a SDS where the neutral and ground conductors SHALL be bonded together with in the transformer OR the first disconnect after the transformer and bonded to the building's common grounding electrode system" Then on page 237 fig. 5-27 it plainly shows the bonding as you have done. You can go to Motorola's web site and download the R-56 manual.