Cost Reduction by Adding HRG Units
Cost Reduction by Adding HRG Units
(OP)
HI,
Several folks on this forum, plus discussions with other electrical engineers, has convinced me of the need to install High Resistance Grounds (HRG) units on all of my 480 Volt and 2400 Volt ungrounded delta substations.
I have been allow to purchase one unit, so far, and I am pushing for the $$ to do more. I keep reading reports that indicate the number of motor failures will drop after the installation of HRG units.
Has anyone seen any published data from any studies on the improvements due to the use of HRG units, that I can translate into cost savings? I know there are lots of benefits, such as safety, improved reliability of the process, and improved power quality, etc. It will help if I can use some hard numbers to back up the cost savings.
Thanks.
Several folks on this forum, plus discussions with other electrical engineers, has convinced me of the need to install High Resistance Grounds (HRG) units on all of my 480 Volt and 2400 Volt ungrounded delta substations.
I have been allow to purchase one unit, so far, and I am pushing for the $$ to do more. I keep reading reports that indicate the number of motor failures will drop after the installation of HRG units.
Has anyone seen any published data from any studies on the improvements due to the use of HRG units, that I can translate into cost savings? I know there are lots of benefits, such as safety, improved reliability of the process, and improved power quality, etc. It will help if I can use some hard numbers to back up the cost savings.
Thanks.






RE: Cost Reduction by Adding HRG Units
To me, reducing a most basic, well understood, extensively documented engineering principle to mere short-run budgetary consequences is nauseating.
Approach your seniors from this point of view—take two motors whose failure will choke production, and extrapolate from that. You may find supporting information in IEEE Std 493-1997 Recommended Practice for the Design of Reliable Industrial and Commercial Power Systems.
RE: Cost Reduction by Adding HRG Units
Sorry it makes you nauseated. But that's life in the industrial corporate world today. Just trying to get all of the ammo I can. There are more good projects than $$ to go around. Those that build the best case first, gets the prize!!
Have a good day.
RE: Cost Reduction by Adding HRG Units
10-4 jburn—no argument here. It just seems silly to not apply learning from other's extensive, well-documented experience.
Sometimes it is slightly rewarding to stand back and see production loss from something so stupid. I’ve given up trying to impress [or brown-nose] anyone with my ideas.
RE: Cost Reduction by Adding HRG Units
jburn, please understand that my comments are not intended to be personally offensive.
RE: Cost Reduction by Adding HRG Units
You realize that High-Resistance-Grounding LV systems requires low-level ground-fault detection on all feeders, branch circuits, and utilization equipment. Also, because they are designed to negate the effect of system capacitance-to-ground, there is no "one-size-fits-all" approach.
These considerations may blow your Benefit-to-Cost-Ratio's! Please read the comments on the thread (sorry, I don't have access to the number, at this time):
"The Physics of Electrical Failure: Ungrounded Systems"
RE: Cost Reduction by Adding HRG Units
RE: Cost Reduction by Adding HRG Units
RE: Cost Reduction by Adding HRG Units
RE: Cost Reduction by Adding HRG Units
There are reasons why over 7.5 million motors are sold each year. If you want to have fault protection try low cost stand alone fault indicators put them at critical loads or all loads. Easy to install.
RE: Cost Reduction by Adding HRG Units
fault indicator part number
ABB SC320R0200