Cost Reduction by Adding HRG Units 2

[jburn]

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.

 

[busbar]

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.

 

[jburn]

busbar,

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.

 

[busbar]

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.

 

[busbar]

jburn, please understand that my comments are not intended to be personally offensive.

 

[Shortstub]

jburn,

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"

 

[yinger]

Fault detection equipment does not need to be added at all, it only makes fault location easier. There are many ways to assist in fault location starting with the origional ground lights and improving to the pulsing fault locators built into the high resistance grounding system. Also high resistance grounding does not negate system capacitance, it uses its voalue to correctly size the desired fault current setpoint to limit transient overvoltages. Also a high resistance grounding resistor with taps of 1 to 5 amps satisfies 99.44% of all HRG requirements so effectively one size does fit all.

 

[ajitbapat]

I have not seen any published data indicating effect on motor failures yet. However HRG does reduce the Risk of Fire and Loss so if you ask your Insurance co. to do a Risk analysis for a properly installed and maintained Ground Fault protection system with an HRG, it might lead to a lower risk and hence lower premium which would allow you to write up the justification for converting all or more substations to HRG

 

[jbartos]

Suggestion: The age or aging of the power distribution and its load is also important. If the power distribution and its load are relatively new, there may be very little what could go wrong. However, if it ages, e.g. after two or three decades, the malfunctions/faults happen more frequently. At this time, the high resistance grounding should get a serious consideration, if it fits there. However, even the relatively new power distribution may require the high resistance grounding urgently, if the power supply is for more expensive processes and downtimes are costly.

 

[edjh2]

jburn

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.

 

[edjh2]

jburn:

fault indicator part number

ABB SC320R0200