You may want to review your locality's Occupational Health and Safety Rules.
In my jurisdiction, anyone entering a manhole needs to be wearing a safety harness with a means of hauling/winching them out of the confined space.
A Ministry of Labor Inspector would issue a hefty fine (to the...
I believe that the OP formula works for a delta or three wire system if you assume that all quantities are vectors (i.e. complete with phase angles or expressed in complex notation)
One thing that you have to be careful about here is ensuring that you are consistent with the use of RMS or...
We would allow grounding through a switch as long as the CLOSED state of that switch is guaranteed in the permit (motor decoupled if motorized, etc), and one can visually confirm continuity from the permitted zone to the actual grounded point(s).
For this reason, we would not normally accept a...
I forgot to mention that you can also review your historical billing data to detect instances where a customer diverts legacy power usage.
If this year's November bill is much lower than their November bill last year, that raises a flag to check the service out.
That will not help if they have...
Our 'Smart Meters' communicate back to the office.
They have a 'tamper detect' feature that is pretty good at catching when someone is messing with the meter/socket connection.
As others have noted on this thread, that is useless if the bad guys are diverting power around the meter.
There are...
OP did not specify locale.
All of the answers given were for USA.
Setting aside legal/regulatory requirements, your company would still be on the hook for all cleanup and remediation in the event of a spill.
The utility next to ours just had a spill, and it cost them about $600k for the...
As a Utility guy, I always worry about impacts to other loads.
Have you looked at the drop/flicker effects to the rest of the facility? You may have to consider other more sensitive loads on the source side of your transformer. In extreme cases, the Power Utility may specify a maximum flicker...
There's a wealth of transmission unit costs to be found in Link
Table 2-1 shows line budget costs per mile for each voltage.
345kV = $1.34M/mile
500kV = $1.92M/mile
Tables 3.1, 3.3, 4.4 show similar higher costs for 500kV substations vs. 345kV substations
In general, over-current protection devices (like any fuse) ALWAYS go on the SOURCE side of whatever they are trying to protect.
Otherwise, they would not provide any protection!
Don't forget there's another perspective on frequency of motor starts:
voltage sags / flicker on the rest of the system
Your facility may have issues with starts occurring too often, if it affects other equipment or even causes nuisance light flickers.
Your utility likely has quality standards...
The TESTING can be done.
The difficulty is in correlating the <0°C results of frozen soils with the 'warm' results.
From what I understand, frozen soil resistivity can vary by a factor of 50 to 100 from 'wet' soil.
I am not aware of any industry-accepted way to relate the two.
WITHIN the circuit, if you have branches, then the current vectors in each branch can be different.
If the circuit is just one 'loop' with everything in series, then, as David points out, with only two connections to each node, the current vectors (magnitude and direction/angle)are the same.
The main purpose of the 'goof loop' near a splice case is to provide sufficient slack to bring the case down to grade level so that it can be maintained/modified (typically in a van or trailer) rather than while up in the air.
Splicing fiber is enough of a PITA without adding "while poised on...
I was aware that lightning has a very high voltage!
Lightning is not 'hunting' for your phase wire.
It is seeking a discharge path between the air and ground.
If a given stroke of lightning hits a well-grounded shield wire, in my 25 years of experience it will not jump ANOTHER large air gap...
The rule of thumb we have always used is that, since the shield wire is bonded to the ground grid by design, then apply similar minimum clearances from the phase wires 'UP' to the shield wire, that I would use 'down' to the ground.
But I have never found that to be the design-constraining...
@DavidBeach
Even the bushings might not help, as a Delta-to-Wye conversion like you describe likely re-used the transformers, now connected line-to-ground. Just because the H2 bushing is fully insulated does not prevent it from being connected to neutral, which may still be at the top of the...
