We have multiple feeders from a piece of SWGR to multiple SWBDs. These feeders are 1600A’s each so we are running parallel feeders using a separately run #4/0 AWG Ground. The Contractor wrote an RFI in order to try a save the owner money and requested that we run a single ground cable for the...
My background is Industrial so I am coming into this arena with little to no Utility experience. I am working on a design tie a 12 ohm NGR to a wye delta grounding XFMR (The Fault current of the NGR is 1658A for 10sec.) The L-L voltage is 34.5kV. During a fault the NGR can see as much as 20kV...
I am trying to size the NGR's conductor from a wye delta isolation transformer. I believe the NGR is rated 75A continuous and can allow ~900A for 10 sec and has an 8 ohm impedance.
When I model the system using SKM the damage curve of the conductor requires a 500kCMIL cable to withstand the...
OK here's the thing. I normally research my topic thoroughly prior to coming into the eng-tips forums, but I am on a tight deadline to have answers on this topic very soon. So I am apologizing up front for now making attempts at due diligence.
Now that I got that out of the way...
My...
I have been on several Pulp and Paper Projects in the recent past where the project direction took the coordinated drives on a 575V power system and the 480V loads consisted of FVR/FVNR/non coordinated VFDs, etc.
Is this a client preference or is there a motive to doing this? I have tried to...
I am in the middle of attaining pricing and deliveries for Medium Voltage Cable for a MV VFD motor (4000V) application. Some common denominators I am getting from the various players are 5kV 133%/8kV 100%, CLX or CCW or IAC Armor Tape shield, all of the vendors are specifying 3 connectric...
I am working with a Client who has given me a reference to a table from NFPA 70E Table 130.7(C) (15) (a).
The line item from that table states that the task when opening hinged covers (to expose bare, energized electrical conductors and circuit parts) in Metal Clad Switchgear, 1kV through 38kV...
Distinguished Forum Members!
I have a 250HP 480V Centrifugal Circulation Pump that supplies water to a Heat Recovery Steam Generator (HRSG) that we have in our specification to Supply an HMCP for short circuit protection and Motor Overloads for Long Time Thermal limit protection. I have been...
Fellow Code Guru’s:
I have a question concerning the NEC's Article 250 stance on tying in new structures to existing. We have this Railroad elevated tie off structure that will allow the factory workers to tie off to an elevated rail and access the railcars as they enter the area. The owner...
I am in need of some ammunition to take to argue a case that for an industrial facility the owner should NOT even consider using wire basket as a raceway for their catwalk lighting circuits. The owner is trying to think of other methods to save money to this catwalk lighting than the...
I am working on a project where we have temperature elements that are monitoring temperatures that exceed the Type K range (slightly above 2500 deg F).
I Googled cable manufacturers that sell this type of cable and OMEGA (Stamford, Connecticut), Thermax/Lapp (Minneapolis MN), Pelican (Naples...
Does anyone know of a maunfacturer that sells a retractable lighting mast that elevates to ~12 feet. I have a client that needs to install an aircraft obstruction warning light that needs to extend an additional 12' from the top platform of a very tall structures about 90 feet in the air. I...
OK I am curious about a LV Motor Protection scheme. I usually specify Motor Protection Relays for MV Motors, but I have a 200HP 460V Direct Drive Pump that has Motor RTDs. Is the only way to protect the motor with respect to the RTDs through a Motor Protection Relay? Like an SEL 701, or...
I am working on a project where we have fifteen (15) Sootblowers on a Heat Recovery Steam Generator (HRSG). We are trying to develop a disconnect panel to allow the maintenance personnel to switch the power off of the local sootblower starter to service the local starter or anything that has...
According to the IEEE std C37.2-2008 this is an annunciator relay. I have a single line that shows them interfacing with 86 lockouts. Does todays Multifunction solid state relays incorporate this function? The single I am using is a year 2000 era and solid state relays were in place at the...
I have a client that has requested that the low voltage Motor manufacturer provide bus terminations for 200HP LV Motors instead of using motor leads. Now they are concerned that the motor connections will require a space heater to remove condensation. I have never put space heaters in low...
I tried to search the internet about what the NEC says about clearances around junction boxes specifically motor conduit boxes and I saw references to Art 314. Nothing gave me instructions on clearances.
Art. 430-12 addresses the motor terminal housing and its details, but not working...
Please provide information of the differences between a C Face, C-Flange, D-Flange motors. I know that these are drive side mounting verse foot mounting but I don't understand the differences. Any references or explanations are greatly appreciated.
TIA.
JBUDA54
All,
I have a 53 foot x 38 foot structure that will house very large 66" water pipes. This structure otherwise known as a valve pit will be an area to house electrically motorized operated valves. The structure will not require piles for its foundations but will have spread footings. There...
I am working on a project where we have a 2000kVA double ended sub that normally pulls power from the utility from two different ckts. Occasionally the utility source is swapped to local generator power. This swap-over from utility to local generator power is done upstream from my double...
