For outdoor cable terminations (cold or heat shrink) between extruded shielded cable and rigid-bus open-air rack - I have not been able to locate any specific short time withstand ratings supplied by vendors (such as 3M).
Vendors do provide applicable BIL ratings. In addition, documentation...
I am an electrical engineer for a North American municipal electric utility. I am having a disagreement with my boss over the rating of a new medium voltage disconnect.
Project details:
- New disconnect to be installed in existing 35 kV open-air rack.
- New disconnect will be used to open...
The electric utility I work for recently experienced a 4 kV Overhead Distribution Circuit line down, where all 3 phases of 4 kV circuit burned clear mid span. Span where 4 kV circuit burned clear had double-ended construction on both sides, so there was no significant tension on this span. All...
The utility I work for currently utilizes SKM PowerTools and Milsoft Engineering Analysis (EA) software.
SKM PowerTools is used for short-circuit, load flow, and device coordination.
Milsoft EA provides a GIS based model that can complete short-circuit and load flow based analysis. The device...
I am working on a 4.36 kV, 4-wire distribution circuit from a solidly-grounded delta-wye substation transformer with a connected load of 3,000 KVA.
The connected load of 3,000 KVA is comprised of multiple 50 KVA 1-phase distribution transformers connected 2.4 kV L-to-G balanced across 3...
I have a cold load pickup (CLP) question related to a SEL-351R relay. SEL-351R relay protects a 4.36 kV 4-wire circuit with the following details:
- Peak Phase Load : 280 Amps
- 51P Pickup : 560 Amps
Circuit recently tripped during peak conditions and was out-of-service for 2+ hours. SEL-351R...
I have an application involving a 1,200 foot run of OM4 laser optimized 50/125 um multi mode fiber optic cable. I have a new device that needs to communicate over this fiber link, but it only comes with a LED light source. Specs for new device are:
Light Source: LED
Data Rate: 100 Mbps...
At the utility where I work, a new 27 kV gas insulted switch with vacuum interrupters is exhibiting inconsistent test results across A, B, and C phases. Here are the test details as completed by utility:
1) All phases passed 1-Minute 40 kV AC Hi-Pot Testing.
2) B Phase exhibited a decrease in...
I am looking for any utility experience with installing overhead fault indicators on overhead primary tree wire. Overhead primary system is 4.36 kV, 4-wire and to date overhead fault indicators have only been installed on bare aluminum conductors.
Tree wire is single layer w/ polyethylene...
What is the likely overvoltage that would result during a primary neutral break to an overhead single-phase distribution transformer rated 2.4 kV Line-to-Neutral that provides 120/240V three-wire secondary service?
A secondary voltage of 156 V was measured on one of the secondary legs to ground.
I am working on a project focused on the detection of downed energized primary overhead lines to support wildfire mitigation on exposed feeders.
Looking at the SEL-451 relay with Arc Sense Technology (AST) high-impedance fault detection. What other technologies / grounding should be considered...
The utility I work for just completed a Smart Grid Business Case. One of the identified benefits of the Smart Grid is having customers shift usage from on to off peak periods.
For each KW of on peak demand shifted, consulant used a deferred T&D capital benefit of $685 / KW - Year based on a...
I have been asked to review proposed changes to the California Public Utilities Commission Feed-in-Tariff, specifically the allowable size of PV systems that can be interconnected to distribution systems. Note that these proposed changes are under consideration as a result of increasing the...
Related to electric utility Advanced Metering Infrastructure (AMI) projects, whereby revenue meters communicate to the utility via a wireless RF network, are other U.S. utilties considering using this same RF network for traditional distribution automation applications (i.e. wireless RF...
I assume that I am not the only U.S. utility engineer that has been "reassigned" and tasked to implement a Smart Grid project. I am curious if this is the proper forum to post such questions, as many will include automation and telecommunication elements not typically posted in a Power...
The utility that I currently work for has an approval process for 1-Family Residential Solar Systems that limits the installed capacity to the average annual energy consumption for the previous 2 years of electric billing history.
I have recently "rejected" several such Residential Solar System...
I have an application for a 15 kV, 133% EPR Insulation (220 Mil) underground cable that needs to fit in 2" Conduit (1.913" I.D.). I only need an ampacity of 70 Amperes, but have been told by my local Okonite rep. that they will not manf. a medium voltage cable smaller than #2 CU per NEC Table...
In an ironic twist, having provided the Utility Fault Current data to a multitude of customers in order for them to complete Arc Flash Studies, I have been informed by my Utility Safety Officer that we will need to complete our own Arc Flash Study per the requirements of the 2009 NFPA 70E. In...
I am seeking clarification about the zero sequence network connection for the following three-winding transformer:
High: Wye-Grounded (connected to utility source)
Nominal KVA: 16000
Rated Voltage: 34400
Medium: Wye-Grounded
Nominal KVA: 16000
Rated Voltage: 17200
Low: Delta
Nominal KVA: 2400...
It seems like every software I use has different entry parameters for three-winding transformers. I think I have an analysis setup correctly in SKM PowerTools for the following three-winding transformer, but wanted to check to make sure:
Primary: Wye-Grounded
Nominal KVA: 25000
Rated Voltage...
