Recent content by dithomas

Tugboateng The ground lights at the brewery had a bulb test circuit that was a good feature. They tries LED bulbs at one time an they did not work, all three lights stayed on even with a ground, so went back to incandescent. The bub filament was an important part of how the system worked. The...

Hi Jraef, I have seen this configuration twice. One facilty had three separate services each installed with an expansion. The oldest one was the high leg and the other two were the normal 480/277 services. That project was to combine all of the services into a new single point of connection...

Thanks to all. My memory has been properly refreshed.

When I was still working I ran across a 3 phase electrical service where the utility supplied power to a facility using three pole mounted transformers with one transformer being larger than the other two. I can not remember the details, but it seems to me that one of the transformers supplied...

Hello all, know that drives and other power electronic devices do not belong connected to an ungrounded 3 Phase 480VAC delta supply but this is a plant built in the 1960's that does bottling and these systems were common at the time and obsolete for new tech but this is the hand that has been...

Hello all, I have a short video attached of the ground indication lights on the secondary bus of a 1000kVA 13.8kV deltla / 480V delta transformer with ungrounded secondary. There is a 3 phase rectifier connected to one of the 600 amp feeder breakers. The DC bus of the rectifier is to be...

Hi Bill, Thanks for the reply. Rather than the roll your own approach I am looking for a replacment retrofit controller that is already preprgrammed and from a vender that can provide long term service and support. I am looking for somthing like the Woodward DTSC 200 that can handle a...

I first posted this in the motor and generator forum but thought I should have posted it here also. I am on the hunt fot a replacment controller for an existing PLC based Westinghouse Auto Transfer. The existing scheme uses three 15kV WLI Switches as a Main - Tie - Main with a preferred and...

I am on the hunt fot a replacment controller for an existing PLC based Westinghouse Auto Transfer. The existing scheme uses three 15kV WLI Switches as a Main - Tie - Main with a preferred and alternate untility feed. The two main ssitches are fused. The Westinghouse PLC is obsolete with no...

I am wondering if anyone has seen this type of Vibration Spectrum Data before and may have some idea as to what it respresents. The data is from the drive end motor bearing of a 50 HP induction motor on a belt driven fan. The motor is controlled by a VFD. This signature appeared in...

Parchie It is possible to remove the ground conductor from the ct window. The cable breakout was above the CT. I have attached a photo. Danhttp://files.engineering.com/getfile.aspx?folder=fe9485df-b7be-4735-98bf-9f875042ce57&file=540_Ton_Chiller_GFI_Coil.jpg

Thanks unclebob.

I have a 540 ton 480VAC 3 PH Y-D closed transistion starter fed from a Y solidly grounded transformer secondary. The compaint is that the chiller may experience a ground fualt trip on the first start-up after not running for a long period of time. The gfi is reset and the chiller starts and...

jscwei314, That is a rather good riddle!!!! The 69 kV line is an unregulated line and my swing 10 to 15 pecent. If and LTC is on a transformer and left on one tap coking can form on the contacts. Will vfd and 2300 volt motor tolerate a + - 15% swing? What is the weather like? D

Has there been documentation or studies done on the failure rate of the old Westinghoue 13.8kV UTT on load tap changers? These are the units with arching type transfer switches. I have two if these units in service built in 1967 and on 12MVA 69/13.8 transformes. Both with close to 400,000...