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,
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...
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The Westinghouse PLC is obsolete with no...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...
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...
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...
Can anyone share with me some thoughts on the pros and cons to retro fit a 75HP 480VAC coolong tower fan with a VFD?
The motor is the original motor (I have not rewind history) and has six motor leads to the 2 speed reversible starter.
The 480VAC 3 phase system feeding the fans is a Delta -...
If I have an unloaded 1500 HP 700 VDC shunt wound motor how can I determine the voltage and current levels, starting from 0 volts and ramping up, that it would take to first get the motor to roll that run at full base speed. I know that to get to full base speed I will need 700 VDC and full...
I am working on restoring a 1920 Detroit Electric Car. There were no fuses in the battery circuits and I want to install fuses.
The car has two battery packs, one in the front and one on the back, each battery pack is 42 volts DC with 240 amp/hour capacity.
From what I have been able to...
I am searching for a way to determine the losses on 40 year old Federal Pacific 1000kVA 13.8kV - 480 delta delta transformers in order to compare them to a new modern transformer. A saving in operating cost could justify replacing the 14 FPE transformers with new Delta Wye units.
There are 14...
I am looking for suggestions on were to find sample arc flash analysis specifications for an existing industrial plant not new construction.
Thanks in advance.
The foundation of a 50 year old 1000 HP reciprocating compressor was recently rebuild. The synchronous motor is of the type where the rotor is attached to the compressor shaft. It is now time to get the stator back in place and aligned.
How does one account for the magnetic center of the...
I did find an old thread on this topic but there was never a conclusion.
I have a problem with a 480VAC chiller with a Y-Delta starter. The motor is rated at 390FLA.
If the building is in operation with lights and conveyors running at around 350 to 400 amps and the chiller attempts to start...
Been riddling over if a meter with wave form capture would provide enough information to sort out a down stream phase or ground fault.
The system voltage is 13.2kV with a main breaker fitted with an SEL protective relay with phase and ground fault. The 12 feeders are Westinghouse WLI fused...
I have a 1000kVA ITE Askeral filled 2400V - 480 Delta-delta transformer still in service at an industrial plant in an indoor location. The unit was manufactured in 1964.
There was a PF test performed in 2008 showing %DF @20c for H -l&G of 1.36, Watts 1.38, and capacitance of 6700 uf. This...
A 2300v 1500HP motor driving a screw compressor is started by a GE Limit-amp vacuum contactor reduced voltage starter with 3 coil auto-transformer. The 65% tap is used. This starter has been in service for over 10 years.
On two occasions in the last year during a lighting storm the utility...
My question has to do with providing for ground wire monitoring when there is a 12,470 3 phase pole line at the dredge location and the dredge is fed from a 12,470 trailing cable. dredge is in the USA.
Is there a need for a 12,470 delta/wye isolation transformer at the base of the pole in...
Looking for thoughts and comments on the application of a ground check relay to monitor the condition of the grounding conductor on a 12,400V system feeding a sand pit dredge with a trailing cable.
The installation is in the USA.
Thanks in advance.
