I'm needing a good rough estimate of the cost per mile to build a 50 mile 138KV, 1272 ACSR transmission line in the central US excluding land acqusition cost? Route is straight, land is flat, mostly open range and sparsly populated. Considering wooden H-frame or concrete structures. Sorry, I...
Problem is on the distribution (12.5KV) lines. All of the individual 480V vfds are working together to corrupt the grid PQ.
Any new drives added automatically are subjected to the harmonics.
We are having problems in the field with drive trips, fuses blowing,etc caused by high level 5th order harmonics on our lines. With over 1000 6 pulse vfds installed and little or no filtering on the drives, the voltage distortion is really bad.
The thought is to have half of the sites pole top...
Good feedback.
Looks like the motor is down for the count. We do have another 1000HP GE motor at another site in USA that is available but I'm not certain if it will fit. It is a frame size CD6270 versus CD6766 that came out. Electrical specs are similar althoght rpm is 1600 versus 1200.
Does...
A couple of days ago we had a failure of a GE 1000 hp extruder motor on one of our films lines here in our plant. The motor had a lot of water and ice ingested into the air intake from the roof during the snow storm shorting out 2 of the 6 motor field windings.
The motor shop says the repairs...
We had a driveshaft failure that bent the worm shaft on a Flender Cavex CFW 250 gear reducer ratio 16.67:1. We have ordered a gearbox from Flender but it won't ship until mid-December.
Anyone have an idea where to look for an emergency replacement gearbox maybe on the surplus market...
sed2developer,
The Siemens drive is a model 6RA7091. Talked with our in-house technical person and he found the relavent parameters for this drive to configure it for a PTC 600 ohm thermistor.
We popped the peckerhead on the motor and found that the 3 thermistors in the motor are wired in...
We recently had a GE 600HP DC motor suffer overheating and destruction when the cooling air intake became blocked by debris. During the the investigation it was discovered that the motor overtemperature devices (thermistor - GE p/n 36A172828BBG01) were not configured to work with the Siemens...
Thanks UKpete & stardelta for the suggestions. After considering your thoughts on the matter and visiting with the brush rep (he too warns about relying on wear sensors even though they sell them), I have decided to drop the alarm circuit project at least for now.
The brush munufacturer makes...
I'm looking at adding BW detection and alarm to dc motors ranging in size from 2HP to 1000HP.
We are currently measuring and recording brush lengths at each PM turnaround and will be generating statistics on wear rates. I would like to install one sensored brush in each motor if possible and...
I am researching methods to retrofit a bunch of dc motors in the plant with indicator lights to let someone know when its time to replace brushes in the motor.
I see where one of the brush manufacturers has come out with an embedded sensor in their brushes that can be used to signal an...
Wareagle, Overall demand is just above 20MVA and we operate 24/7. Our demand is close to flat which makes our utility company happy.
Keewee, I wasn't involved in the decision, but back then we had a very capable retired power company consultant in the plant and his recommendations were acted on...
Keewee - The 2250 bank was installed back in the late 80s because our local utility was threatening to impose pf penalties, however, they never got around to enforcing them. We installed the PFC bank at that time. The LV banks were installed in the late 70s and early 80s as the plant was being...
We currently have 10 200KVAR capacitor banks scattered around the plant on the 480V side that have failed in the past 25+ years and were not repaired. At the plant service entrance there is a 2250KVAR bank on the 12.5KV side that has been maintained and is working.
Our power factor runs at 0.8...
Some years ago we had an 800hp dc motor on an extruder run away with disastordous results. Following maintenance work, it was started with the motor uncoupled from the gearbox and the field wiring was inadvertantly left disconnected.
The armature actually blew through the end casing shooting...
Followup:
We increased the field current from 0.7A to 2.25A with the following results:
Motor speed = 825RPM
Armature current dropped from 77A to 37A!
We expect this will take care the rapid brush wear problem and future motor failures due to winding insulation premature failure.
Thanks for...
Nameplate:
50 HP,500 VDC,1750 RPM,328AT FRAME,
DRIPPROOF,83 AMPS,300 FIELD VOLTS,2.25 FIELD AMPS,
CLASS F.
Speed range varied by product but is between 40%-100% normally.
You are correct in that the dc drive varies armature voltage to control speed. Field current is regulated as previously...
