My company has plans to repurpose an existing 4 kV, 700 hp motor presently driving a 700 hp centrifugal water pump. The existing pump is being replaced with a smaller pump that requires only about 300 hp. What changes in the motor's existing protective relay settings, if any, would be...
Would anyone happen to know the equation for the tripping time of a North American Class 20 thermal overload relay? If so would you mind enlightening me?
Gentlemen,
An AE firm came up with the settings for a Siemens WL breaker with an ETU trip unit. I think they used SKM software to get the numbers.
This involves a recently installed Goulds reclaim water pump driven by a Reliance 460 V, 250 hp motor. FLA=272A. LRA=1825A.
Trip Unit Settings...
I did more research and found some interesting details that had been left out of the original material that led to my question.
Apparently a buildup of the measured medium on a capacitance probe can be modeled as a long string of infinitesimal series resistances with infinitesimal capacitance...
According to the literature of one manufacturer their capacitance-based level instrument using RF admittance techniques is able to distinguish between the capacitive RF current through the medium's level as well as both the resistive and capacitive components of the RF current through the...
Thank you both very much. That clears up a heck of a lot of confusion on my end. Of course there's still plenty of confusion to go around, but less than before.
Mr. Bvanhiel,
The McMaster site has a wealth of information on metric screws as you found. It appears that all the information I need is there. This will help me identify metric metal screws when I encounter them. Thanks for your help.
Efunda and Engineer's Edge both contained a wealth of information but not much on metal screws. Thanks for these references. They will be valuable resources for other topics.
Maryland Metric did indeed have a table for metal screws. It appears to have the info that I was looking for...
Thanks for the link Mr. Julep. Much appreciated.
That standard is not worth $50 to me. My interest is a casual one. Numerous sites on the Web have tables for thread sizes. Do you know of any that has the information in this standard?
Folks,
My extensive Googling has not borne any fruit in regard to metric metal screws. There is such a thing as a metric metal screw, is there not? Do these things use the same thread pitch and diameter as standard metric machine screws? Where could I find some specs for these fasteners?
You, sir, are exactly right. My purpose in approaching this august group was to learn more about the kinds of equipment others are using for similar applications at their facilities, but obviiously I've done a horrible job of posing my questions.
I intend to find out if CH built this equipment...
"By your own admission there have been accidents, at least the one you mentioned, it could have been lot worse. So instead of trying to find obscure limitation in laws and regulations to justify a dangerous installation, fix your systems and practices."
I can't figure out how you came to this...
With all due respect, sir, the circuitry we have been discussing in this thread is installed in a very large coal fired power generating station that was designed and built in 1970 by one of the country's largest two utilities.
Over the years I've been told that facilities like ours are exempt...
Folks,
I very much appreciate your responses.
Let me clarify a few things.
The person who was burned was an operator restoring the equipment to its in-service status after a clearance (tag out) was released.
There is no disconnect for this 250VDC motor operated valve; however, there is...
Recently at one of our sister plants an employee was burned when an arc occurred as he was inserting the fuses for a DC motor operated valve. What caused the arc is still under investigation.
However one of the persons who is involved with the investigation issued a proclamation which blamed...
Dear Mr. Pete,
Thanks for giving my question so much thought. I can follow your reasoning fairly well, and feel that yours is a valid approach. Very enlightening.
A clarification please . . . the (evalf) item in your pdf explanation . . . what is that? A software result or something...
Folks,
We started for the first time recently an 18000 hp induction motor: 13.8kV, 900 rpm. The Multilin 469 relay took it out immediately on short circuit. In round numbers phase C current was about 8000 amps, while phases A and B currents were the same at 4500 amps or so. Normal starting...
Several excellent points have been made.
More info for you:
Since I'm already on retirement health insurance and life insurance are already taken care of.
My overhead should be almost negligible. Will likely pawn off printing of instructional materials to the company.
I will not get paid...
