PS, I also found reference to UL 347A (draft) in NEMA ICS 61800-4-2004 (Adjustable Speed Electrical Power Drive Systems
Part 4: General Requirements—Rating Specifications for a.c. Power Drive Systems above 1000 V a.c. and Not Exceeding 35 kV).
It is referenced in the test section under short...
Thanks for the responses. There is a reference on the UL site to 347A (see link), but I was not successful in getting additional information from UL.
http://www.ul.com/controlequipment/standards.html
I have seen reference to this standard from at least four manufacturers of medium voltage...
Has anyone seen a copy of the Underwriter's Laboratory (UL) standard 347A Medium Voltage Power Conversion Equipment, and if so can you comment on its' usefulness? Most of the medium voltage drive manufacturers list conformance to this standard in their drive specifications, but I have not had...
I should have mentioned that PWM effects will be negligible. This is a custom unit with a high PWM frequency and very effective output filters - EMI could be an issue but transducer and data acquistion system location will be chosen to minimize. Also, the input transformer provides a...
Hello all, I am starting to investigate the measurement/calculation of full load efficiency for a ~1000hp medium voltage motor drive. I would like to get the efficiency as accurate as possible (hopefully to a tenth of a percent - with some uncertainty of course). My plan is to calculate the...
Check out NEMA MG-1 part 20 (or IEC 34-1 paragraph 4.7 for non US) for preferred motor voltage ratings. I believe above 10,000 HP either 6.6 kV or 13.2 kV is preferred by NEMA, but there are always exceptions and consideration of the distribution system and other loads may dictate the best...
Could a sine wave filter be applied on the output of the drive instead of using a new motor? I would expect this to be less expensive provided this meets applicable regulations.
I realize ship speed will be reduced due to the increased load (drag). However, can the motive force remain at the same level, or will it decrease due to motor and drive limitations (i.e., torque limitation).
I have a theoretical question that myself and some colleagues are debating which I'm hoping someone can shed some insight on.
Given a ship driven by a propellor via an electric motor and motor drive is operated at rated current and voltage which produces rated ship speed. What is the affect of...
Hi all, I have an older 200 HP Reliance RPM DC motor (stab. shunt) with a dual voltage field (300/150 Volt). The armature is 500 volt & 320 amp. The speed is 1150/1750 RPM (constant torque to 1150 w/ blower and constant power from 1150 to 1750). I've measured the resistance of both field...
As a final update, I've uncovered the root cause of the problem which ended up not being related to opening of downstream relays, but opening of the transformer primary with no load. After reading several MOV application notes, I overlooked the common problem of interrupting transformer primary...
The diode bridge is rated for ~30 A DC and the peak reverse voltage is 1600 V DC. The circuit operates at 600 V DC. The fuses are rated at 15 A AC ( applied line side of diode bridge) while the largest load is only 12 A DC. The pre-charge current is 6 A DC peak (100 ohm pre-charge resistor) and...
We have been using diode bridges (six diodes in a single package) that have been failing occasionally. Line side fuses blow just as current (load) is applied to the bridge. The load is very small (significantly under the rating of fuse and diode bridge) as it is only a pre-charge of a capacitor...
Assuming the voltage and current are sinusoidal, wouldn't the power factor be the cosine of the angle between phase voltage and phase current? If line voltage and phase current are observed on a scope, wouldn't you expect to see a 30 degree phase shift for a unity power factor since the line...
Anyone know of a source for a used torque transducer. My application is a motor test stand that is 200HP at 1200RPM (~875 LB-FT) [maximum]. I can't affort new but would like to install one on the test stand if possible.
