Recent content by Audun

What is the "normal" three phase voltage in the US ? 440V, 460V or 480V ?? Offshore is normally 440V but motors made in US are 460V and someone claims 480V. Do you use 460V motors as a standard? Since I'm in Europe I have no clue, but need the info.... Audun

I know there is a way of using passive components, and this is what I want. I don't have the book dpc refers to, so please describe it in detail... Audun

I'm wondering if anybody has a setup for measuring negative sequence currents. (using 5A CTs) Anything analoge, not digital please. Audun

I think I will interpret as follws. Fault make: Subtransient short circuit current. Fault break: Transient short circuit current. If anybody thinks this is wrong, please let me know. Audun

The levels is indicated in a technical project description. 2.0 Electrical supply system and tolerances ..... ... 2.3 Fault levels * 13.8 kV System - Fault make, 1.5kA, Fault break 1.0 kA * 440 V System - Fault make, 25 kA , Fault Break 1.7 kA As you can see, it is not in a breaker spec, but...

What does "fault make", and "fault break" represent when indicated for a systems fault levels. I'm only used to transient and subtransient short circuit currents. For a breaker I know what make and break levels indicate, but I have never before seen it used for system levels...

What is the difference between those two ? Audun

What happens to SF6 above 45.6 deg.C, since this is stated as a critical temp for use in a SF6 CB? Audun

That is probably right. The damping windings will induce current and work against the contrarotating field ensuring less induction/eddy currents in the rotor metal. Maybe the current in the damping windings don't cause as much heat as the eddy currents would do. Audun

The permanent magnet rotor is to my understanding just a separate feeder for the main magneticing circuit.(or else there would not be possible to have voltage regulation) How this helps on the heating problem is what I don't understand. The main rotor still have to have field windings. Maybe the...

Hi folks. I have tried to find what recomondations there are regarding negative sequence currents in generators. Standards state max 10% of rated current, but Aggreko told me their rental gen.sets could handle 33% negative sequence currents. When I asked why they differ from the standards, they...

Since I had a datasheet beside me, here you are... Typical syncronous generator data: Voltage: 480 V threephase PF = 0.8 Power = 1150 kVA Freq. = 60Hz X'd = 0.157 p.u X''d = 0.122 p.u Xq = 1.210 p.u T'd = 0.132 sec. T''d = 0.010 sec. Audun

Is insulation thickness the same for XLPE and EP-rubber for same voltage rating ? Audun

Hi What guidlines do you know regarding unsymmetrical threephase generator load. My question relates to the following case: 480V diesel generator. Load currents for phases are approx. 2000 A, 2800 A, 800 A PF=0.8 What generator rating is recomended. I think there are som production standards...