There is the issue of conductor sizing and terminal temperature. If the conductor is at a temperature then any terminal it is connected to is also. This article is helpful:
http://www.eaton.com/ecm/groups/public/@pub/@electrical/documents/content/ap01200008e.pdf
Even if the cb is taking the...
They have new plugs that are adjustable, so it now looks like the other settings, with dials. See for example p11 of the following:
http://www.eatoncanada.ca/ecm/groups/public/@pub/@electrical/documents/content/il01209005e.pdf
My location is industrial, well controlled, and that is supervised. I...
The circuit breaker is 800 A frame and 80% rated, which is 640 A, The adjustable rating plug, can be easily set to say 500 A. The trip unit, which is separate, can be set as a multiple of 500 A. Can the breaker carry 500 A as that is less than 640 A, or does it now become limited to 400 A?
There is a methodology that does include the pre-load in fault calculations, especially mapping network currents. And the motor internal rotor voltages would be less than 1.0 pu if the motor is loaded.
ScottyUK: I was referring to the generator neutral grounding and the generator only. I wasn't referring to the bonding of the plant metal cases, nor to the earth electrode, nor the connection of the bonding conductor to the earth electrode.
No one talked about believing or not. I'm sure it does work, and relies on the fuse. I prefer the approach shown in the eaton Consulting Application Guide, part 10, motor starting, fuse contactor coordination. If the point is to the right we have ensured coordination.
Lionel, for example, 90 ms opening and 4.62 kA, 5 kV. I see 38R listed, but when I plot that point with a Ferraz A480R 18R, the point is not to the right of the fuse total clearing. Doing it that way, an 18R wouldn't work. Either the opening time or interrupting current capability should be...
podobing, for the overload region, on the 4.16 kV, we use a motor protection relay, with the contactor, but only in the overload region. Above that level, in the short circuit region, the fuse should open, not the contactor, and that is achieved by proper coordination. However, if during the...
What you say makes sense. However I am finding a very wide range of stated opening times, with closer to 100 ms (6 cycles) very common in product specs. http://www.joslynclark.cn/up_files/myupload/mvc%20series%28databinuser-2011-12-7-18-39-22%29.pdf...
Medium voltage (4.16 kV system) vacuum contactor dropout time is important for fuse-contactor coordination. Some vendors have values between 15-25 ms, and others, several cycles, which I have been more used to seeing in the past. Compare that to a 3 or 5 cycle vacuum breaker, and 15-25 ms is...
I use both ETAP and PowerWorld and am proficient in both. One is for industrial and the other for the HV grid. Issues and needs are different.
ETAP is the one that has the modules needed for industrial work. Short circuit, load flow, protection coordination, arc flash, motor starting...
