I have run into a difficult situation at a site. The power is experiencing 30% to 80% THDv with a corresponding 25% voltage rise. The worst harmonics are the 59th and the 61st, with lower levels of 53rd, 55th, 65th and 67th. See the attached files showing this distortion. Anyone have a...
Anyone care to comment on this oil blog?
http://540ratblog.wordpress.com/
I'm curious what some of the experts here think of this. His big claim is that his undisclosed film strength test shows the real wear protection an oil provides.
Is there a fuse not normally seen in North America that would be used on 1000VAC motors? The only options I'm finding are 1000VAC rated semiconductor fuses or the 3" diameter x 10" long, 2400VAC, R-rated motor fuses.
I'm looking at a power factor correction case and the utility meter almost never reads above 0.707. There are a few measurements higher but most are either 0.707 or they are lower. The loads are all inductive yet the addition of power factor capacitors has caused the kVAR to appear higher and...
Can anyone point me to any specific references concerning the elimination of ringing on the output of a VFD. I'm looking for some more detailed help here. Just the advise of installing an output reactor or a motor filter is no help.
I will give you an example. We had a call to a failed VFD...
Hello, as the subject says, anyone know of a manufacturer of a surface mount (maybe screw tab) RTD package that is electrically insulated for at least 300V? If not RTD, then a thermocouple package?
Thanks
I have a customer who has requested an insulation monitor that continually monitors the motor insulation when the motor is off and prevents a start if the insulation tests as bad. This would be permanently mounted and as such should be a panel or door mountable unit. The motor is 600VAC and I'm...
Hello;
In many VFD applications there is a braking resistor used to allow the VFD to delecerate the load in a reasonable time. I was wondering if anyone has references to a document showing how to calculate the shortest possible deceleration time given a certain motor, load, VFD and braking...
Hello;
I'm looking for any North American standards or regulations pertaining to oil containment for the indoor installation of 5kV class power factor capacitors. A typical capacitor is something like a 200kVAR 3-bushing can. I have been asked if there are any requirements to install oil catch...
Hello,
Are there any good references or standards for altitude deratings for switchgear? I've seen some info in IEEE/ANSI C37.20.3-2001 but that's about the only standard with altitude derating info that I have found.
