Thanks for all the input. I agree that 12 pulse is overkill. I agree with DickDV in that an overall network analysis should be done however the client is focused on only the VFD contribution in isolation.
I have a client who wants to keep the Total Harmonic Distortion for current less than 5% at the VFD breaker. What is a reasonable value of % current THD that would be expected for a 12 pulse drive? Supply voltage is 480 Volts.
Motor sizes range from 10 to 50 HP
I know that to estimate the load for a building the receptacle demand is calculated by taking 100% of the first 10kW plus 50% of all recept load over 10kW.
I have been told that this applies to panelboards also, however this does not seem logical,i.e. suppose I have 5 panels and they each...
Panelboard load Calculations and demand. I know that to estimate the load for a building the receptacle demand is calculated by taking 100% of the first 10kW plus 50% of all recept load over 10kW.
I have been told that this applies to panelboards also, however this does not seem...
I am trying to calculate cable derating factors for underground Medium Voltage EPR (15kV)cable using the
Neher-McGrath formula. Can anyone recommend a good handbook
with calculation examples?? The cables are assumed to be in concrete encased duct bank.
Any help would be appreciated
I have an application that requires a diesel driven pump rather than an electric pump with a standby generator.
My question is how to handle ventilation requirements. The unit will be located in a basement below grade with access to louvers in wall at grade. The engine is approximately 50 Hp...
I want to thank all those who have responded to my original posting RE: Electron Microscope installation and magnetic fields. From the many responses I received it looks like I'll use the empirical approach and do some local measurements.
Going back to fundamentals, a coil of wire used with...
I have an electron microscope installation I'm working on and one of the requirements is that any magnetic fields in the vicinity of the unit be less than 1.0 milliGauss at 60Hz. There are four 208/120 Volt 3-ph panelboards located on the corridor side of the room partition. The panels are steel...
I have an electron microscope installation I'm working on and one of the requirements is that any magnetic fields in the vicinity of the unit be less than 1.0 milliGauss at 60Hz. There are four 208/120 Volt 3-ph panelboards located on the corridor side of the room partition. The panels are steel...
Thanks all for your responses to my question on isolated grounding. There seems to be a wide range of opinion on how useful isolated grounding really is.
[bigsmile]
I know that isolated grounds are used to reduce common mode noise;
Who originated the concept. I know that at one time Wang PC's/ terminals were required to be on circuits utilizing isolated grounds, but is the concept still valid for today's computer/data systems and is it worth the extra...
What is the proper way to size transformers for double-ended switchgear?? For example I have a switchgear with a left and right section with a normally open tie breaker . Each bus rated for 4000A. The load on each side is approximately 3400A at 480 volts 3-ph. If one transformer fails is it...
