Thank you all.
Based on the J&P document Marmite attached, I can see that there is a load value dependence aside from power factor, as the simplified model in the document is expressed as:
percentage regulation = a[Vr cos(phi) + Vx sin(pi)]
Where a is the load factor (expressed as a...
Thank you davidbeach, so from nameplate alone, we won't know the full details needed to do the calculations.
I'm still confused with the '%' unit for the impedance, and it is my understanding that is based on rated current.
Assuming an X/R ratio of 1 (for simplicity, let's assume Z% = X%)...
Thank you for the comments;
I will reword my question as follows:
The only impedance information available on most transformer nameplates is a Z%.
Let's say the transformer nameplate has the following information:
kVA = 1000kVA
Vpri = 4160V
Vsec = 480V
f = 60Hz
3phase
Z% = 10%
If we know...
Hi all,
Can someone please help me understand nameplate transformer impedance values better, and how it can be used for varying loads.
I realize that the nameplate transformer impedance (let's call it Z%) is by definition the voltage (in pu) that causes full load current circulation in the...
Dear all,
We have an application where we are installing low voltage CTs on a medium voltage system.
The CTs will be installed on insulated cables on the secondary of a transformer, that is operating at 5kV.
As you are aware, it is fine to use LV CTs on MV systems as long as the system has...
Thanks; I should have clarified, I meant besides the harmonics. In our application, the voltage harmonics levels from the utility is actually satisfactory (~1.3%); when our VFD is running voltage harmonics goe up a little but still within the required 5% for the voltage class. What I want to...
Dear colleagues,
I have a few questions with regards to power quality standards.
I will first outline the application I am currently working on and the reason that I'm raising these questions (background).
Background:
I'm working on a relatively large-sized VFD application; this VFD feeds a...
Hi all,
Does anyone know what kind of PTs would be suitable to use for harmonics measurements?
Note that in our application we need to do harmonic measurements at a high voltage bus, and since our measurement device can only go up to 1000v, we need to use a PT to step down the voltage to feed...
