Hi,
I have a question regarding fall of potential ground testing. I'm familiar with the common FOP methods, including the slope method. However, my question relates to test electrode measurement when the surrounding terrain is not flat. Example, I have a substation grounding system at the...
Hi,
I have a quick question regarding the MiCOM P122.
In the relay manual it states that the operation TIME tolerance for thresholds I>, I>> and I>>> is +/- 2% +30...50ms. Therefore, am I correct in thinking the NEGATIVE tolerance for a set curve is 2% of a set value. Also, that the POSITIVE...
Thanks for the replies.
Can someone explain why connection to the 5A input would be ok? As the CT is only rated at 2.5VA and the relay manual states a 7.5VA burden is needed when using the 5A connection.
Also, I have since found some 1A secondary CTs with a rated burden of 3VA. Would there be...
Hi
Thanks for the reply. Just checked the relay and in does have separate 1A and 5A inputs.
Why couldn't I connect the 5A secondary to the 1A input? As I say, I'm confident the secondary normal running load won't exceed 1A.
Thanks again in advance.
I have a quick question about current transformers.
I have a relay that requires a CT with a burden of 2.5VA (1A secondary CT) or 7.5VA (5A secondary CT).
I only currently have access to a 400:5 (2.5VA burden) 5P20 CT. However, as my fault and load current is low (less than 80A and 1600A...
@davidbeach I'm sure this is only correct if the Wye primary is not connected to the system neutral. If the neutral is connected, current will flow in the line and neutral for a line to line secondary fault.
Thanks,
Thanks for everyone's replies and help so far.
Would it be possible for someone to sketch the sequence network? As discussed, I can calculate the secondary current. However, I'm not understanding how I then determine the primary currents. This is not just due to the Ia1 & Ia2 -/+ 30deg. phase...
Hi,
I'd be grateful if someone could provide me with some help. I'm trying assess a wye (primary), delta (secondary) transformer under a secondary line to line fault. I have determined the secondary fault current in phase B and C using symmetrical components. However, I'm unsure how to obtain...
This thread is regarding closed thread238-106630 which discusses the use of symmetrical components to study load imbalance.
Figure Fig. 21(l) as given by jghrist (from the T&D book) appears to indicate that two of the loads (Zb) have identical impedances, is this correct? Any idea how this...
Thanks for your replies.
However my original post was probably a bit misleading, I should have said that the load was connected between two lines (not phases) of the secondary.
So to summarise, a YNd11 transformer just feeding a sole single-phase load
Hi,
Please can someone give me some guidance or point me in the direction of some literature relating to single phase loading of a three-phase Star Delta (YNd11) transformer.
My understanding is that when the primary neutral is connected, a sole single phase load connected between two phases...
