Let me start this post by saying that I'm a protection and controls engineer with a good bit of automation experience and while I have a decent amount of industry experience with controls, I have little to no experience with intrinsic safety. As such, I am humbly asking for some clarification...
When we model short circuit capacity of a synchronous generator, we usually model it based on the subtransient reactance for the "worst-case" scenario, which would also include the increase related to the DC offset based on the X/R ratio. For our purposes, let's just talk about the symmetrical...
I've recently moved jobs and am trying to come up to speed on SCADA and metering. Through an unfortunate series of events, it has happened that we are in a situation where we need to sum two meter accumulators (read via DNP/Serial) in our D20 RTU, once we've polled them. Unfortunately, I...
We have a an installation where we have two antennas installed on the roof of a metal frame building. One antenna is a GPS antenna that barely protrudes above the roof line. The other is an electrostatic antenna that protrudes about 6 or 7 feet above the edge of the roof from the side of the...
Does anyone know of a facility that will repair a General Electric CT-61A power line carrier transmitter? Normally, we'd just upgrade the unit to something newer but we are in a bit of engineering/design time crunch and would like to get the unit repaired if possible to avoid having to modify...
I’m embarrassed to ask this, but can anyone tell me if there is a definitive guide to what is meant by “minimum available fault current” on transmission systems? Traditionally, when I’ve been asked for this and I do not get more information from the requesting party, I give the fault...
We are currently trying to trouble-shoot a differential circuit on a delta-delta power transformer and are experiencing a strange phenomenon. We are consistently seeing a 10° to 15° phase shift between the HV and the LV windings of the transformer (measuring from the HV and LV CT's). To the...
We recently had an outside consultant suggest that we add surge arresters to the H0/X0 (neutral) bushings of our autotransformers. In every case, the neutrals are solidly grounded.
For the case where we have three single-phase transformers connected in a three-phase bank, with the individual...
Does anyone happen to know what year GE changed from rating their HV (138 kV) circuit breakers using the "Total Current" method vs the "Symmetrical Current" method? I believe the standards changed in 1964, but I don't think all manufacturers changed their rating methods that year. I am unable...
I'm trying to get a feel for the standard practices of other utilities with respect to how spare transformers are stored on-site (ready to be placed in service), with minimal risk to the transformer.
In our case, we have a single-phase auto that is a spare member of a three-phase bank. My...
I would like to get some opinions on the following scenario:
We have small generation unit that has a GSU (Generator Step-Up transformer) that is delta-connected on the 34.5 kV generator side and grounded-wye-connected on the 138 kV transmission side. The generator is a connected in a...
I'm currently trying to determine what the switching surge level would be at a particular substation on a 500kV system. Can anyone tell me what parameters determine this value?
I believe it is probably related to line length, inductance and capacitance, capacitor banks and other system...
Does anyone have a sample insulation coordination study I could see? I really don't want any proprietary information. I'm really looking for a guide or sample document to go off of. I just want to formally document my decisions and would like a good example of a typical format for such a...
I think it's a common rule that you usually want to install a surge arrester as close as possible to the terminals of the equipment you're trying to protect. One of the primary reasons is that increased lead length between the transformer terminals and the arrester terminals increases voltage...
